Drought stress
Masoumeh Pouresmael; Homayoun Kanouni; Fatemeh Seifi; Alaeedin Kordenaeej; Behzad Sorkhi; Ali Sajjad Bokaei
Abstract
IntroductionChickpea is mainly grown in the west and north west of Iran in dryland conditions, and in most areas, it is planted as post rainy season crop from March to late May. Due to irregular, untimely and insufficient rainfall in cultivated areas, this plant is usually suffering from drought during ...
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IntroductionChickpea is mainly grown in the west and north west of Iran in dryland conditions, and in most areas, it is planted as post rainy season crop from March to late May. Due to irregular, untimely and insufficient rainfall in cultivated areas, this plant is usually suffering from drought during flowering and pod filling stages, which are the most susceptible stages of chickpea growth. Utilization of local genetic diversity that are useful sources of adaptation gene to environmental changes is a starting point and a functional approach to overcome this problem. Assuming the local chickpea accession conserved in National Plant Gene Bank of Iran (NPGBI) have appropriate diversity for terminal drought tolerance, a research was conducted with the aim of identify drought tolerant accessions and determining their yield potential under dryland condition. Materials and methods Seventy Kabuli chickpea landraces were identified as tolerant accessions in different previous projects were done in NPGBI entered to this study. The experiment was held in Sanandaj and Karaj research station both in two different treatments. Control and drought treatments, through cutting off irrigation at flowering stage till maturity, in Karaj and dryland and complementary irrigation treatments, using two additional irrigations during flowering and pod filling, in Sanandaj station. The accessions were planted in the second half of March in augmented design, during 2016-17 growing season. Different agronomical traits were recorded, quantitative drought tolerance and susceptibility indices, were calculated and based of them accessions were grouped using the principle component and cluster analysis.Results and discussion Based on the results, a significant decrease in day to maturity, flowering period, canopy height and width, plant weight, pods number and weight per plant, seeds number per plant, plant yield, biomass, yield and harvest index were observed in drought stress conditions. There was considerable variation in yield and yield components, biomass and harvest index, among understudied landraces. Seed production increased by 9.7 and 1.3 times under irrigation treatment in Karaj and Sanandaj, respectively.Principal component analysis across tolerant and susceptible indices and considering eigen values greater than or equal to 1.0 showed that in both locations, two components together accounted for 92.32 and 99.33 percent of variation. The first component contributed most of the variability 52.18% in Karaj and 83.62% in Sanandaj was explained by variation in HM, STI, GMP and MP indices. The second component was explained by the diversity among genotypes for TOL and SSI indices. Hence, accession number KC.215172, KC.215286, KC215369 and KC.216010 in Sanandaj station and accession number KC.215286, KC.215727, KC215442, KC.215443, and KC.216023 in Karaj with higher amount of GMP and STI indices and lower amount of TOL and SSI were among more drought tolerance accessions.Cluster analysis based on evaluated traits and calculated drought tolerance and susceptibility indices, were divided accessions in to 3 clusters in Karaj. The cluster number three that TOl and SSI indices and the percentage of unfilled pods had lower values than the total average and plant weight, seed and pod number per plant, seed and pod weight per plant, biomass, yield, harvest index and STI and GMP indices have higher values than the average was called drought tolerant cluster. Accessions number KC.215727, KC.215442, KC.215710, KC.216023 were this cluster member. The cluster number 4 that had high yield potential and high STI and GMP indices and including 24 accessions was drought tolerant cluster in Sanandaj. Accession number KC215369 was in this group.ConclusionsAlthough it is possible to increase the yield of chickpea by changing the planting season from traditional spring planting to winter, but farmers still prefer spring planting. Therefore, it is necessary to produce suitable high-yielding cultivars for both seasons, because in this way, farmers have the opportunity to choose suitable cultivars for spring or winter planting, depending on their local environmental or climatic conditions. The mismatch between grouping of tolerant genetic accessions in two experimental locations was due to the lack of similarity of stress intensities between two locations. The intensity of stress was 0.89 in Karaj and 0.24 in Sanandaj and this issue affects the reaction of the accessions. Genotype × environment interaction is the most important challenge in breeding program. Therefore, description of interaction effects and finding out appropriate genotypes with specific or common adaptation for target environments is the most important aim for multi-year and multi-location assessments. Summarizing the results of both sites demonstrated accessions number KC.215286, KC.215442 and KC.215443 were superior genotypes at both locations.Totally, this study revealed the existence of desirable diversity in terms of agronomic traits and stress tolerance among local accessions of chickpea and highlighted the importance of paying attention to these accessions for advanced and complementary research to identify potentials of these valuable heritage.
Breeding plants for stress conditions
Roghayeh Fatemi; Mehrdad Yarnia; Soleman Mohammadi; Ebrahim Khalil Vand; Bahram Mirashkari
Abstract
IntroductionBarley (Hordeum vulgare L.) is a widely cultivated cereal crop in many rainfed areas in the Mediterranean region where drought is considered the main yield-limiting factor. In such marginal lands, yield losses are associated with drought conditions resulting from low and inconsistent precipitation ...
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IntroductionBarley (Hordeum vulgare L.) is a widely cultivated cereal crop in many rainfed areas in the Mediterranean region where drought is considered the main yield-limiting factor. In such marginal lands, yield losses are associated with drought conditions resulting from low and inconsistent precipitation during the whole plant growth cycle, either early in the fall or winter (initial drought conditions) or late during spring (terminal drought). Drought stress reduces grain yield of barley by negatively affecting the yield components i.e., number of plants per unit area, number of spikes and grains per plant or unit area and single grain weight, which are determined at different stages of plant development. Materials and methodsIn order to investigate the effect of sources limitation on yield and physiological characteristics in barley cultivars and advanced lines in various environmental conditions, an experiment was done in the Agricultural and Natural Resources Research Station of Miandoab in cropping 2016-2017. In this study, 12 varieties and lines of barley were evaluated in five sources limitation treatments including control (without limitation), leaf removal under flag leaf, flag leaf removal, half spike removal and spike coating in normal irrigation and water deficit conditions were evaluated in a randomized complete block design with three replications. In this study spike weight, leaf weight, peduncle weight, internode weight, seed number per spike, total plant weight and single plant yield were measured. Analysis of variance was performed using the SAS9.4 and SPSS programs. Result and discussionThe results of the combined analysis of variance showed that the effect of year on leaf weight and seed yield was significant at the level of 0.01. There was a significant difference between irrigation levels on all studied traits at the level of 0.01, the interaction effect of year in irrigation was also significant on all traits except total plant weight at the level of 0.01 probability. The effect of resource constraint, irrigation on resource constraint, genotype and the interaction of genotype on resource constraint were significant on all studied traits at the level of 0.01 probability. The interaction effect of year on resource constraint on leaf weight, peduncle weight, number of seeds per spike and seed weight was significant at 0.01 probability level. The interaction effect of year on genotype on total plant weight and number of seeds per spike was also significant. The interaction effect of irrigation in genotype was also significant on all traits at 0.01 probability level. Finally, the triple interaction of irrigation in source restriction in genotype on leaf weight and total plant weight was significant at the level of 0.01 and the number of seeds per spike and grain yield at the level of 0.05 probability was significant. Comparison of the mean of genotype with source restriction interaction treatments showed that most of the studied genotypes under normal irrigation conditions showed the lowest grain yield in treatments of flag leaf removal restriction, half spike target and spike cover, while under water deficit stress conditions, the lowest grain yield was recorded in the studied genotypes under the treatments of flag leaf removal and spike cover. Under normal irrigation conditions under control and removal under the flag leaf, genotypes No. 10, 2, 3, 4, 5, 6, 7, 8 and 12 had the highest grain yield and there was no significant difference between them. Under water deficit stress conditions, in the control treatment, all genotypes except genotype No. 11 and in flag removal treatment, all genotypes, except for genotypes No. 2 and 11, had higher yields compared to genotypes. Under normal irrigation conditions and Water-deficit stress in genotype 3, there was no significant difference between control treatment and resource limitation treatments of remove below the flag leaf, flag leaf removal and half spike removal. In this study, the studied advanced lines did not show a significant advantage over the released barley cultivars in terms of grain yield. ConclutionIt can be concluded that in this study, the studied advanced lines did not show a significant advantage over the released barley cultivars in terms of grain yield.
Drought stress
Parisa Sheikhzadeh; Mohammad Amani; Saeid Khomari; Nasser Zare; Nasrin Razmi
Abstract
IntroductionSoybean is one of the most important products in Iran, due to the production of high-quality oil and protein-rich meal. Soybean is highly sensitive to water deficit stress at the flowering and grain filling stages, so the end-season drought stress can have negative effects on soybean yield ...
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IntroductionSoybean is one of the most important products in Iran, due to the production of high-quality oil and protein-rich meal. Soybean is highly sensitive to water deficit stress at the flowering and grain filling stages, so the end-season drought stress can have negative effects on soybean yield and yield components. Therefore, increasing soybean tolerance to drought stress is very important. Due to the importance of the soybean plant and the existence of drought stress in Iran, Improving the agronomic characteristics and yield of this crop under drought stress as well as favorable conditions through agronomic treatments is essential. Considering the positive effects of nutrients availability on the plant's physiological traits and yield, this study aimed to investigate the effect of foliar application of nutrient elements and polyamine on agronomic and physiological characteristics of soybeans under the end-season drought stress. Materials and methodTo investigate the effect of fertilizer on physiological and yield characteristics of soybean (Glycine max) under the end-season drought stress, a split-plot experiment was conducted in a randomized complete block design (RCBD) with three replications at the Agricultural and Natural Resource Research Center of Ardabil in 2019. The treatments were irrigation (normal irrigation and omitting irrigation at the flowering stage) as main plots and foliar applications (control, nutrient elements containing polyamine, nutrient elements without polyamine) as sub-plots. Foliar application of nutrient elements without polyamine and nutrient fertilizer containing polyamine were applied one month after planting (at the vegetative stage). Drought stress was applied through irrigation stopping at the flowering stage (50% flowering). One week after drought stress, chlorophyll index, relative water content (RWC), and electrical conductivity (EC) were measured. Furthermore, the plant height, number of branches, pod per plant, grain per pod, 100-grain weight, biological and grain yield per unit area, harvest index, and oil percentages and oil yields were measured at the physiological maturity stage. Results and discussion The results showed that drought stress decreased the chlorophyll index, leaf relative water content (RWC), and grain and oil yield of soybean seeds, and significantly increased the electrolyte leakage. Furthermore, plant height, the number of branches, pods per plant, grain per pod, biological yield, and 100-grain weight were significantly decreased under drought stress treatment compared to the normal condition. Under drought stress, foliar application of nutrient elements without polyamine caused an increase of about 43.05 percent in the number of branches, 45.11 percent in the number of pods per plant, 38.84 percent in biological yield, and 40.09 percent in grain yield, as compared to the control. Under normal irrigation conditions, foliar application of nutrient elements containing polyamine significantly increased the number of branches (23.6 percent), the number of pods per plant (11.45 percent), grain yield (24.88 percent), and biological yield (20.20 percent), as compared to the control. It seems that nutrient elements without polyamine improved the soybean yield and yield components through the provision of suitable nutritional conditions during the seed formation and filling period. Furthermore, under normal irrigation conditions, the application of polyamine with the nutrient fertilizer improved the growth characteristics and yield of soybeans compared to the nutrient fertilizer without polyamine, which indicates the synergistic effects of polyamine and nutrient element. ConclusionsThe results showed that drought stress during the flowering stage significantly reduced the chlorophyll index and relative water content (RWC) of the leaves and increased electrolyte leakage in soybean plants and finally reduced yield and yield components of soybean. Under drought stress, foliar application of nutrient elements without polyamine significantly increased the chlorophyll index, RWC, and reduced EC of the soybean leaves, which resulted in the improved agronomic and physiological characteristics and yield of soybean plants under end-season drought stress conditions. Therefore, foliar application of nutrient elements with or without polyamine under favorable and unfavorable environmental conditions had a positive and significant effect on the physiological traits and yield of soybean, through providing better nutritional conditions for soybean plants.
Drought stress
Esmaeil Afshoon; Hossein Moghadam,; Mohammad Reza Jahansooz,; Mostafa Oveisi,; Ehsan Rabieian
Abstract
IntroductionThe first factor limiting plant yield in many crop ecosystems is drought stress, and plant productivity under these conditions depends on the distribution of dry matter between plant organs and the spatial distribution of roots in the soil. Knowledge of root length conditions and its distribution ...
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IntroductionThe first factor limiting plant yield in many crop ecosystems is drought stress, and plant productivity under these conditions depends on the distribution of dry matter between plant organs and the spatial distribution of roots in the soil. Knowledge of root length conditions and its distribution in soil profile, which is an indicator of the ability of plants to absorb water from deeper layers and better root permeability in the soil, as well as understanding the shape of the root system, is important (Wasson et al., 2012). In general, the size, morphology, and architecture of the root system determine the plant's ability to absorb water and nutrients, as well as the relative size and growth rate of the shoot (Vamerali et al., 2003). Root growth is determined by the genetic characteristics of the plant as well as the physical and chemical characteristics of the soil. Even in wet areas in response to drought stress, root growth is limited to the topsoil, and when the soil dries, its infiltration resistance increases rapidly, resulting in a combination of drought stresses. Soil and its infiltration resistance (He et al., 2017). Reduction of root dry weight in rice (Nasiri et al., 2015), fresh weight of root in rapeseed (Razaviezadeh and Amoubeigi, 2013) indicate the negative effect of drought stress on root characteristics in Different plants. Tillage is the only crop method by which humans can directly affect soil properties. Moisture storage and aeration to the roots, depending on the desired or unfavorable application of tillage, affects the growth and development of plant roots and ultimately its yield (Bronick and Lal, 2005).Material and methodsThis experiment was conducted in split -split plots based on randomized complete block design with three replications. Tillage systems as the main -plot in two factors was including no tillage and conventional tillage, Water stress as the subplot in three levels by 30, 60 and 90 Percent of moisture requirement and nitrogen urea as the sub-sub plot at three levels by 0, 50 and 100 percent of the recommended rate.ResultsThe combined variance analyses indicated that the maximum root length (4147 cm per plant), root volume (158.13 cm3 per plant), root area (3055.7 cm2 per plant), root length density (0.44 cm2. cm-3), root dry weight (24.32 gr pl-1) and plant fresh weight (6732.6 gr. m-2) was obtained from the interaction of conventional tillage in mild drought stress (90% of the plant's water requirement) in 100% of the plant's nitrogen fertilizer requirement. Also, the interaction effect of severe drought stress (30% of plant water requirement) in 100% of plant nitrogen fertilizer requirement led to a sharp decrease in studied traits in both studied tillage systems. Although the conventional tillage system in this study ultimately increased the root growth characteristics and fresh weight of the forage maize plant, but because no significant difference in wet forage yield was observed in both studied tillage systems, the system no tillage is recommended because it can improve the physical and chemical properties of the soil in the long turn.
Physiology of crops under stress conditions
Mirreza Miri; Farshad Ghooshchi; Hamidreza Tohidi Moghaddam; Hamid Reza Larijani; Pourang Kasraie
Abstract
IntroductionDrought is one of the most important factors limiting growth and production in crops and therefore use of management methods to reduce the effects of drought is very important. Water deficit stress is one of the most important factors limiting the growth and survival of plants in arid and ...
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IntroductionDrought is one of the most important factors limiting growth and production in crops and therefore use of management methods to reduce the effects of drought is very important. Water deficit stress is one of the most important factors limiting the growth and survival of plants in arid and semi-arid regions of the world. Water is a major component of the fresh produce and significantly effects on weight and quality of plants. Also, water deficit may cause significant changes in the component yield and yield in plants. Iran with an average annual rainfall of 240 mm is included among arid and semi-arid regions of the world. Of the million hectares of cultivated region, only five millions are under irrigation because of intense water limitations. However, Iran is one of the world’s cowpea producers. Cowpea has been cultivated for many years in different parts of Iran. Therefore, high production and development of cowpea is important in coriander. This research was conducted to evaluate the effects of foliar application of glycine betaine (GB) and gibberellic acid (GA) on physiological characteristics, yield and yield components under drought stress conditions in cowpea.Materials and methodsTo evaluate the effects of foliar application of glycine betaine (GB) and gibberellic acid (GA) on physiological characteristics, yield and yield components under drought stress conditions, a factorial split plot experiment based on randomized complete block design with three replications was conducted during the 2018 crop year. Experimental factors included irrigation regimes (50, 70 and 90 mm evaporation from Class A evaporation pan) in main plots and glycine betaine (no foliar application, 50 and 100 mM) and gibberellic acid (no foliar application, 60 and 120 ppm) were in factorial form in sub plots. Data were collected on relative water content, ion leakage, chlorophyll a, chlorophyll b, total chlorophyll, carotenoids, pod number per plant, seed number per pod, hundred seed weight, seed yield and biological yield.Results and discussionThe results of ANOVA indicated that the effects of irrigation regime, glycine betaine and gibberellic acid were significant for relative water content, ion leakage, chlorophyll a, chlorophyll b, total chlorophyll, carotenoids, pod number per plant, seed number per pod, hundred seed weight, seed yield and biological yield. The results of comparison of means showed that by increasing drought stress the traits of relative water content, chlorophyll a, chlorophyll b, total chlorophyll, carotenoids, pod number per plant, seed number per pod, hundred seed weight, seed yield and biological yield decreased but the ion leakage significantly increased. Nonetheless, exogenous application of glycine betaine and gibberellic acid increased relative water content, chlorophyll a, chlorophyll b, total chlorophyll, carotenoids, pod number per plant, seed number per pod, hundred seed weight, seed yield and biological yield but the ion leakage significantly decreased. It seems that glycine betaine and gibberellic acid improved the growth indices of cowpea by reducing the adverse effects of drought stress. Therefore, exogenous application of glycine betaine and gibberellic acid can be used as a useful method for improving drought tolerance in cowpea.ConclusionGenerally, the results indicated that glycine betaine and gibberellic acid improved the growth indices of cowpea by reducing the adverse effects of drought stress. Therefore, exogenous application of glycine betaine and gibberellic acid can be used as a useful method for improving drought tolerance in cowpea. Also, the results showed that concentrations of 100 mM glycine betaine and 120 ppm gibberellic acid were more effective than other levels and induces more water stress tolerance in cowpeaAcknowledgementsThe authors thank from the Gene bank of the Seed and Plant Improvement Institute of Karaj, Iran for making available plant materials.
Drought stress
Sahar Fallah; Khosro Azizi; Hamid Reza Eisvand; Omidali Akbarpour; Naser Akbari
Abstract
IntroductionClimate change (temperature, rainfall and flood patterns, etc.) has major and negative effects on agricultural production and water and land resources. Part of climate change is to reduce soil fertility (through erosion processes), increase the frequency of repeated pest attacks, reduce crop ...
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IntroductionClimate change (temperature, rainfall and flood patterns, etc.) has major and negative effects on agricultural production and water and land resources. Part of climate change is to reduce soil fertility (through erosion processes), increase the frequency of repeated pest attacks, reduce crop yields, and increase groundwater harvest periods by reducing water access. Zinc plays an essential role in the basic processes of plant life, namely cell division, stomata regulation and respiration. Apart from the increase in carbon dioxide emissions, high temperatures are also a major stressor that can lead to severe growth retardation and plant distribution. At higher concentrations, carbon dioxide increased photosynthetic carbon and increased organic matter, which in turn increased stem diameter of lentil plant (Shams, 2017) .Materials and methodsThe composite experiment was performed as a factorial experiment in a completely randomized design with four replications. Irrigation at three levels (60, 80 and 100% of field capacity) as the first factor, foliar application of zinc sulfate fertilizer at two levels (no foliar application and 0.5 gl-1) as the second factor and environmental conditions at four levels (380_24, 380_31, 700_24 and 700_31 C/PPm (carbon dioxide) were the third factor. The studied traits were number of root nodes, root dry weight, stem height and diameter, number of leaves and grain yield. Data were analyzed using SAS 9.1 software and the mean of the treatments was compared with LSD test at 5% probability level.Results and DiscussionCo-application of carbon dioxide, complete irrigation and complete irrigation and zinc sulfate increased the number of nodes. Increasing the concentration of carbon dioxide under severe drought stress increased root dry weight. Also, increasing the concentration of carbon dioxide under mild environmental stress caused plant height, diameter and grain yield. Increasing the concentration of carbon dioxide in full irrigation conditions increased the number of leaves. Increasing carbon dioxide increases water use, photosynthesis and net primary productivity by reducing stomatal conductance and transpiration, which ultimately increases biomass and yield.Application of zinc sulfate under full irrigation conditions increased the total grain yield by 17.1 g/plant. Positive role of zinc in chlorophyll synthesis, and performance of optical photosystems can increase growth indices. The use of zinc chelate due to the role of zinc in the activity of plant enzymes and metabolisms, including plant hormones (auxin) has increased chlorophyll activity and photosynthesis, which finally has increased grain yield in the plant. ConclusionIncreasing the concentration of carbon dioxide at lower temperatures and full irrigation and mild stress increased the majority of morphological traits. Also, application of zinc alone and with full irrigation increased some morphological traits and grain yield.
Drought stress
Seyed Amir Reza Tahaei; Mohammad Nasri; Ali Soleimani; Farshad Ghooshchi; Meisam Oveysi
Abstract
IntroductionCorn (Zea mays L) is an annual cereal crop adapted to various ecological conditions. Corn with wheat and rice are three strategic agricultural products in the world. Drought stress is the crucial factor to limit the production of corn among abiotic stresses. Drought stress in corn reduces ...
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IntroductionCorn (Zea mays L) is an annual cereal crop adapted to various ecological conditions. Corn with wheat and rice are three strategic agricultural products in the world. Drought stress is the crucial factor to limit the production of corn among abiotic stresses. Drought stress in corn reduces photosynthesis, and consequently grain yield by reducing the leaf chlorophyll level. Many external and internal factors are effective in plant growth. The most important internal factors are hormones and the most important external factors are light and temperature. Hormones regulate Plant Growth Regulators (PGRs) and coordinate the processes occurring in different parts of the plant body. Plant Growth Regulators (PGRs) increase plant tolerance to various environmental stresses, such as drought, salinity, cold, and heat, and this increase in tolerance to environmental stresses depends on the production of transcripts of anti-stress genes, such as heat shock genes and LEA genes. It is possible to divide the products of genes induced under drought stress conditions into two categories: (1) Those playing a direct protective role against stresses; (2) Those controlling gene expression and message transmission. The Rab-17 gene is one of the genes whose expression increases during drought stress following an increase in ABA. This gene belongs to second group LEA proteins. Several gene products identical to Rab17-encoded proteins have been identified in different plants. Studies indicate that LEA proteins act as water-binding molecules in grains and protect other proteins against the negative effects of drought, including ion separation from macro molecules and membrane protection against freezing damage. This study was conducted to examine the effect of the foliar application of proline amino acid and growth regulators, including benzyl adenine, gibberellic acid, as well as the combination of benzyl adenine and gibberellic acid and proline amino acid on the growth, yield and expression of the Rab-17 gene in corn (Zea mays L) (Single Cross 704) under drought stress.Material and methodsThis study was conducted as a split plot on the base of randomized complete block design with three replications in 2015 and 2016. Three irrigation treatments were considered, including after 70 (control), 90, and 100 mm evaporation from the surface of standard Class A evaporation pan as the main agent. Phytohormones BA6, GA (3+ 7), proline amino acid, BA6+ GA (3+ 7) +AA and pure water as control were considered five levels of the sub-factor. The plants were irrigated every 10 days before water stress was applied. Mild and severe stress treatments were applied 45 days after planting and in the 12-leaf stage. Afterward, foliar Plant Growth Regulators (PGRs) and proline were applied in the stem elongation stage of corn.Results and discussionThe results and analysis of the data indicate that all the measured traits decreased with drought stress; however, the proline content increased by increasing the drought stress. For example, drought stress reduced forage yield by 46%. Corn yield was 1.3 times of the control treatment under severe drought stress with foliar application of proline amino acid. In the genetic experiments, increase of drought stress did not increase the PCR response to the Rab-17 gene due to the increased secretion of abscisic acid (ABA) and susceptibility of single cross 704 to drought stress.ConclusionsAccording to the results, the foliar application of proline amino acid and Plant Growth Regulators (PGRs) can improve the growth and yield of corn under drought stress by improving plant physiological and genetic responses. Furthermore, the change in the expression of a number of genes appears to be occurred in response to drought stress. The results indicate that gene expression plays a vital role in the drought tolerance of corn; hence, it is suggested to be highly examined in further studies. It is possible that the current results draw our attention to the effects of tested Plant Growth Regulators (PGRs) on the physiology and genetic contents of corn in drought conditions to use the regulators at the right time to deal with environmental stresses in addition to perform proper management in the field, and to increase the efficiency of roots to uptake nutrients.AcknowledgmentsThe authors thank Islamic Azad University, Varamin and the Khorasgan branches, as well as Isfahan University of Technology for providing the university with necessary facilities and performing protein and genetic tests.
Drought stress
Roghaye Bamshad; Ali Reza Sirousmehr; Aliakbar Mahmoodi; Noralla Heydarisadegh
Abstract
IntroductionDrought stress not only is one of the most unfavorable factors for plant growth and its productivity but also a serious menace to sustainable crop production and food security under conditions of climate change. In order to, optimum water consumption in agricultural production, appropriate ...
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IntroductionDrought stress not only is one of the most unfavorable factors for plant growth and its productivity but also a serious menace to sustainable crop production and food security under conditions of climate change. In order to, optimum water consumption in agricultural production, appropriate methods should be considered such as changing the planting pattern, cultivation of drought-tolerant plants and some species of medicinal plants. Portulaca oleracea from family Portulacaceae. is a four-carbon compound and annual plant. Portulaca oleracea has antioxidants and high amount of Omega-3 acids which could strengthens the immune system and deactivate free radicals. Therefore, prevents cardiovascular disease, cancer, asthma, diabetes type 1 and infectious diseases. The main objective of this study is to investigate of drought stress and humic acid spraying effects on some physiological characteristics of Purslane. Materials and methodsA split plot experiment was conducted in a randomized complete block design with three replicate in the research farm of Zabol University (Sistan Dam) during 2016-2017. Drought stress was performed on three levels: (90, 70 and 50) % FC and humic acidic in four levels (0, 25, 50 and 75 mg L-1). During and the end of experiment some traits were measured such as height, number of lateral branches per plant, fresh and dry root weight, leaf chlorophyll index, photosynthetic pigments, carbohydrates and proline. measuring the proline content and Carbon hydrate content of leaves have been done by using the Bates (1973) and Schlegel (1956). methods, respectively. (Analysis of variance was performed by using SAS statistical software version 9.1. Comparison of means was performed by using Duncan's multiple range test at the 5% significance level.ResultsThe results showed that the combination of drought stress and humic acid spraying had a significant effect on all studied traits. Maximum plant height was achieved at 70% drought stress and 75 mg L-1 of humic acid, the highest root length was 50% and 50 mg L-1 of humic acid, the highest fresh and dry weight of root were obtained from 90% and 75 mg L-1 of humic acid. The highest amount of carbohydrates and proline were obtained at 50%FC and 50 mg L-1 humic acid. The maximum photosynthetic pigments was observed under combination of 50 %FC and 50 mg L-1 of humic acid.ConclusionAccording to the results of this research, despite of increasing proline and carbohydrates under stress conditions, the highest values of traits were obtained under medium stress 70% FC. Therefore, according to water shortage in the study area, medium stress (70% FC) for Production of Portulaca oleracea can be proposed. The use of humic acid in the cultivation of medicinal plants can reduce the harmful effects of chemical fertilizers and increase the quantity and quality of plant production. In addition, could play an important role in sustainable agriculture.
Drought stress
Masumeh Alizadeh Forutan; Soheil Parsa; Majid Jami Al-Ahmadi; Sohrab Mahmoodi
Abstract
IntroductionMaize is the third most important agricultural crop in the world in terms of production, That production and demand has increased by 45% in 2020 compared to 1997. Abiotic stresses in many cultivated areas of this plant have a negative impact on its production and these effects are expected ...
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IntroductionMaize is the third most important agricultural crop in the world in terms of production, That production and demand has increased by 45% in 2020 compared to 1997. Abiotic stresses in many cultivated areas of this plant have a negative impact on its production and these effects are expected to intensify in the near future.Inefficient use of water in agricultural production in arid and semi-arid regions is one of the most important factors in exacerbating the water crisis and water shortage is a serious limiting factor in agricultural production. The use of technologies to improve water use efficiency in crops is very important for sustainable crop production and food security. Deficit irrigation is a water-saving strategy that is commonly used in arid and semi-arid regions and leads to increased water efficiency. According to studies, Deficit irrigation can save irrigation water, maintain or increase crop production and improve its quality. One of the methods for optimizing water consumption in agriculture is the addition of moisture absorbent such as Zeolite, which by gradually providing absorbed water and nutrients to the soil, play an important role in fertility and preventing water loss. The use of zeolite, especially in sandy soils that exposed to drought stress, can improve growth and final yield by absorbing and controlling moisture release and increasing soil moisture capacity. Because of low rainfall and also limitation of water resources in Birjand region, efficient use of water in agriculture, especially in the production of important cereals such as Miaze, is very important. The aim of this study was to investigate the application of zeolite and deficit irrigation methods for optimal use of water and achieving optimum yield in Maize in this region. Materials and methodsIn order to investigate the effect of irrigation and Zeolite on maize, a field experiment was conducted on two planting dates in 2017, factorial based on a randomized complete block design with three replications. The factors including Zeolite in two levels and deficit irrigation in eight levels include: 100% water requirement, 75% water requirement in vegetative stage with: conventional irrigation, Fixed alternate partial root-zone irrigation, nonfixed alternate partial root-zone irrigation, and 75% water requirement in total growth with Fixed alternate partial root-zone irrigation, 50% water requirement in vegetative stage with: conventional irrigation, Fixed alternate partial root-zone irrigation, nonfixed alternate partial root-zone irrigation. Results and discussionTraits measured on the second date of planting had the highest value compared to the first date. Deficit Irrigation reduced the total dry weight and grain yield, but the use of zeolite improved these indicators. Total dry weight, number of grains per ear, grain yield, harvest index and water use efficiency had the highest value in irrigation control treatment and decreased with deficit irrigation, so that the lowest value in conventional irrigation treatment The basis of 50% of water requirement in the growing season was observed with 23, 26, 38, 27 and 19% reduction, respectively. Zeolite application had a favorable effect on all traits, but the effectiveness of some traits was different during planting dates, so that the rate of yield increase on the second planting date (37%) was higher than the first date (27%). The highest water use efficiency was obtained on the second planting date and Fixed alternate partial root-zone irrigation based on 75% of water requirements during the growing season and total growth with 0.7 and 7.6 due to the increase in observation, had the highest Were the amount. Although the yield decreased in deficit irrigation treatments, but due to the increase in harvest index and water use efficiency, excess water due to under-irrigation can be spent on irrigating more lands and increasing production. ConclusionOne of the important goals of production in areas with water constraints is to increase the yield per unit of water. According to the results, after the control treatment, the highest harvest index was related to 75% water requirement in vegetative stage with Fixed alternate partial root-zone irrigation treatment. Also, based on water use efficiency, to 75% water requirement in vegetative stage with Fixed alternate partial root-zone irrigation and 75% water requirement in total growth with Fixed alternate partial root-zone irrigation treatments were better than other treatments with a superiority of 0.69 and 7.59% compared to the control treatment. Despite saving 19.84% of water consumption in low irrigation treatments, 50% of water requirement in the growing period, but did not get an acceptable result from this treatment (33.74% reduction in yield and 13.79% efficiency). Water consumption). It seems that the relatively severe lack of water during vegetative growth has caused serious damage to the roots of the plant, which in the later stages of growth, despite the optimal irrigation of the plant could not use the water in the root environment well. Regardless of the reduction in yield and considering the water use efficiency that was obtained in 75 water requirements treatments in the form of atmospheres and constant intermediate stacks in the vegetative period and the whole growth period, it seems that these two treatments for Execution in Birjand region should be more appropriate.
Drought stress
Elham Elahifard; Abolfazl Derakhshan
Abstract
IntroductionSeed germination is largely regulated by two factors, temperature (T) and the amount of seedbed water potential (ψ). Hence, hydrothermal time models have been widely used to describe seed germination patterns in response to these two environmental factors. In this study, a new hydrothermal ...
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IntroductionSeed germination is largely regulated by two factors, temperature (T) and the amount of seedbed water potential (ψ). Hence, hydrothermal time models have been widely used to describe seed germination patterns in response to these two environmental factors. In this study, a new hydrothermal time model based on the Gumble distribution is presented that 1) by considering the thermoinhibition of germination at high temperatures, it simply explains the germination dynamics of seeds in response to drought stress in both sub- and supra-optimal range; 2) includes mathematical solutions for estimating critical T thresholds; and 3) explains well any systematic change in critical T thresholds due to water availability for different germination fractions (g). The developed model was fitted to the germination data of volunteer rapeseed in response to two factors T and ψ, based on which the effect of moisture stress on the values of critical germination T thresholds of this plant was modeled.Materials and methodsThe experiment was conducted at the Seed Technology Laboratory of Agricultural Sciences and Natural Resources University of Khuzestan in 2020. Germination test was performed at temperatures of 10, 15, 20, 25, 30, and 35 °C. In each of these T regimes, the germination response of seeds to different levels of drought stress, i.e., osmotic solutions with concentrations of 0, -0.3, -0.6, and -0.9 MPa was evaluated. The germination test was performed with four replications (each Petri as one replicate). In each replicate, 40 seeds were placed on a layer of Whatman No 1 filter paper in an 8-cm glass Petri, and then moistened with 5 ml distilled water or other osmotic solutions. The number of germinated seeds was counted twice daily until the end of the test or cessation of germination in each T regime. The following model was fitted to the cumulative germination data of volunteer rapeseed to explain the germination behavior of this species in response to different levels of ψ and T. (1)The optimum (To) and maximum (Tm) temperatures for germination were also determined using the following equations: (2) (3)Fitting of models to germination data was performed using SAS (version 9.4) and PROC NLMIXED procedure in this program.Results and discussionAt each of the T regimes, the Gumble hydrotime model provided a good fit to the cumulative germination data of volunteer rapeseed in response to different water potentials. The two parameters θH (hydrotime constant) and μ (location) (and thus ψb(50) (median base water potential)) showed a defined trend with increasing T, but the coefficient σ (scale) was not affected. The value of ψb(50) linearly increased toward more positive values in response to an increase in T, whereas θH decreased curvilinearly with T. Whereas the increase in ψb(50) implies that seeds need more water availability to proceed germination at higher temperatures, the decline in θH indicates a promoting effect of increased temperatures on germination speed. The Gumbel hydrothermal time model was able to describe the germination pattern of volunteer rapeseed reasonably well, as there was a close match between observed and fitted values. The model estimated the coefficients θHT (hydrothermal time constant), Tb (base T), ψbase(50) (median base water potential at T=Tb) and KT (slope of changes in ψb(g) with T) as 305.50 MPa °C h, 5.17 °C, -1.375 MPa and 0.044 MPa °C-1, respectively. For this species, To and Tm were warmer for low percentiles, but they gradually became cooler with increasing g. Both these critical T thresholds also decreased proportionally with increasing drought stress intensity. The hydrothermal time model developed herein was able to reveal some adaptive characteristics in the germination response of volunteer rapeseed to T and ψ environments.ConclusionsBased on the results obtained here, ψb(g) showed an increasing trend in response to an increase in T in the range between Tb to Tm(g), and its changes were limited to temperatures beyond To. Both To and Tm become cooler for higher germination percentiles and more severe drought stress levels. This means that volunteer rapeseed seeds can germinate only in a narrower T range under drought stress, which itself is a conservative strategy.
Salinity stress
Hassan Monirifar; Arezoo Mirmozaffari
Abstract
IntroductionAlfalfa (Medicago sativa L.) is one of the most important forage crops and it produces high quality fodder for all types of livestock and alone can provide energy, protein, minerals and vitamins for livestock. Alfalfa is relatively sensitive to the salinity, but it has a high genetic diversity ...
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IntroductionAlfalfa (Medicago sativa L.) is one of the most important forage crops and it produces high quality fodder for all types of livestock and alone can provide energy, protein, minerals and vitamins for livestock. Alfalfa is relatively sensitive to the salinity, but it has a high genetic diversity that can be used to select resistant cultivars. Therefore, the success of selection of alfalfa resistant cultivars requires exploitation of this genetic diversity that can produce more resistant plants to salinity compared to other forage plants, thus cultivar selection is important for alfalfa hay production. The aim of this project was to evaluate the tolerance of new alfalfa cultivars to salinity in field conditions.Material and methodsThis research was carried out in 2017 and 2020 at the Research Farm of East-Azarbaijan Agricultural and Natural Resources Research and Education Center, Tabriz, Iran (Firuz Salar village located 4 km from Azarshahr city). In this study, two synthetic cultivars A and B along with a local ecotype as a control cultivar were compared in saline water and soil conditions. Synthetic A cultivar was selected from 11 ecotypes based on general combining ability test and evaluation of half-sib families, which eventually led to the production of Synthetic A cultivar. Synthetic cultivar B has been produced by selecting superior genotypes from five elite ecotypes. With polycross of selected genotypes in completely isolated conditions, synthetic cultivar B has been produced. Synthetic cultivars and common ecotype and local control were evaluated in a randomized complete block design with three replications. The field was irrigated with saline water of the experimental area. Chlorophyll index, plant height, stem diameter, leaf area index, fresh and dry forage yield in each harvest and their annual total, leaf to stem ratio, protein content, digestibility, ADF, NDF, and the chlorophyll content a and b were measured.Results and discusionsThe results showed that there was a significant difference between the studied cultivars for all measured traits at the level of 1% probability and also the effect of harvest was significant for all traits except leaf to shoot ratio. The mean height in both synthetic cultivars A and B was higher than the control cultivar and both were in a statistical group. Similar results were observed for fresh and dry forage yield, leaf area index, stem diameter, leaf to shoot ratio and chlorophyll index and synthetic cultivars were superior to the control cultivar.The average fresh forage yield of synthetic cultivars A and B in each harvest was 18.06 and 17.81 tons per hectare, respectively, which was significantly higher than the average fresh forage yield of the control cultivar (15.24 tons per hectare). For dry forage yield was quite similar and dry forage yield of synthetic cultivars was significantly higher than the control cultivar. Synthetic cultivars were superior to control cultivar in terms of chlorophyll content. It seems that improving the photosynthetic ability of these cultivars is one of the reasons for the high forage yield in these cultivars.ConclusionsThe results showed that there was a significant difference between the studied cultivars for all measured traits. The average fresh forage yield of synthetic cultivars A and B in each crop was 18.06 and 17.81 tons per hectare, respectively, which was significantly higher than the average fresh forage yield of the control cultivar (15.24 tons per hectare). For dry forage yield, quite similar results were obtained and the dry forage yield of synthetic cultivars was significantly higher than the control cultivar. The mean height in both synthetic cultivars A and B was higher than the control cultivar. On average, during the three years of the study, the third and second harvest produced the highest fresh forage yields. It seems the cultivars that have been modified for normal conditions also appear to be better under stress conditions. According to the total results obtained, synthetic cultivars have the necessary potential for cultivation under salinity conditions similar to the conditions of this study.
Salinity stress
Peyman Varjavand; Sayed Bahram Andarzian; Ali Mokhtaran; Abdolnour Mosadeghi
Abstract
IntroductionAccording to the growing human need for food production, using of unconventional water is defined as one of the strategies for overcoming the water crisis in the world. Drainage water recirculation for producing economic sustainable agricultural products can be very useful to management of ...
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IntroductionAccording to the growing human need for food production, using of unconventional water is defined as one of the strategies for overcoming the water crisis in the world. Drainage water recirculation for producing economic sustainable agricultural products can be very useful to management of drainage water environmental impact and adapt with water crisis in the world. For this purpose, overcoming on salinity stresses and preservation of soil quality during cultivation are so important. Studying on salinity effect of irrigation water on wheat yield and soil salts has a long history in the world but genotype and climatic conditions are very influential on the results, so do this research can be very useful. This research has been conducted to determination the best genotype of wheat and analysis of soil behavior in the study of solutes in it.Materials and methodsThis research was conducted in 2018-2019 in an experimental farm of AmirKabir Agro-Industry Sugarcane Company using split plot design with randomized complete block with three replications, yield reaction of 20 genotypes of wheat to irrigation with sugarcane drainage water farms was investigated. Also applied water volume, farm water requirement and drainage water effect on soil salts were analyzed. Main plots was irrigation water quality with two quality: 1- fresh water with EC=1.3 dS m-1 and 2- sugarcane drainage water with EC=7.0 dS m-1. Sub plots were 20 genotypes of bread and durum wheat which is cultivated in 8 lines and 20 cm distance. Water requirement was determined by 10-years climate data and wheat crop coefficient and calculated using FAO Penman-Monteith method. Field irrigation management was performed based on water requirement information and considering soil physics, leaching requirements and effective rainfall. Extracted information included volume of applied water, salt and moisture soil samples, water and drainage water quality samples, physical soil specifications, grain yield, biological yield, spike per square meter, grain per spike, 1000-grain weight and flowering date. Results and discussionResults showed that using sugarcane drainage water reduced the mean yield by 9.7% and decreased irrigation water productivity from 1.08 to 0.97 kg m-3. There is no significant difference between Bow, Shoele, Narin, Bloudan, Sarang, Irna, Spn and Pishtaz varities for using Karun River and drainage water in terms of grain yield, biological yield, spike per square meter, grain per spike, 1000-grain weight and flowering date, so it can be concluded that these genotypes are stable in different environmental conditions. Stress tolerance index varied from 0.57 to 1.22 among different genotypes. 1-63-31 and Narin genotypes had the highest and the lowest tolerance indices, respectively. Bam and Shoele genotypes were in the mean group with 0.92 and 0.89, respectively. Overall, Sistan, 1-63-31, Bow, Shoele, Sirvan, Sarang, Irna, Khalil, Barat, and Pishtaz with an index above the mean index (0.90) are among the most tolerant and it can be concluded that they can be considered as the most tolerant figures. Also Barat genotype had maximum applied water and total water productivity with fresh water irrigation which were 1.35 and 1.14 kg m-3 and Sistan had maximum water productivity for drainage water in these parameters which were 1.16 and 0.98 kg m-3. Soil results showed that using agricultural drainage water for irrigation not only led to changing farm soil from non-saline to saline condition, it closes to become sodic. Under drainage water cultivation conditions, soil quality will be compromised, which will require new development of irrigation management, leaching and cropping patterns. In these conditions, accurate knowledge of the time and amount of water required for wheat, irrigation with high efficiency and application of appropriate amount of leaching water with proper field drainage, can be effective.ConclusionsThis research was conducted to reaction investigation of various genotypes of wheat in condition of using sugarcane drainage water. Due to the fact that in the middle of autumn and late winter, the drainage of sugarcane fields is low and in this period, most of wheat water requirement is supplied by rainfall and the most important irrigation events start after winter in Khuzestan, so wheat had been chosen for this research. Results showed that yield decrease in drainage water farm for 20 studied genotypes was about 9.8% which is varies between 30.6% for ChamranII to 8.6% for Sistan genotypes. Applying drainage water as irrigation water can cause negative effects on farm soil quality in short term and studying of this behavior by using simulating models can be very useful. For reduction of negative effect of drainage water on soil quality, it is necessary to pay enough attention to the amount and time of irrigation at the last 2 or 3 irrigation events.
Salinity stress
Mohammad Hassan Sayyari Zahan; Mohammad Hossein Sayyadi Anari; GholamReza Zamani; Sohrab Mahmoodi; Farzane Golestanifar
Abstract
IntroductionToday in many parts of the world and specially in Iran, water and soil salinity is one of the environmental stress and a serious risk to plant growth and crop production. One way to modify the salinity of irrigation water for agriculture, identification and application of different types ...
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IntroductionToday in many parts of the world and specially in Iran, water and soil salinity is one of the environmental stress and a serious risk to plant growth and crop production. One way to modify the salinity of irrigation water for agriculture, identification and application of different types of algae. The aim of this experiment was to investigate the effect of two types of algae on the growth characteristics of wheat and basil under salinity stress. Materials and methodsThis research was carried out as factorial in two phases of laboratory (in the form of a completely randomized design) and greenhouse (in the form of a randomized complete block design) in the Faculty of Agriculture of University of Birjand located in Amirabad campus in 2015. The first factor is salinity with four levels (1250, 2500, 5000 and 10000 μs cm-1 in both laboratory and greenhouse sections and the second factor is the application of algae with 3 levels (green-blue microalgae Spirulina platensis (for saline water)), single-celled algae Chlorella vulgaris (for fresh water) and control no use of algae. Algae were grown separately in water salinity treatments described above in 50 × 50 cm aquariums in the laboratory. The soil was well mixed with a small volume of saline solution as required and water added to maintain soil moisture at 0.18 cm3 cm–3 (35% water-holding capacity), and then soil was incubated for 1 weeks for subsequent use in the pot experiment.Results and discussionIn the part of laboratory experiment, the results of analysis of variance showed that there was a significant difference between different levels of salinity stress and algae type on dry weight of plumule and rootlet in wheat and basil, but there was no statistically significant difference between their interactions. The application of algae caused a significant increase in the dry weight of plumule and rootlet wheat. The highest dry weight was obtained in the application of Chlorella algae (0.0125 and 0.0008 g pl-1 per plumule and rootlet, respectively). However, both of algae reduced significantly the dry weight of plumule and rootlet of basil. In pot experiment, the results of variance analysis showed that algae type (P <0.05) and different levels of water salinity (P <0.01) had a significant effect on wheat plant height and for basil just were significant different salinity levels (P <0.01) but their interaction had no significant effect on the trait. The use of algae increased significantly the wheat height (algae Chlorella 9.34% and the use of algae spirulina 6.56%). The interaction effect of algae type and salinity levels (P <0.01) were significant in wheat dry weight but for basil dry weight the simple effect was significant. Results indicated that the interaction of algae type and salinity stress had a significant effect on electrolyte leakage of wheat and basil.ConclusionTherefore, it can be concluded that the type of algae had a different effect on the two types of plants, so that for wheat plant chlorella algae and for basil plant type of spirulina algae had more effect on traits and moderated the effects of salinity stress.
Salinity stress
Raziyeh Baladi; Majid Nabipour; Masumeh Farzaneh
Abstract
IntroductionCaper (Capparis spinosa) is used as multipurpose and adaptable plant which provides a valuable opportunity to enhance greenery and prevent soil erosion in harsh climatic areas. This plant is tolerant of salinity and blooms along the coast. Due to the recent severe drought in Iran and most ...
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IntroductionCaper (Capparis spinosa) is used as multipurpose and adaptable plant which provides a valuable opportunity to enhance greenery and prevent soil erosion in harsh climatic areas. This plant is tolerant of salinity and blooms along the coast. Due to the recent severe drought in Iran and most of the arid and semi-arid regions of the world, farmers have tried to grow drought and salinity tolerant plants (such as capper) instead of plants with high water requirements. Salinity is one of the most common non-Biotic stresses in arid and semi-arid regions, which causes a significant reduction in photosynthesis, which depends on photosynthetic tissue and photosynthetic pigments, so that the general growth traits in Plants are reduced. The present experiment was performed to determine changes in physiological and biochemical properties as well as the ratio of sodium ions to potassium under salinity stress to evaluate salinity resistance and determine the best planting date for capper plant. Also, by obtaining the results of this research, capability, position of development and promotion of this plant in erodible and saline lands that have become the center of fine dust to be determined.Materials and methodsIn order to a experiment was arranged as split plot based on randomized design complete block with three replicatione in the research farm of the Faculty of Agriculture, Shahid Chamran University of Ahvaz in 1397-98 crop year. Treatments include six planting dates as the main factor (7 October, 6 November, 6 December, 5 January, 4February and 6 March) and the sub-factor including four salinity levels (control (urban water), 15, 30 and 45 dS m-1). In this study, was used mechanical scraping method using sandpaper and then placing the seeds in gibberellic acid solution at a concentration of 1500 mg / l to remove the dormancy of the seeds. In the 8-leaf stage, salinity test was started. Sodium chloride salt was used to prepare salinity treatments. To prevent sudden shock to the plants, salinity treatments were applied gradually. Measurements for this experiment began ten days after the highest salinity stress level was applied.Results and discussionBased on the results of this study, the planting dates of 7 October and 6 November were selected as the two best planting dates and the planting dates of 4 February and 6 March were Deleted due to low germination percentage and insufficient number of plant samples from the experiment. The results indicated that salinity had a significantly negative effect on chlorophyll content of caper seedlings while carotenoid content in caper seedlings was significantly increased. The amount of reduction in chlorophyll a content is greater than that of chlorophyll b. protein content decreased and malon dealdehyde increased under salinity stress. Salinity had a significant effect on net photosynthesis. Comparison of the mean effect of salinity on net photosynthesis showed that with increasing salinity level, the amount of net photosynthesis decreased. The highest rate of net photosynthesis was related to the control treatment and the lowest rate of net photosynthesis was related to salinity levels of 30 and 45 dS m-1, which did not show a significant difference with each other. Antioxidant enzyme activity; superoxide dismutase (SOD), catalase (CAT), peroxidase (POD) and ascorbate peroxidase (APX) also increased in response of salinity. The highest amount of reaction to salinity is related to superoxide dismutase enzyme and the other three enzymes showed less reaction to salinity so that for 30 and 45 dS m-1levels there was no significant difference with each other but their highest amount of activity is related to this Levels are 30 and 45 dS m-1 and the lowest level of activity is related to the control treatment. Our observations of ionic content in the aerial organ showed that the sodium content (Na+) increased with increasing salinity, and Athe potassium content (K+) decreased, but in each level of salinity the amount of sodium was lower than potassium. The results of physiological characteristics and Na+/K+ ratio showed that the caper plant is an almost salinity tolerant species (up to 15 dS m-1) which can be a suitable option for successful propagation in arid, semi-arid and saline environments and prevent soil erosion in these areas. Therefore, the use of this plant due to its flexibility to salinity and drought can be a valuable opportunity to increase the green area and prevent provide soil erosion and reduce the negative effects of the dust phenomenon, especially in the south and southwest regions.
Salinity stress
Fatemeh Shakeri; Somayeh Rastegar; Hamed Hassanzadeh Khankahdani
Abstract
IntroductionQuinoa, Chenopodiom quinoa Willd., is an annual plant native to South America and the Andes mountains. It is a plant from the spinach and sugar beet family and despite its high nutritional value it can be cultivated well and produces a suitable crop in conditions where lands have low or limited ...
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IntroductionQuinoa, Chenopodiom quinoa Willd., is an annual plant native to South America and the Andes mountains. It is a plant from the spinach and sugar beet family and despite its high nutritional value it can be cultivated well and produces a suitable crop in conditions where lands have low or limited fertility. Due to the high tolerance of quinoa to salinity stress, this plant was selected for cultivation with unconventional water sources. Given the lack of conventional water in Iran, especially in the southern regions, the use of unconventional water and the identification of tolerant plants with the ability to grow in saline conditions are important. Accordingly, due to the limitation of non-saline water, the use of sea water in coastal areas and low-yield lands can lead to agricultural prosperity in these areas.Materials and MethodsThis investigation was conducted with the aim of evaluating the effect of different concentration of the diluted sea water on germination traits and some morphological parameters of three quinoa cultivars including Red-Carina, Q26, and Q29 as factorial arrangement in completely randomized design with six replications. The used different concentrations of salinity in this study were 1.5 (control), 3, 6, 9, 12, and 15 dsm-1. To evaluate the germination traits, seeds were sown in petri dishes and then 10 ml of different salinity levels were added and petri dishes were placed at 25 °C for one week and the number of germinated seeds was recorded daily. The radicle exit was the criterion for germination. At the end of the period, germination percentage, germination rate, mean daily germination, peak value, and germination value were recorded. To investigate the effect of salinity on the morphological characteristics of quinoa, seeds were sown in the pots containing field soil at a depth of 1.5 to 2 cm. After sowing the seeds in the pots, irrigation with tap water was done until the germination stage according to the plant's water requirement. After ensuring the establishment of the plants (in the 4-leaf stage), salinity treatments were applied. Then the different traits such as the plant height, the number of lateral branches, the number of leaves, the length and width and area of the leaves, the length of inflorescence and seed weight were measured. The obtained data were analyzed using SAS 9.1 software and the means were compared using PLSD at p<0.01.Results and DiscussionBased on the results of analysis of variance, there was a significant difference between the studied cultivars (p<0.01) in terms of germination percentage, germination rate, mean daily germination, and germination value, but salinity had no significant effect on germination percentage. The results also showed that no significant interaction between salinity and cultivar was observed in the percentage and germination rate as well as the peak value. The results of analysis of variance showed that the effects of salinity and cultivar on different morphological properties measured at p<0.01 were statistically significant, but the interaction of cultivar and salinity was significant only on the leaf length, width and area. The results showed that with increasing salinity from 9 to 12 and 15 dsm-1, a non-significant decrease was observed in germination rate compared to the control. With increasing salinity up to 15 dsm-1, the plant height, number of lateral branches, number of leaves, leaf length, and leaf area decreased and the highest yield was related to Q26 cultivar. Compared to the other two cultivars, the Q26 cultivar showed less sensitivity to salinity conditions in different traits such as leaf size and number, number of lateral branches, height before and after flowering.ConclusionIn general, it can be said that salinity did not have an adverse effect on the germination rate of quinoa seeds and in some cases accelerated germination. However, at high salinity level, it affected some vegetative traits such as leaf and branch characteristics and inflorescence length. It seems that by performing a proper management in the field, the establishment and growth of this plant at levels of salinity can be guaranteed.
Physiology of crops under stress conditions
Majedeh Neisi; Baratali Fakheri; Esmaeil Ebrahimie; Abbasali Emamjomeh; Javad Zahiri; Masoud Parvizi Almani
Abstract
IntroductionCold is one of the most important and primitive factors limiting plant growth, especially tropical and subtropical plants. Sugarcane is a tropical and subtropical plant that produces 70% of the total world's sugar. So its impact on the global economy is transparent and undeniable. The main ...
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IntroductionCold is one of the most important and primitive factors limiting plant growth, especially tropical and subtropical plants. Sugarcane is a tropical and subtropical plant that produces 70% of the total world's sugar. So its impact on the global economy is transparent and undeniable. The main problem with most sugarcane cultivars is their extreme sensitivity to cold, which reduces the yield, sugar content and quality of their syrup. The long-term meteorological statistics of Khuzestan province in the past years, show that temperatures below 0°C occur in the sugarcane cultivation and industries almost every year. This factor has a direct effect on reducing sugar production as well as reducing final income. Among the commercial varieties of sugarcane, “Saccharum officinarum var CP69-1062” cultivar has high yield and produces a lot of sugar, but its main problem is its sensitivity to cold and encountering with this stress, which may reduce the yield and content of sugar that can be extracted from it. In contrast, “Saccharum spontaneum” is a wild cultivar with high sucrose content and resistant to biotic and abiotic stresses such as cold stress. So, according to aforementioned, this study was conducted to investigate the effect of cold stress on morphological, physiological and biochemical traits of two sugarcane cultivars CP69-1062 (cold-sensitive) and S. spontaneum (cold-tolerant) under controlled conditions, to: (1) Reporting putative Cold-tolerance cultivars, Aiming to expand their production and use them in breeding programs such as backcross and producing new tolerant cultivars, (2) Reporting The most important traits affected under cold stress and (3) Reporting stable traits under normal and cold stress conditions. Materials and methodsThe experiment was performed as factorial experiment in a completely randomized design with three replications in the tissue Culture and biotechnology Laboratory and Research Greenhouse of Khuzestan Sugarcane Development Research and Training Institute, and cold chamber in the 2019-2020 crop year. To apply cold stress, sugarcane seedlings were placed in cold chamber and exposed to 0°C and -4°C for 24 hours. After the end of the stress period, sampling and analysis were immediately performed. Finally, morphological, physiological and biochemical traits of stressed and control samples such as malondialdehyde content (MDA), electrolyte leakage (EL), leaf pigments, catalase (CAT), peroxidase (POD), ascorbate peroxidase (APX), supraxide Dismutase (SOD), proline and total water soluble carbohydrates (Wsc) of the leaf were measured. Results and discussionThe first effects of cold stress were observed on photosynthesis pigments among all cultivars. However, the sensitive cultivar had a greater reduction compared to tolerant cultivar. Cold stress significantly increased electrolyte leakage (EL) and malondialdehyde (MDA) content from 25 to -4°C in all cultivars, particularly in sensitive cultivar. Moreover, proline content and total water-soluble carbohydrates (WSC) of leaf showed significant increased under cold stress, particularly in tolerant cultivar. Under cold stress, Catalase (CAT) activity significantly decreased compared to control temperature, which was accompanied with negative correlation with proline content. In addition, Superoxide dismutase (SOD), Peroxidase (POD) and Ascorbate peroxidase (APX) activity was higher than control temperature in all cultivars, particularly in tolerant ones. The intensity of these changes were less at -4°C due to intracellular freezing, ice crystals formation and the abolition of cellular metabolic activities. Phenotypicaly, at 0°C, the leaves of the tolerant cultivar showed little change in appearance in comparision with control temperature (25°C). On the other hand, at -4°C the effects of seedling damage were clearly observed. ConclusionsThe results showed that both sensitive (S. officinarum var CP69-1062) and tolerant (S. spontaneum) cultivars had different morphological, physiological and biochemical responses under cold stress compared to control temperature and to each other, that this case indicates different genomic structure, genetic capacity, and their other characteristics in cold tolerance. In addition, S. spontaneum cultivar had better and more efficient defense mechanism than commercial variety CP69-1062 and thus, was more tolerant to cold stress. Finally the set of these physiological and biochemical changes in both sensitive and tolerant cultivars, is to maintain survival and yield under cold stress.
Physiology of crops under stress conditions
Jafar Nabati; Ali Akbar Mahmodi; Syadeh Mahbobe Mirmiran; Saeed Feyzabadi; Mohammad Mohammadi; Ahmad Nezami
Abstract
IntroductionLentil is usually sowned in late winter and early spring. In this conditions, flowering and seed filling stage usually coincide with late drought stress and high temperature which reduce seed yield. Therefore, supplemental irrigation at the end of the growth season is necessary to overcome ...
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IntroductionLentil is usually sowned in late winter and early spring. In this conditions, flowering and seed filling stage usually coincide with late drought stress and high temperature which reduce seed yield. Therefore, supplemental irrigation at the end of the growth season is necessary to overcome this problem. But since in Iran, lentil is mostly cultivated as a rainfed crop in mountain areas and slopes, supplemental irrigation is impossible. By autumn cultivation, plant maturity could be accelerated and higher efficiency of precipitation use, coincidence of growth stages with favorable weather conditions and finally increasing plant height and yield could be achieved. On the other hand, autumn cultivation exposes the plants to sever winter coldness; so, using freezing tolerant cultivars is necessary. The aim of the present study was to identify the role of antioxidants and physiological parameters in improving the cold tolerance of lentil genotypes in controlled conditions.Materials and methodsThe study was conducted in autumn and winter of 2018 in research greenhouse of research center for plant sciences, Ferdowsi University of Mashhad, Mashhad, Iran. the experiment was conducted as factorial based on completely randomized design with three replications in controlled conditions. Experimental factors were consisted of 20 lentil genotypes and three freezing temperatures (0, -18 and -20⁰C). Seeds were sown in October and Seedlings were kept in a natural environment for four months and then were transferred to a thermogradiant freezer. Gas exchange parameters (photosynthesis rate, evapotranspiration, substomatal CO2 concentration, stomatal and mesophilic conductance) as well as water use efficiency, relative water content of leaf, photosynthetic pigments, DPPH radical scavenging activity, Anthocyanin, total phenol and soluble carbohydrates were measured before the plants were exposed to freezing temperatures. Survival percentage, plant height, leaf area and plant dry weight were measured four weeks after freezing stress. Lethal temperature 50% of plants according to the survival percentage (LT50su), Reduced temperature 50% of height plant (HT50), Reduced temperature 50% of leaf area (RLAT50) and Reduced temperature 50% of dry matter (RDMT50) were also determined.ResultsResults indicated that in -18⁰C, 14 genotypes had 100% survival while in -20⁰C, all the genotypes were killed. Based on the studied parameters, lentil genotypes were divided in four groups by cluster analysis. Survival percentage in first, second and fourth group was superior compared to the total average. According to the antioxidant activity, metabolites and pigments concentration, plant height, leaf area and dry weight, genotypes in the first (MLC84, MLC407, MLC454) and second (MLC38, MLC303, MLC74, MLC334) groups were relatively superior compared to the other groups. Principal component analysis (PCA) showed that the first component explained 32.77% of changes in water use efficiency, carotenoids, chlorophyll a/b ratio, mesophilic conductance, photosynthesis, survival percentage, plant height, leaf area and dry weight while the second component explained 16.31% of changes in the concentration of chlorophylls a and b, total pigments, soluble carbohydrates, DPPH radical scavenging activity, phenol, anthocyanin, osmotic potential, evapotranspiration and stomatal conduction. Genotypes of MLC74, MLC334, MLC11, MLC84, MLC454 and MLC407 were better in terms of antioxidant capacity and metabolites and MLC303, MLC17, MLC38, MLC286and MLC469 were superior according to the survival percentage and regrowth.ConclusionThe correlation between concentration of chlorophyll b, carotenoids and photosynthesis rate with survival percentage showed that these traits are suitable indicators for determining cold tolerance of lentil genotypes before exposing to freezing stress. Results of cluster analysis and group mean comparison also indicated the relative superiority of MLC84, MLC407, MLC454 and second MLC38, MLC303, MLC74, MLC334 in most studied parameters. Generally, these genotypes are recommended to be used for complementary studies of freezing tolerance in field conditions in cold regions.
Breeding plants for stress conditions
Ali Barati; Hassan Zali; Shirali Koohkan; Akbar Marzoqian; Ahmad Golipor
Abstract
IntroductionBarley is unique among crop plants for being of tremendous importance to agriculture and to science. Advances on both fronts create a positive feedback loop, allowing barley to be in the forefront in meeting the great challenges of climate change and human population growth. In terms of agriculture, ...
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IntroductionBarley is unique among crop plants for being of tremendous importance to agriculture and to science. Advances on both fronts create a positive feedback loop, allowing barley to be in the forefront in meeting the great challenges of climate change and human population growth. In terms of agriculture, barley is the fourth most important cereal crop in the world. Barley grain, in the form of malt, is the perfect nutritional source for yeast and is therefore the base of the brewing industry. Selection index of ideal genotype (SIIG) technique was improved as following method to the selection of favorable genotypes using different morphological traits simultaneously.Materials and methodsIn order to study the phenotypic diversity of inbred barley lines under heat stress conditions at the end of the season, 108 pure line in the non-repeating Augment design with four controls (Nimroz/Sahra, Norooz, Auxin and WB-95-19) in three blocks, in the Center for Agricultural Research and Education and Natural Resources Fars (Darab), Ahvaz, Sistan (Zabol) and Golestan (Gonbad) were evaluated during 2018-19 cropping year. Plots consisted of six rows that were 6 m long with spacing of 0.20 m between rows. Seeding rate was 300 seeds/m2 at each trial. Agronomic practices including fertilizer application and weed management were carried out as recommended at each location. Following harvest, grain yield (kg ha-1) was determined for each genotype at each testing environment.Results and discussionThe results of REML analysis showed that the highest heritability of yield was related to Gonbad (0.952) and Ahvaz (0.530), respectively, and the heritability of grain yield was close to zero in Darab region and 0.111 in Zabol. The results of SIIG index in Darab showed lines number 8, 33, 34, 64, 32, 6, 2, 113, 15, 13, 119, 9, 28, 87, 115, 85, 65, 14,16 22, 86, 3, 10 and 89 were the best lines with the highest value of SIIG index (0.800-600), respectively. In Ahvaz, lines 113, 119, 109, 19, 83, 110, 90, 82, 120, 98, 118, 17, 106, 102, 40, 42, 23 and 18, with the highest amount of SIIG (0.600-0.600) were the best lines. In Zabol, lines 120, 17, 28, 18, 33, 24, 30, 104, 34, 22, 105, 14, 19, 118, 15, 38, 119 and 16 with the highest value of SIIG index (0.600-0.800) respectively, were the best lines. Lines number 47, 46, 112, 86, 85 and 83 with the highest value of SIIG index (0.900-0.600) were the top lines in this experiment in Gonbad region.ConclusionIn total, based on the average results of SIIG index in all regions, lines number 113, 33, 104, 119, 17, 2, 18, 23, 28, 120, 106, 112, 86, 34, 102, 47, 15, 85, 16, 19, 57, 118, 103, 46, 24, 98, 105, 40 and 22 with the highest average value of SIIG index (0.700-500), respectively, are the best lines in most regions. This research showed that the SIIG index was able to categorize the genotypes according to the different traits, simultaneously. The SIIG method is comprehensive in the order in which amount of information increases. It is very effective in selection of ideal (best) genotypes using several different traits or indices simultaneously. Therefore we propose that researches use of SIIG method to study of genetic variation and help to choose ideal genotypes using morphological and physiological traits, simultaneously.
Heavy metals
Shahrzad Hosseini; Nasser Zare; Parisa Sheikhzadeh; Shahrbano Abootalebi
Abstract
IntroductionEnvironmental pollution with heavy metals has spread in the world. The impact these pollutants on the human health and food chain, as one of the factors of economic and health concerns, needs more attention. Cadmium (cd) as one of the most important heavy metals compared to other metals is ...
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IntroductionEnvironmental pollution with heavy metals has spread in the world. The impact these pollutants on the human health and food chain, as one of the factors of economic and health concerns, needs more attention. Cadmium (cd) as one of the most important heavy metals compared to other metals is rapidly absorbed and accumulated in plant tissues, and its transfer to the food chain is the result of widespread contamination of the soil with cadmium. Nano-silicon (Si) is more effective than usual fertilizers in protecting plants against biotic and abiotic stresses. Medicinal plants are one of the most important sources of drug production that humans have used for many years, and their importance is expanding day by day. Many secondary metabolites of Borago officinalis and its products are consumed in the world pharmaceutical markets, so it requires special attention to improve the quality of culture, production efficiency, and health. This attention requires increasing knowledge about the physiological mechanisms of this plant affected by environmental factors such as cadmium stress. This study aimed to investigate the effect of nano-silicon on alleviating the detrimental effects of cadmium stress on physiological properties such as antioxidant enzyme activity in Borago officinalis.Materials and methodsTreatment was performed by adding cadmium in the form of cadmium nitrate (Cd (NO3)2) and nano-silicon in hydroponic cultures of borage plants at the 7-8 leaf stage. This study was conducted as a factorial experiment based on a completely randomized design with three replications. Experimental factors were cadmium at three levels (0 (control), 25 mg L-1, and 75 mg L-1) and nano silicon at two different levels (0 and 1.5 mM). One day, one week, and two weeks after treatment, plant leaves were sampled and the amount of cadmium accumulation and biochemical and physiological properties were measured.Results and discussionThe results showed that the accumulation of cadmium in the aerial parts of the borage plant was significantly increased with increasing the cadmium concentration in the hydroponic medium. The utilization of nano-silicon significantly reduced the amount of cadmium absorption and accumulation in borage plants.Cadmium nitrate increased the amount of hydrogen peroxide compared to the control. The use of nano-silicon significantly reduced the amount of hydrogen peroxide under cadmium stress at one and two weeks after treatment. One of the important consequences of increasing the concentration of heavy metals in plants is increasing in the production and accumulation of reactive oxygen species (ROS) such as superoxide, hydroxyl and hydrogen peroxide (H2O2) radicals in the cells. This reactive oxygen species leads to the oxidation and destruction of macromolecules such as protein, DNA, cell membrane damage and ion leakage.With increasing the concentration of cadmium, the amount of malondialdehyde (MDA) and proline in the cells were significantly increased. Malondialdehyde (MDA) and proline levels were significantly reduced by nano-silicon treatment. Heavy metals such as cadmium lead to the production of hydroxyl radicals, followed by lipid peroxidation. With increasing the lipid peroxidation, the cell membrane is destroyed and malondialdehyde levels increase. In the present study, the amount of malondialdehyde was significantly reduced under the influence of nano- silicon treatment. Proline accumulation in plants may also be a biomarker of cadmium stress, because proline can scavenge free radicals and protect the cells from their damaging effects.With increasing the concentration of cadmium, the activity of polyphenol oxidase, peroxidase, and catalase enzymes was increased. In addition, the activity of these enzymes was reduced with the utilization of nano-silicon. The highest activities of these enzymes were recorded under cadmium concentration at 75 mg l-1 and the lowest activities of these enzymes were related to the treatment of nano-silicon and control. Increasing the level of antioxidant activity can sweep ROS produced by heavy metals, and protects the cell from the damaging effects of oxidative stress, which increases the plant's tolerance to environmental stresses, including heavy metals. The use of nano-silicon positively reduces cadmium accumulation in the plant maybe by maintaining the photosynthetic capacity and regulating the uptake and transfer of cadmium under cadmium stress conditions. On the other hand, nano-silicon reduces the amount of malondialdehyde (MDA) and reactive oxygen species (H2O2) may be through the reduction of cadmium uptake and accumulation in the plant cells and tissues as well as increase in the efficiency of enzymatic and non-enzymatic antioxidant systems.ConclusionsThe results of the present study showed that the accumulation of cadmium in the borage tissues under cadmium stress was reduced due to the application of nano-silicon. In other words, the use of nano-silicon improved the physiological characteristics of the borage plant by reducing the uptake and transfer of cadmium nitrate. This reduction in the amount of uptake and accumulation of cadmium nitrate in plant tissues is important for the health of agricultural products and human communities.
Lila Froghi; Serallah Galeshi
Abstract
Flooding stress is one of the most important stresses related to autumn plants especially in the northern parts of the country. The most cost-effective and reliable way to reduce the effects of environmental stresses on crops is to choose a resistant cultivar. Therefore, this experiment was conducted ...
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Flooding stress is one of the most important stresses related to autumn plants especially in the northern parts of the country. The most cost-effective and reliable way to reduce the effects of environmental stresses on crops is to choose a resistant cultivar. Therefore, this experiment was conducted to investigate Flooding stress tolerance in wheat genotypes using some morphological and physiological characteristics and its relationship with grain yield. This experiment was conducted as a factorial experiment in a completely randomized design with 3 replications and two factors: 1) Flooding stress (non-flooding and 15 days flooding) and 2) cultivar (20 cultivars) at Gorgan University of Agricultural Sciences and Natural Resources in 2016-17. Done. Based on the results of this experiment, the highest grain yield was observed in N-80-19, N-87-20 and N-91-14 under non-stress conditions, which were 1.95 and 1.88 g pl-1, respectively. Under flooding conditions, the highest grain yield was obtained in N-80-19 (1.02 g pl-1) and Kohdasht (0.96 g pl-1) cultivars. The results showed that leaf area, leaf dry weight, chlorophyll a and b, root volume and dry weight, carotenoid and SPAD were affected by the destructive effects of Flooding stress and were significantly reduced under non-stress conditions. Leaf area had the highest correlation (0.89) with grain yield, after leaf area, chlorophyll a and SPAD had the highest correlation with grain yield. Based on the results of this experiment, it can be concluded that leaf area, photosynthetic pigments, SPAD number and root volume in wheat genotypes were highly correlated under water stress conditions with wheat grain yield, Therefore, genotypes with more photosynthetic leaf area at vegetative stage can be identified as resistant genotypes to Flooding stress. Carotenoid and SPAD were affected by the destructive effects of Flooding stress and were significantly reduced under non-stress conditions. Leaf area had the highest correlation (0.89) with grain yield, after leaf area, chlorophyll a and SPAD had the highest correlation with grain yield. Based on the results of this experiment, it can be concluded that leaf area, photosynthetic pigments, SPAD number and root volume in wheat genotypes were highly correlated under water stress conditions with wheat grain yield, Therefore, genotypes with more photosynthetic leaf area at vegetative stage can be identified as resistant genotypes to flooding stress.
