Seyedeh Samira Hosseini; Seyed Hossein Nemati; Hossein Aroiee; Ahmad Nezami
Abstract
IntroductionSweet pepper is a rich source of essential vitamins and minerals. On the other hand, pepper fruit contains high levels of antioxidants and beneficial substances such as vitamin C, carotenoids and phenolic compounds. It also contains high concentrations of potassium. These compounds has nutritional ...
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IntroductionSweet pepper is a rich source of essential vitamins and minerals. On the other hand, pepper fruit contains high levels of antioxidants and beneficial substances such as vitamin C, carotenoids and phenolic compounds. It also contains high concentrations of potassium. These compounds has nutritional and antioxidant capacity. Sweet pepper originated from the tropical region, which is sensitive to cold. Therefore, it is necessary to know the defense mechanism of the pepper plant against low temperatures. In this study, the effect of foliar application of salicylic acid and vermicompost on different cultivars of sweet pepper under cold stress has been studied.Materials and methodsThe experimental design was a factorial split-plot experiment in a randomized complete block design with three replications in a greenhouse located in Mashhad in the crop year 1396 and 1397. Cultivation was performed hydroponically. The main factor of temperature treatment had two levels [9 ± 2°C (cold stress) and 23 ± 2°C (optimum)] and the sub factor consisting of two sweet pepper cultivars (green, yellow) and Different amounts of Salicylic acid (The dose of 0 μmol salicylic acid was used as control group, 200, 300 μmol) and vermicompost). Sampling of the plants at the end of the growing season, to measure the physiological characteristics and quality were randomly.Results and discussionThe results showed that there was no significant difference between different cultivars in most traits except vitamin C, beta-carotenoids and lycopene. Maximum dry matter (17.2g), TA (13.6 g l-1) in non-stress cold treatment, and soluble solids (5.03 brix),, carbohydrates(174.5 mg g-1), and anti-activity Oxidation (90.3%) were obtained in cold stress treatment. Damage due to cold stress destroyed the structure of many membrane lipids and resulted in an increase in the amount of antioxidant compounds. Soluble solids are known to be key components in increasing cold resistance. An increase in the amount of soluble solids in winter is part of the plant's adaptation mechanism to cold. The highest yield of fruit per plant(740 g) was obtained in non-cold stress treatment plus salicylic acid 300 μmol. Because salicylic acid in plants improves yield and yield components. Maximum of flavonoids (159.4 mg g-1) was obtained in salicylic acid 200 μmol. Flavonoids are a large group of phenolic compounds in plants that increase their production in environmental stresses by increasing the activity of PAL enzyme. On the other hand, the use of salicylic acid as a stressor causes the production of a wide range of flavonoids. The highest amount of beta-carotene and lycopene were obtained in cold stress treatment, yellow cultivar, and salicylic 300 μmol. Decreased content of carotenoids under stress can be due to oxidation by active oxygen and damage to their structure. Increased photosynthetic pigments under SA treatment indicate the protective effect of this growth regulator on photosynthesis and photosynthetic pigments of stressed plants. Maximum vitamin C was obtained in cold stress treatment (140.7 mg 100 g-1, yellow cultivar (134.7 mg.100g-1), and salicylic 300 μmol (142.52 mg.100 g-1).ConclusionAccording to the results, the of the present study show that use of salicylic acid foliar application modulates the effect of cold stress on the physiological and functional parameters of sweet pepper so that SA can improve cold tolerance by regulating the activities of apoplastic antioxidative enzymes. Therefore, it is suggested that due to sudden changes in temperature due to climate change and the destructive effects of temperature stress, especially cold, on plants, more and more complete research should be done to identify the effects of these stresses and ways to deal with them.
Breeding plants for stress conditions
Reza Amiri; Sohbat Bahraminejad; Kianoosh Cheghamirza
Abstract
IntroductionIn Iran, as in most poor and developing countries, wheat is the most important food in the diet of the people. Therefore, the field of study and research on various aspects of this important and strategic crop is still open to relevant researchers and experts. Given that the achievement of ...
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IntroductionIn Iran, as in most poor and developing countries, wheat is the most important food in the diet of the people. Therefore, the field of study and research on various aspects of this important and strategic crop is still open to relevant researchers and experts. Given that the achievement of yield potential in crops, including wheat, is influenced by genetics, environmental conditions, their interaction and the application of proper management in the optimal use of available resources, so the genetic capacity of the existing germplasm should be used to produce suitable breeding lines in order to make the most of natural and climatic resources. Therefore, screening genotypes, selecting the proper parents, and modifying them through conventional and new methods can still be helpful. Estimating genetic effects and studying the inheritance pattern of important agronomic traits and in general knowledge of germplasm genetic information and knowledge of the genetic system of the studied trait is one of the most useful tools in designing breeding methods to improve target traits. This study aimed to estimate the genetic model controlling important agronomic traits and also to estimate heterosis and heritability in two bread wheat cross under normal and terminal drought stress conditions using generation mean analysis method and multivariate regression analysis.Materials and methodsA field investigation materials consisted of basic generations obtained from the crosses of a local cultivar “Marvdasht” (female parent) with two cultivars “Sistan” and “Norstar” (male parents). Both the crosses and resultant progenies were performed and developed under field conditions. All the six generations derived from the above two crosses were sown under two distinct conditions, normal (non-stress) and terminal drought stress in a randomized complete blocks design with three replicates at the Research Farm of Razi University, Kermanshah, Iran during the next cropping season (2015-2016). Terminal drought stress was imposed in Mid-May; while non-stress plots were irrigated whenever required. Weeds were controlled manually when necessary. The rainfall in 2015-2016 was 653 mm. Data from 10 plants in each of P1, P2 and F1 generations, 30 plants in F2 and 15 plants in each of BC1 and BC2 were randomly recorded per replication. Statistical analyses were done using different methods and software.Results and discussionSignificant differences between the generations were found for most of the traits which indicated the presence of genetic variation in the plant populations and scope of improvement through breeding methods such as selection and expression of heterosis. The scaling and joint scaling tests revealed that the simple additive-dominance model was not sufficient to explain the genetic variation in the crosses for all the studied traits apart from the number of spike per plant, main stem diameter and number of spikelet per spike at Marvdasht × Sistan, and hundred kernel weight and peduncle length at Marvdasht × Norstar. It could be concluded that the inheritance of these traits is governed by epistasis gene action. The results of analysis of variance obtained by regression method showed that fixable genetic effects had the highest relative contribution of the generation sum of squares for most of the traits in both crosses and under both normal and drought stress conditions. High estimates of broad-sense heritability for hundred kernel weight (0.67) in normal conditions at Marvdasht × Sistan cross and plant height (normal: 0.76 and stress: 0.67) and peduncle length (normal: 0.72 and stress: 0.67) at the Marvdasht × Norstar cross shows that the effects of dominance have a greater role in the inheritance pattern of these traits and therefore it is possible to produce hybrid varieties to improve these traits.ConclusionThe results of generation mean analysis showed that the type and action of genetic effects were variable in both crosses and for different traits and indicate the need to adopt a special breeding method to improve them. The presence of duplicate mode of gene interactions signified the involvement of epistatic effects for most of the traits. Based on the present investigation, it could be inferred that the genetic control model was somewhat similar for most of the traits under both conditions at both crosses, and it has not been largely affected by drought stress.
Drought stress
Alireza Jahanbani; Rasool Asghari Zakaria; Vahid Ashrafi; Marefat Ghasemi Kalkhoran; Reza Shahriary
Abstract
IntroductionDrought is considered one of the most important factors limiting crop performance worldwide. Consumption of humic acid on plants, in addition to soil fertility, increases plant tolerance to drought and soil water holding capacity. Chitosan is also a natural biopolymer modified from chitin ...
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IntroductionDrought is considered one of the most important factors limiting crop performance worldwide. Consumption of humic acid on plants, in addition to soil fertility, increases plant tolerance to drought and soil water holding capacity. Chitosan is also a natural biopolymer modified from chitin and non-toxic, biodegradable, and environmentally friendly substances that acts as a potential stimulant in agriculture. Chitosan and humic acid reduce the negative effects of abiotic stresses. Accordingly, due to the drought crisis in arid and semi-arid regions, in this study, the modulating effect of humic acid and chitosan foliar application on wheat tolerance to drought stress at the end of the season was investigated.Materials and methodsThis experiment was performed to study the effect of foliar application of chitosan and humic acid on improving drought tolerance of wheat genotypes in the form of split split plots based on a randomized complete block design with three replications. The main plot includes irrigation treatments at two levels (full irrigation and cessation of irrigation in spike stage), sub-plots including three wheat genotypes including Mihan, CD-93-9, and CD-93-10, and sub-plots including humic acid and chitosan foliar application levels (Zero, 2 g.L-1 of humic acid, 3 ml.L-1 of chitosan and the combination of humic acid and chitosan). The experiment was carried out on a field in Ardabil Agricultural Research Station. Sowing was done in October 2020 with a planting density of 450 seeds per square meter. Chemical fertilizer based on NPK soil test at 50, 100, and 20 kg.ha-1, respectively was added to the soil before planting. Each genotype was planted in 1.5 cm by 7 m plots. The length of each row was 7 m and the distance between the rows was 20 cm and the seeds were sown at a depth of 5 cm. STAR 2.01 statistical software was used to analyze the data including data analysis of variance and comparison of means by LSD method at a 5% probability level.Results and discussionThe results showed that the interaction effect of cultivar × stress × foliar application was significant in all studied traits including plant height, number of seeds per spike, number of spikes, spike length, and grain yield, except the number of tillers per plant and 1000-seed weight. Regarding the number of tillers per plant, the interaction of cultivar × foliar application was significant and for 1000-seed weight, the interaction of cultivar × stress and stress × foliar application was significant. Although there were differences in the response of wheat genotypes to the foliar application under both stress and non-stress conditions, in most traits such as number of tillers, number of seeds per spike, spike length, plant height, and 1000-seed weight, the best result was the simultaneous use of chitosan and humic acid. Was obtained. Also, both under non-stress and under stress conditions, the highest grain yield of the studied genotypes was obtained in simultaneous foliar application of chitosan and humic acid. In general, it can be concluded that the combination of chitosan and humic acid (2 g.L-1 humic acid and 3 ml.L-1 chitosan) significantly showed the best results in increasing the yield and yield components of wheat compared to the control treatment in both non-stress and the end of the season drought stress conditions.ConclusionFoliar application of humic acid and chitosan increased and improved the studied traits, both under drought stress and non-stress conditions in wheat genotypes compared to non-foliar application. The maximum number of tillers, number of seeds per spike, number of spikes, spike length, 1000-seed weight, and grain yield were obtained by foliar application of chitosan and humic acid under both full irrigation and stress conditions. Therefore, it is recommended to use simultaneous spraying of chitosan and humic acid to increase tolerance and achieve higher performance. Also, the study of different concentrations of these two substances in combination with each other and at different stages of wheat growth can determine the best dose and time of their consumption in this strategic crop, which is recommended to conduct studies in this regard.
Biotechnology and environmental stresses
Abbas Saidi; Zahra Hajibarat
Abstract
IntroductionPotato (Solanum tuberosum L.) is an economic crop that is grown and consumed worldwide. Potato is considered as the fourth important crop for human consumption after maize, wheat, and rice. Potato contain more carbohydrates, proteins, minerals, and vitamins per unit area than cereals. However, ...
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IntroductionPotato (Solanum tuberosum L.) is an economic crop that is grown and consumed worldwide. Potato is considered as the fourth important crop for human consumption after maize, wheat, and rice. Potato contain more carbohydrates, proteins, minerals, and vitamins per unit area than cereals. However, this crops exposed environmental stresses during growth and developmental stages particularly, drought stress. Potato is sensitive to drought condition because of narrow root system. As a result, it is necessary the investigation of molecular mechanism involved in drought stress in potato. Drought stress affected on the integrity and structure maintain of biological membrane. The actin-based myosin is necessary for the growth and organization of the endomembrane system. Given that myosin genes allow to move intercellular and intracellular providing the possibility of repair of damaged membrane areas under drought stress in plants. In eukaryotic cells, organelle movement, positioning and communications are critical for maintaining cellular functions and are highly regulated by intracellular trafficking. Directional movement of motor proteins along the cytoskeleton is one of the key regulators of such trafficking. Most plants have developed a unique actin–myosin system for intracellular trafficking. Myosins participate in a different cellular processes, endocytosis, containing cell polarization, intracellular and organellar transport, transcriptional regulation, and signal transduction. Motions are as molecular motors in biological systems. These can bind to filamentous actin and produce physical forces through hydrolyzing ATP. Myosins is one of the most diverse and largest protein families in eukaryote. Class XI and VIII motor proteins are characterized as a slow and fast motor proteins. Myosin XI possess many genes in Angiosperms. Whereas, myosin-VIII contain fewer members against class XI. Further, molecular size of myosin-VIII is smaller than myosin-XI.Materials and methodsProtein file of A.thaliana was downloaded and matrix file of hidden Markov Model (HMM) of myosin gene family was used. Here, phylogenetic analysis, gene structure, and gene expression were surveyed. Gene expression of two genes (StMyoXI-F and StMyoXI-B) was performed in different tissues (root, stem, leaves, and tuber). For analysis of expression in different tissues (leaves, stem, and root), sampling was performed 2 weeks after mother tuber growth. However, tubers were sampled 6 weeks after cultivated in Karaj. To evaluate expression under drought stress, after 6 weeks of growth, the water stress was induced by irrigation suppression in 2 weeks while, daily irrigation was maintained for control plants. Leaves and tuber sampling were performed under two conditions.Results and discussionThe seven StMyo genes were unevenly distributed in the two subgroups. The seven StMyo genes were unevenly distributed in the two subgroups. Class XI was the largest subfamily, which class VIII had the lowest subfamily. Drought treatment significantly increased expression of StMyoXI-B and StMyoXI-F genes by 80 and 8 fold compared to the control treatment, repectively. Under control conditions, StMyoXI-B and StMyoXI-F enhanced expression in root by 25 and 20 fold while, it showed low expression in leaves under control conditions. Under control conditions, StMyoXI-F gene showed the 3 and 4 fold change higher mean relative expression than the reference gene. The relative expression of StMyoXI-B gene has been increased 5 and 10 fold change in leaves and stem under non-stress conditions as compared to the reference gene. Among myosin genes, the number of exons varied from 1 to 39. Most of class-VIII proteins had fewer introns whereas, class-XI proteins possess more proteins than class VIII. This results indicated that occurred splicing process in the myosin genes.ConclusionBased on the obtained results, it is considered that these genes highly do not influenced in stem development. However, it had significantly affected in root, leaves, and tuber development. It seems this gene can be potentially a good candidate for drought tolerance breeding programs in potato.
Breeding plants for stress conditions
Hamid Reza Babaei
Abstract
IntroductionSelection efficiency requires complete and accurate knowledge of genetic parameters such as heritability, phenotypic and genotypic variation coefficient, environmental variance, selection response, genetic gain, genetic and phenotypic variance, genetic and phenotypic correlation between traits ...
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IntroductionSelection efficiency requires complete and accurate knowledge of genetic parameters such as heritability, phenotypic and genotypic variation coefficient, environmental variance, selection response, genetic gain, genetic and phenotypic variance, genetic and phenotypic correlation between traits that the breeder consciously chooses the appropriate selection method in breeding populations. In this study, some genetic parameters for yield and soybean agronomic and reproductive period characteristics under normal and stress conditions were estimated and drought tolerant genotypes are determined by the Ideal Genotype Selection Index (SIIG).Materials and methodsIn 2013, in an experimental farm in Karaj, 50 soybean genotypes were cultivated in two normal and drought stress conditions in a randomized complete block design with three replications. Irrigation cycle was determined based on the amount of evaporation from the surface of Class A pan. During the growth period, the reproductive period characteristics and after the ripening agronomic traits were evaluated. After collecting experimental data, analysis of variance, mean, minimum, maximum values of traits, heritability, phenotypic and genotypic variation coefficient, environmental variance, selection response, genetic gain, genetic and phenotypic variance, genetic and phenotypic correlation, and SIIG index method was used for grouping genotypes based on drought tolerance.Results and discussionAmong the the reproductive period characteristics the highest and lowest genetic gain in normal conditions were 21.40 and 3.95% for day to the beginning of seed filling and the Reproductive relative duration respectively and in stress conditions were 21.9 and 7.3% for day to the beginning of seed filling and the Reproductive relative duration respectively.In normal conditions, the highest genetic gain was 0.52 for the number of pods per plant and the number of branches and the lowest genetic genetic gain was 0.14 for the number of nodes per stem. In stress conditions, the highest and lowest genetic gain were 104% and 0.14 for the number of pods per plant and the number of nodes per stem, respectively. In normal conditions, among the agronomic traits, the highest values of response to indirect selection of grain yield were 1.6 and 1.41 g, through 100-grain weight and number of seeds per plant respectively and in stress conditions, the highest values of response to indirect selection of grain yield were 1.04, 0.89 and 0.87, through The number of branches, number of seeds per plant and weight of 100 seeds were obtained respectively. Also, according to the Ideal Genotype Selection Index (SIIG), five genotypes were in the tolerant group, seven genotypes in the semi-tolerant group, 11 genotypes in the semi-susceptible group and 27 genotypes in the susceptible group. Roanak, Kabalovskaja and TMS genotypes were identified as the most drought tolerant and AGS 363, Hermen and Kuban as the most drought sensitive genotypes.ConclusionBased on the results, acceptable phenotypic and genotypic diversity in terms of agronomic traits was observed among the studied genotypes. Most of the genetic parameters measured were almost identical under both normal and stress conditions. The characteristics of the reproductive period had higher e selection response (direct and indirect), higher broadsense heretability and higher genetic gain than the agronomic characteristics. The highest indirect to direct selection efficiency for grain yield were obtained from number of seeds per plant and 100-seed weight under normal conditions,and The highest indirect to direct selection efficiencies were obtained from number of sub-branches, number of seeds per plant and 100-seed weight in stress conditions. Also in this study, based on the ideal genotype selection index (SIIG), Roanak, Kabalovskaja and TMS genotypes were identified as the most tolerant and AGS 363, Hermen and Kuban as the most sensitive genotypes.
Breeding plants for stress conditions
Sorour Arzhang; Reza Darvishzadeh; Hadi Alipour
Abstract
IntroductionSalinity stress is one of the main abiotic stress factors and environmental problems affecting crop yields worldwide, especially in arid and semi-arid regions. Land salinization is increasing, with 10 million ha of agricultural land destroyed annually. An increase in the concentration of ...
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IntroductionSalinity stress is one of the main abiotic stress factors and environmental problems affecting crop yields worldwide, especially in arid and semi-arid regions. Land salinization is increasing, with 10 million ha of agricultural land destroyed annually. An increase in the concentration of salts in soil solution or irrigation water adversely affects plant growth and productivity, which can substantially reduce yield production. Maize (Zea mays L.) is the third most important cereal grain after rice and wheat, due to its high yield and nutritive value and also known as the queen of cereal crops and is moderately sensitive to salinity stress. Accurate screening of maize tolerant genotypes using selection indices for salinity stress tolerance is an efficient approach to improve salinity tolerant crop plant genotypes, as well as reduce the effect of salinity on this crop.Materials and methodsThis study was conducted at the Urmia University Research Farm in 2017 to evaluate the influence of salinity stress (8 dSm-1) on the grain yield of 86 maize lines, as well as identify salt-tolerant maize lines based on selection indices for salinity stress tolerance. The pot experiments in normal and salinity stress conditions were set up in a randomized complete block design (RCBD) with three replicates. Ten selection indices for salinity stress tolerance including Stress Susceptibility Index (SSI), Tolerance Index (TOL), Stress Tolerance Index (STI), Mean Productivity (MP), Geometric Mean Productivity (GMP), Harmonic Mean (HM), Abiotic Tolerance Index (ATI), Drought resistance Index (DI), Modified Stress Tolerance Index in normal condition (MpSTI), and Modified Stress Tolerance Index in stress condition (MsSTI) were calculated based on grain yield of lines under normal and salinity stress conditions.Results and discussionA wide range of genetic variability was obtained among the studied maize lines in terms of grain yield under normal and salinity stress conditions as well as in terms of selection indices for salinity stress tolerance, which provided suitable conditions for evaluating tolerance indices and selection of tolerant lines. STI, MP, GMP, and HM had the highest correlation with grain yield in both normal and salinity stress conditions and were suitable to screen salt-tolerant and high-yielding maize lines. The three-dimensional (3D) plot obtained from these indices showed that the lines Ma025, Ma010, Ma026, Ma011, Ma009 Ma015, Ma116, Ma012, Ma028, and Ma062, which were in group A, had high yields in both normal and stress conditions. The results obtained from the use of principal component analysis showed that the first two principal components account for 93% of the total variance. The first component, called yield potential, had a very significant correlation with STI, MP, GMP, HM, DI, MpSTI, and MsSTI and was able to separate high-yielding maize lines in both normal and stress conditions. The second component, called sensitive or tolerant to salinity stress, had a very high correlation with SSI, TOL, and ATI and was able to distinguish stable maize lines. According to the hierarchical cluster analysis, a total of 86 maize lines were grouped in three tolerant, semi-tolerant, and sensitive clusters somehow this clustering was completely consistent with the separation of maize lines by the first principal component. In addition, each of these clusters had two subclusters that were separated according to the second principal component, so that in each cluster, the lines that had high yield stability were placed in the first subcluster, and the lines that had lower yield stability were placed in the second subcluster. Thus, Ma010, Ma026, Ma009, Ma027, Ma023, Ma007, and Ma005 were introduced as salt-tolerant maize lines with stable yields to use in breeding programs.ConclusionBased on the available findings, the present study, as the first study on a large number of maize lines (86 lines) in the country, evaluated salinity stress tolerance using selection indices. The results of this study revealed the importance of using selection indices for stress tolerance as a reliable and useful tool to improve salinity stress tolerance in maize lines. Accordingly, STI, MP, GMP, and HM were identified as the most appropriate indices for the selection of tolerant and stable maize lines using multivariate statistical methods. It is recommended that the selected maize lines be considered as parent lines in future breeding programs in order to improve salinity stress tolerance and stable grain yield.
Drought stress
Alireza Mohseni Mohammadjanlou; Raouf Seyed Sharifi; Saeid Khomari
Abstract
IntroductionWater limitation is one of the most important environmental factors in reducing the growth and yield of wheat due to producing reactive oxygen species and reducing membrane stability (El-Tayeb, 2006). Several strategies have been suggested in order to improve grain yield of wheat under water ...
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IntroductionWater limitation is one of the most important environmental factors in reducing the growth and yield of wheat due to producing reactive oxygen species and reducing membrane stability (El-Tayeb, 2006). Several strategies have been suggested in order to improve grain yield of wheat under water limitation condition, among them use of bio fertilizers and putrescine play a key role in yield improvement. PGPR and Mycorrhiza fungi have the potential to modulate and regulate the physiological and biochemical responses of plants against drought stress, and for this reason, they increase plant survival under environmental conditions (Marasco et al., 2012). Polyamines are another compound that play a significant protective role in plants when environmental stress occurs (Hadi et al., 2016). Foliar of putrescine is able to improve the resistance of plants in oxidative stress and by increasing the activity of antioxidant enzymes, it increases the resistance of plants against oxidative stress (Groppa et al., 2001). A better understanding of physiological responses under water limitation condition may help in programs which the objective is to improve yield of wheat. During the course of these stresses, active solute accumulation of compatible solutes such as proline and the activities CAT, POD and PPO enzymes are claimed to be an effective stress tolerance mechanism. Therefore, the aim of this study was to evaluate the effects of bio fertilizers and putrescine on some the physiological and biochemical responses (i.e., antioxidant enzyme activity, soluble sugars, proline, malondialdehyde (MDA) and hydrogen peroxide (H2O2) content) of wheat under water limitation.Materials and methodsA factorial experiment was conducted based on randomized complete block design with three replications at the research farm, faculty of Agriculture and Natural Resources, University of Mohaghegh Ardabili during 2018-2019. Factors experiment were included irrigation at three levels (full irrigation as control, irrigation withholding in 50% of heading stage and irrigation withholding in 50% booting stage as moderate and severe water limitation respectively) and bio fertilizers at four levels [no bio fertilizer, both application of Psedomunas Putida Strain 186 and Flavobacterim Spp, both application of Mycorrhiza with Psedomunas and Flavobacterim, application of Mycorrhiza], and putrescine foliar application in three levels (foliar application with water as control and foliar application 0.5 and 1 mM of putrescine). Psedomunas putida strain 186 and Flavobacterim spp were isolated from the rhizospheres of wheat by Research Institute of Soil and Water, Tehran, Iran. For inoculation seeds were coated with gum Arabic as an adhesive and rolled into the suspension of bacteria until uniformly coated. The strains and cell densities of microorganisms used as PGPR in this experiment were 1×107 colony forming units (CFU). Mycorrhiza fungi (Glomus intraradices) was purchased from the Zist Fanavar Turan institute. The activity of antioxidant enzymes (catalase, peroxidase and polyphenol oxidase) was measured by Sudhakar et al. (2001) method, soluble sugar content by Dubios et al. (1956) method, measurement of malondialdehyde (MDA) by Stewart and Bewley, (1980) and method of Alexieva et al, (2001) was used to measure the hydrogen peroxide. Proline content was measured by Bates et al. (1973) method. Analysis of variance and mean comparisons were performed using SAS9.1 computer software packages. The main effects and interactions were tested using the least significant difference (LSD) test at the 0.05 probability level.Results and discussionApplication of both Mycorrhiza with Pseudomonas and Flavobacterium and putrescine foliar application under severe water limitation conditions (irrigation withholding in booting) increased the activity of polyphenol oxidase, peroxidase and catalase enzymes. The highest activity of these enzymes were obtained in irrigation withholding in booting stage with application of both Mycorrhiza with Pseudomonas and Flavobacterium and foliar application of 1 mM putrescine and the lowest of values were obtained in full irrigation and no application of bio fertilizers and no putrescine foliar application. The highest rates of proline and soluble sugar were observed under irrigation withholding in heading with the both application of biofertilizers and putrescine and the lowest of them were observed in full irrigation, no application of biofertilizers and no foliar putrescine. Water limitation increased electrical conductivity (EC), malondialdehyde (MDA) and hydrogen peroxide (H2O2) content, while application of bio fertilizers and putrescine under water limitation conditions decreased electrical conductivity, malondialdehyde and hydrogen peroxide content. Application of Mycorrhiza with Pseudomonas and Flavobacterium and foliar of 1 mM putrescine under severe water limitation decreased malondialdehyde and hydrogen peroxide content about 51 and 31.72% respectively compared to no application biofertilizers and putrescine under same water limitation level. In general, water limitation (irrigation withholding in booting and heading) decreased grain yield compared to full irrigation. application Pseudomonas and Flavobacterium (23.1%) and both application of Mycorrhiza with Pseudomonas and Flavobacterium (16.6%) increased grain yield in comparison with no application of biofertilizers under conditions of irrigation withholding in booting. Foliar application 1 mM of putrescine increased grain yield about 8.5% in comparison with no application putrescine.ConclusionIt seems that application of bio fertilizers and putrescine can increase grain yield of wheat under water limitation conditions due to improving physiological and biochemical trait.
Physiology of crops under stress conditions
Mostafa Zangoie; Soheil Parsa; Majid Jami Al-Ahmadi; Ali Izanloo
Abstract
IntroductionCamelthorn (Alhagi camelorum Fisch.) is a perennial plant with shrub growing form belonging to Fabaceae family, which is native to large area from Mediterranean to Russia. Camelthorn is very high tolerant to salinity and this is one of the halophytic plants. By using halophytic plants, many ...
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IntroductionCamelthorn (Alhagi camelorum Fisch.) is a perennial plant with shrub growing form belonging to Fabaceae family, which is native to large area from Mediterranean to Russia. Camelthorn is very high tolerant to salinity and this is one of the halophytic plants. By using halophytic plants, many products can be produced in saline areas, which one of these products is forage needed by livestock. One of the most important areas for the development of camelthorn cultivation is saline lands that have been excluded from cultivation due to irrigation with saline water for many years that increasing soil salinity. Therefore, it is necessary to investigate the plant forage quality in field conditions with irrigation by saline water. Materials and methodsThe experiment was conducted as split-factorial in a randomized complete block design with three replication in two locations (Farms of the Faculty of Agriculture in the Birjand University and Hojjatabad farm of Peyvand Khavaran Agro- Industry in Sarbishe) at years of 1399. The effect of location was considered fixed. The Experimental factors was included ecotype at two levels (Voshmgir and Korond), Plant density at two levels (10 and 20 plant per square meter) irrigation water salinity at 3 levels (3.5, 7.5 and 12 dS/m). The main plots were included irrigation water salinity levels and the sub-plots were included from a combination of density and ecotype levels. The amounts of crude protein, crude fatty acids, crude ash, acid detergent fiber, neutrals detergent fiber, Metabolizable energy, and digestible dry matter of camelthorn forage were measured at the end of the growing season.Results and discussionThe results showed that by increasing salinity to 7.5 ds/m had not significant effect on the crude protein percentage, but with a further increase in salinity to 12 dS/m the crude protein was decreased (7.2%) significantly compared to control (Figure 2a). The forage fatty acids of Sarbishe were significantly higher (5.3%) than Birjand, which is due to the lower temperature of Sarbisheh region. The crude forage ash content in Birjand was significantly higher (5.3%) than Sarbishe (Figure 1a).With increasing the density from 10 to 20 plants per square meter the forage ash was increased (7.5%) significantly (Table 5). In Birjand, Metabolizable energy was increased (2.2 %) significantly with increasing plant density, but in Sarbishe, increasing density had not effect on this trait (Figure 5a). Irrigation water salinity application in both places and ecotypes studied was not significant effect on the metabolizable energy of camelthorn forage. Voshmgir ecotype in Birjand had significantly (11.4%) more acid detergent fiber than Korond ecotype, but the difference between these ecotypes was not significant in Sarbishe (Table 7). With increasing plant density in Birjand, the value of acid detergent fiber was decreased (7.9%) significantly but the difference between two plant densities was not significant in Sarbishe (Figure 6). At the 12 dS/m irrigation water salinity level, increasing the plant density let to a decrease (14.5%) of neutral detergent fiber, while increasing the plant density at lower irrigation water salinity levels had no effect on this trait (Table 3).ConclusionAlthough increasing the irrigation water salinity led to a significant reduction in camelthorn forage protein, but the amount of protein obtained at 12 dS/m irrigation water salinity (12.29%) was also acceptable. High irrigation water salinity levels in both ecotypes and locations did not lead to a significant reduction in forage metabolizable energy, so it is possible to produce adequate quality forage by cultivation camelthorn with saline water. Korond Ecotype was more suitable for cultivation in Birjand and Voshmgir ecotype was more suitable for cultivation in Sarbishe and produced better forage in these locations. In saline conditions, it is better to cultivate camelthorn with high plant density, because in this case, the amount of forage fiber will decrease and the forage quality will increase.
Drought stress
Farnaz Ahmadi Nouraldinvand; Raouf Seyed Sharifi; Seyed Ataollah Siadat; Razieh Khalilzadeh
Abstract
IntroductionDrought is assumed as one of the most severe abiotic stress factors limiting plant growth and crop production. Drought stress hurts plant growth and productivity which can affect biochemical and physiological responses such as changes in contribution of stem assimilates to grain, current ...
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IntroductionDrought is assumed as one of the most severe abiotic stress factors limiting plant growth and crop production. Drought stress hurts plant growth and productivity which can affect biochemical and physiological responses such as changes in contribution of stem assimilates to grain, current photosynthesis, yield and yield components. Using rhizosphere microorganisms (such as beneficial bacteria and mycorrhiza) (Dimkpa et al. 2009) and application of silicon are an alternative strategy that can improve plant performance under stress environments and, consequently, enhance plant growth through different mechanisms. Thererfore, it seems that application of nano silicon and bio-fertilizers can improve wheat yield under water limitation conditions.Materials and methodsIn order to study the effect of bio-fertilizers and foliar application of nano-silicon on the contribution of dry matter remobilization and current photosynthesis in grain yield of wheat under irrigation withholding conditions, a factorial experiment was carried out with three replications at the research farm faculty of Agriculture and Natural Resources, University of Mohaghegh Ardabili during 2018-2019. The area is 38° 15′ N latitude, 48° 15′ E longitude, and 1350 m above mean sea level. Climatically, the area is situated in the semi-arid temperate zone with a cold winter and moderate summer. Factors were included irrigation in three levels (full irrigation as control; moderate water limitation or withholding irrigation at 50% of the heading stage; severe water limitation or withholding irrigation at 50% of the booting stage) based on codes 55 and 43 of the BBCH scale; foliar application of nano silicon (foliar application with water as control, 30 and 60 mg.l-1) and bio-fertilizer (no application as control, mycorrhiza application, both application of flavobacterium and pseudomonas, both application of flavobacterium and pseudomonas with mycorrhiza). Mycorrhiza fungi (mosseae) was purchased from the Zist Fanavar Turan Corporation and soils were treated based on method of Gianinazzi et al. (2001). Psedomunas and flovobacterium were isolated from the rhizospheres of wheat by Research Institute of Soil and Water, Tehran, Iran. For inoculation, seeds were coated with gum Arabic as an adhesive and rolled into the suspension of bacteria until uniformly coated. The strains and cell densities of microorganisms used as PGPR in this experiment were 1×108 colony forming units (CFU). In this study, morphological traits, leaf area index, total biomass, dry matter remobilization from shoot and stem, contribution of stem assimilates to grain, contribution current photosynthesis in grain, yield and grain yield components of wheat were investigated. Analysis of variance and mean comparisons were performed using SAS version 9.1 computer software packages. The main effects and interactions were tested using the least significant difference (LSD) test at the 0.05 probability level.Results and discussionThe results showed that both application of mycorrhiza with flavobacterium and pseudomonas under full irrigation conditions decreased the contribution of dry matter remobilization from shoot (27.33%) and stem (17.70%) in grain yield, but increased the current photosynthesis (305.10 g.m-2) and Contribution Current photosynthesis in grain (72.66%). Also, maximum of grain yield (4593 kg.ha-1) and harvest index (38.4%) were obtained with the application of both bio-fertilizers and foliar application of 30 mg.l-1 nano-silicon under normal irrigation. Maximum leaf area index, total biomass, and yield components were obtained with the combined application of bio-fertilizers and 60 mg.L-1 nano-silicon under full irrigation conditions.ConclusionBased on the results of this study, it seems that the application of bio-fertilizers and nano-silicon can be a suitable management factor to increase grain yield of wheat under water limitation.
Drought stress
Aliyeh Alipour; Mohammad Mehdi Rahimi; Seyed Mashaallah Hosseini; Abdollah Bahrani
Abstract
IntroductionFennel (Foeniculum vulgar Mill) is one of the most important medicinal plants of the Umbelliferae family, which is cultivated mainly for the use of seeds and essential oils in various pharmaceutical, food and cosmetic industries (Norouzi Shahri et al., 2015). The medicinal plant of fennel ...
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IntroductionFennel (Foeniculum vulgar Mill) is one of the most important medicinal plants of the Umbelliferae family, which is cultivated mainly for the use of seeds and essential oils in various pharmaceutical, food and cosmetic industries (Norouzi Shahri et al., 2015). The medicinal plant of fennel in Iran is widely distributed in the regions of Khorasan, Tehran, Gorgan, Mazandaran, Kurdistan, Kerman, Gilan and Tabriz, and grows up to three meters above sea level. Plants face a variety of biological and non-biological stresses during growth. Drought stress is one of the most important abiotic stresses that reduces growth and yield in many crops and medicinal plants (Kabiri et al., 2014; Bahrani et al., 2013). Mycorrhizal fungi have several functions in the ecosystem of crops; so that it improves the physical quality of the soil, the chemical quality of the soil and the biological quality of the soil. Mycorrhiza has been reported to increase biomass, essential oil content, and ultimately essential oil function in medicinal plants (Hatami and Ghorbanpour, 2016; Ghorbanpour et al., 2014). The use of biofertilizers including Azotobacter, Azospirillium and phosphate-soluble bacteria has significant effects on the essential oil of marjoram. Growth-promoting bacteria may accumulate in the rhizosphere, root surface, or even the intracellular space of plants (Zafari et al., 2018; Bahrani et al., 2010). In general, the aim of this study was to investigate the effect of application of mycorrhiza and growth-promoting bacteria Azospirillum under drought stress on morphological traits and fennel essential oil in Zarghan and Kodian regions that have different climatic conditions.Materials and methodsAn experiment was carried out to investigated the effect of mycorrhiza (Glomus mosseae) and growth promoting bacteria (Azospirillum) in drought stress on agronomic and biochemical characteristics of Foeniculum vulgar, in 2019-2020 crop season in two regions (Kodian, Zarghan) of Shiraz, Fars province, Iran. The experiment was done as a factorial split plot in a randomized complete blocks design with three replications. Main plots were drought stress at three levels: 30% (control), 60% and 90% field capacity and sub-plots were mycorrhiza, at two levels (no inoculation, and seed inoculation with Fungal) and also Azospirillum at two levels (no inoculation and seed inoculation with bacteria).Results and discussionThe results showed that inoculation of Glomus mosseae and Azospirillum had significant effect on grain yield, biological yield, thousand seed weight, plant height, number of umbrellas per plant, essential oil yield and percentage in both regions and improved the negative effects of drought stress. The highest seed yield in both places belonged to the treatment of 30% field capacity with inoculation of mycorrhiza and Azospirillum. Mycorrhiza and Azospirillum reduced the negative effects of drought stress and increased all morphological and biochemical characteristics.ConclusionIn general, interaction of mycorrhiza and Azospirillum consumption in no drought stress can be suggested to maximize morphological and biochemical characteristics of Fennel under the same weather conditions of the study.
Physiology of crops under stress conditions
Roghayeh Beheshtizadeh; Mohammad Eghbal Ghobadi; Houshang Ghamarnia
Abstract
IntroductionStevia is a perennial herb with sweet leaves, about 300 times sweeter than sucrose and today cultivated in many parts of the world. Drought stress and nitrogen deficiency are the most important environmental stresses that limit the production of this plant and have adverse effects on plant ...
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IntroductionStevia is a perennial herb with sweet leaves, about 300 times sweeter than sucrose and today cultivated in many parts of the world. Drought stress and nitrogen deficiency are the most important environmental stresses that limit the production of this plant and have adverse effects on plant growth and development and other metabolic processes. The effect of drought stress on the plant depends on the type of plant, species, intensity, duration and growth stage of the plant. With the onset of drought decrease leaf water and stomatal conduction, and as it intensifies, loses permeability of the leaf cell membrane and damages. On the other hand, with the closure of the stomata due to lack of water is difficult and the entry of carbon dioxide into the leaves and in general, photosynthesis is reducing. Plant nutrition in drought conditions is also of special importance and proper nutrition in this situation can increase growth and stress tolerance. This element is the most important component of photosynthetic pigment proteins and has a great effect on leaf size and area.Materials and methodsTherefore, in order to investigate the effect of drought stress and nitrogen fertilizer on the growth and yield of stevia, an experiment was conducted in greenhouse of Campus of Agricultural and Natural Resources, Razi University, Kermanshah, during 2016. Factorial experiment was conducted in a Completely Randomized Design (CRD) with three replications. Treatments included drought stress at three levels (no stress, mild stress and severe stress) and nitrogen fertilizer at five levels (0, 50, 100, 150 and 200 kg.ha-1) from urea source. Irrigation time for non-stress, mid and severe stress were 50, 65 and 80%, respectively, respectively from drainage of usable moisture in the soil. The size of the Cultivation space was 50 × 50 × 50 cm (length, width and height) and they were made of cement. The irrigation system was drip irrigation. the first and second harvest were on the May 23 and September 6, 2016, respectively. Traits were examined including yield and yield components, photosynthetic pigments, relative water content (RWC), water use efficiency (WUE), soluble sugars, proline, superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT). Data were analyzed using SAS and MSTAT-C software and the means were compared using the LSD test at a probability level of 5%.Results and discussionThe results showed that the drought stress and nitrogen had a significant effect on biomass, leaf dry matter, shoot dry matter, chlorophyll a and b, carotenoids, relative water content, water use efficiency, soluble sugars, proline and enzyme Superoxide dismutase, peroxidase and catalase. The highest amount of leaf dry matter in non-stressed treatments and applying 400 kg.ha-1 N in the first and second cutting were 20.4 and 17.1 g.pl-1, respectively, and the lowest amount of leaf dry matter in severe stress treatments and applying 400 kg N ha-1 the first and second cutting were 6.81 and 5.85 g.pl-1, respectively. With increasing amounts of nitrogen increased chlorophyll a, b, a + b and carotenoids in the first and second cutting. The amount of chlorophyll a, b, a + b and carotenoids was higher in the second cutting, but in carotenoids the values were equal in both cutting. Also, with increasing drought stress decreased the RWC in the first and second cutting and in the non-drought stress in the first and second cutting were 68.4% and 70.4%, and in the severe stress were 55.0% and 58.3%, respectively. Mean comparison of the interactions (stress × nitrogen) on WUE and proline showed that in conditions non-stress and using 200 kg ha-1 nitrogen had the highest WUE. WUE in the first and second cutting were 1.94 and 0.65 g.kg-1, respectively. In this experiment, the amount of superoxide dismutase in the first and second cutting increased with increasing drought stress, but on the contrary, the amount of peroxidase in the second cutting decreased with increasing drought stress. In addition, with the increase of N, the superoxide dismutase in the first and second cutting and also the amount of peroxidase increased in the second cutting.ConclusionIn general, it can be concluded that stevia production in the second year has a good yield under non-drought stress. In addition, the use of nitrogen in conditions non-stress increased leaf yield. Leaf yield under mid stress with nitrogen application was not very significant. Under drought stress reduced leaf yield and was more severely with nitrogen utilization. Stevia is a summer plant with high water uses. It is recommended to pay attention to the amount of water available in summer and usually have a shorter irrigation cycle than other summer crops in the region, which is economically viable.
Salinity stress
Vahid Atlassi Pak; Omid Bahmani; Mahsa Asadbegi
Abstract
IntroductionSalinity impacts on crop production is further increasing as the global demand for food means agriculture extends into naturally salt-affected lands. Chlorophyll retention and the low sodium traits were associated with salt tolerance in wheat and barley under salinity conditions. Saline soils ...
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IntroductionSalinity impacts on crop production is further increasing as the global demand for food means agriculture extends into naturally salt-affected lands. Chlorophyll retention and the low sodium traits were associated with salt tolerance in wheat and barley under salinity conditions. Saline soils limit plant growth due to osmotic stress, ionic toxicity, and a reduced ability to take up essential minerals. Barley and wheat have different salt tolerances capacities and are grown as major grain crops in both saline and non-saline soils. The net sodium uptake for a plant growing in 150mM NaCl with perfect osmotic adjustment is similar to actual rates measured for wheat and barley. Our hypothesis is that salinity reduces the growth of wheat more than barley by reducing chlorophyll content. The aims of this study were to analyse the effects of salinity on the growth and yield of barley and wheat cultivars to explore the links between the sodium accumulation and chlorophyll content.Materials and methodsTow bread wheat cultivars differing in salt tolerance (Arg and Tajan) and a barley cultivar (Nik) were used to assess the change in the chlorophyll content and sodium accumulation over time under saline conditions. Two levels of NaCl (0 and 150 mM NaCl) were imposed as the salinity treatments when the leaf 4 was fully expanded. At 21 days after salt treatment plants were harvested and shoot and root dry weight, root length and sodium root were measured. Sodium accumulation rates and chlorophyll content examined between days 14 and 42 after salt added. Na+ and K+ flag leaf were measured in days 49 after salt treatment started.Results and discussionResults showed that the rate of sodium accumulation initially was the same for both wheat cultivars in leaf. After 30 days of salinity, the rate of sodium accumulation rose in Arg compared with Tajan. In Nik barley cultivar, shoot sodium concentration was higher than bread whit cultivars. Salinity caused degradation in chlorophyll content in both bread wheat cultivars and at the determination of this experiment Tajan had lower chlorophyll content than Arg cultivar. Nik barley cultivar showed much longer chlorophyll retention than tow bread wheat cultivars. Salinity decrease K+ flag leaf, K+/Na+ flag leaf, shoot and root dry weight, seminal root length, yield and increase Na+ flag leaf and Na+ roots compared to control. Flag leaf K+/Na+ ratio was higher in salt tolerance cultivar (Arg) compared to Tajan and Nik, despite the similar roots sodium concentration. Flag leaf Na+ concentration was the same in tow wheat cultivars and barley under salinity stress and there was no relationship between Na+ exclusion and salt tolerance in cultivars in our experiment. Yield loss of 35 percentages was found in wheat cultivars on average and in barley did not observed remarkable decrease in seed yield. There was may be no beneficial effect of the low Na+ trait at 150 mM NaCl (high salinity level) in all cultivars. Root length reduction in cultivars was due to osmotic stress of salt solution out of the roots. A significant correlation between shoot dry weight and sodium flag leaf showed that sodium concentration in leaf can be used as an index for evaluating salt tolerance.ConclusionGiven the effect of salinity on shoot growth, it seems that other factors may have influenced net carbon gain before any reduction in the concentration of chlorophyll. It implies that osmotic and tissue tolerance in bread wheat and barley contributed to the salt tolerance in tolerant cultivars and preferential sodium accumulation and maintains in roots and old leave relative to young leaves can caused an increase in salt tolerant. The low shoot sodium concentration was not associated with chlorophyll content in wheat cultivars.
Drought stress
Mahboobeh Yazdi; AbdolReza Bagheri; Nasrin Moshtaghi; Ahmad Sharifi
Abstract
IntroductionPlants are exposed to various environmental stresses during growth and development under natural and agricultural conditions. Drought is one of the most severe abiotic stresses that greatly affects plant yield. Metabolic changes under stress cause the morphological and physiological changes ...
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IntroductionPlants are exposed to various environmental stresses during growth and development under natural and agricultural conditions. Drought is one of the most severe abiotic stresses that greatly affects plant yield. Metabolic changes under stress cause the morphological and physiological changes in the plant which may eventually lead to reduced yield. Barley is one of the most important cereals which a large part of the human population in many parts of the world are dependent on it as a source of food and animal feed.Materials and methodsIn order to investigate the effects of drought stress on some morphological and physiological traits in barley as one of the most important crop, this experiment was carried out in the greenhouse of the agriculture faculty, Ferdowsi University of Mashhad in 2019 in a factorial based on a randomized complete block design with three replications. Experimental factors were included: different levels of drought stress including 100% of field capacity (control or no stress), 80, 60 and 40% of field capacity and two barley cultivars containing semi-sensitive (Fajr30) and drought tolerant (Dasht). First, the seeds of both cultivars were planted in trays filled with coco peat, perlite and sand, and after two weeks, the seedlings were transferred to pots filled with garden soil. The pots were watered daily and after one month (4 to 6 leaf stage) until the end of the growing season, they were subjected to drought stress treatments. During the vegetative stage, morphological traits such as plant height (from crown to end of plant), stem diameter, number of leaves, number of tillers, leaf area and number of stomata below and above the leaf were examined using common methods. Physiological traits including proline, soluble sugars, photosynthetic pigments and antioxidant enzymes (catalase and peroxidase) were also measured. Analysis of variance was performed using JMP statistical software version 8 and the mean of treatments was compared using LSD test at the level of 5%.Results and discussionThe results of this experiment showed that the effect of cultivar and drought stress were significant for many of the studied traits. The highest plant height, stem diameter, number of leaves and tillers and leaf area index were observed in plants without stress (100% FC), which was significant compared to other stress level. Also, the comparison of the two cultivars showed that Dasht, as a drought tolerant cultivar, has more leaves and tillers but less leaf area and stomata than the semi-sensitive cultivar Fajr30. In other words, the tolerant cultivar produces more leaves but smaller under stress condition which finally reduces the leaf area compared to the sensitive cultivar. This can be a good solution for drought resistance through reduce evaporation from the leaf surface as well as shading. In addition, osmotic regulators such as proline and soluble sugars and the activity of antioxidant enzymes including catalase and peroxidase increased under drought stress and it was higher in tolerant cultivar. In fact, it seems that tolerant cultivar can tolerate drought stress through activating their immune system by producing osmoprotectant and increasing the activity of antioxidant enzymes.ConclusionIn general, results showed that proline, soluble sugars and antioxidant enzymes play a role in the mechanism of stress tolerance and their metabolism is affected by drought stress. The results of this experiment suggest that the accumulation of these osmoprotectans and morphological changes can be part of the drought resistance mechanisms in the drought tolerant genotype of barley, which can ultimately be used in breeding programs to improve drought tolerance. In general, the results of this experiment showed that both barley cultivars responded to drought stress, but Dasht cultivar showed more tolerance in these conditions.
Drought stress
Hana Aboodeh; abdelmehdi bakhshandeh; Mohammad Reza Moradi Telavat; Seyed Ataollah Siadat; Seyed Amir Moosavi
Abstract
IntroductionThe response of plants to drought stress conditions is related to the severity of stress and its growth stage. The amount of nitrogen and protein in oilseeds is related to the optimal storage of soil moisture. Under drought stress conditions, by reducing the grain size, oil content and protein ...
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IntroductionThe response of plants to drought stress conditions is related to the severity of stress and its growth stage. The amount of nitrogen and protein in oilseeds is related to the optimal storage of soil moisture. Under drought stress conditions, by reducing the grain size, oil content and protein content, it fills a large volume of grain space compared to non-stress conditions. One of the serious problems in rapeseed production is the problem of water shortage in the reproductive period. In order to solve this problem, relying on genetic potential and introducing genotypes and cultivars tolerant to drought stress is one of the practical ways.Materials and methodsIn order to evaluation of the effect of cut-off stress on protein and seed oil content of spring rapeseed genotypes a split plot experiment was conducted based on the randomized complete block design with three replications at the research farm of department of plant production and genetics, Agricultural Sciences and Natural Resources University of Khuzestan, Iran during 2020-2021. Main plots included three irrigation treatment: control (without interruption of irrigation), interruption of irrigation in the beginning of flowering stage (phenology code 60) to the formation of 50% pods (phenology code 75) and interruption of irrigation in the stage of formation of pods until harvest (Phenology code 99) in the main plots and the genotypes (Long pod, Aram, RGS 003, Jankom, Solar, Hayola 4815, Mahtab, Julius, Agamax and Sala) were arranged in sub-plots with respect to irrigation treatments. The amount of seed oil was determined by purim method. Oil yield was obtained by multiplying the percentage of oil in grain yield by kilograms per hectare. Grain nitrogen content was calculated by Kjeldal apparatus. Protein yield was obtained by multiplying the percentage of protein in grain yield by kilograms per hectare.Results and discussionThe results of this study showed that the interaction effect of cutoff stress and genotype on all traits except grain protein yield was significant. The highest oil percentage and seed oil yield were observed under normal conditions by Hayola 4815, Langpad and Solar genotypes. The highest percentage of seed oil in both applied stresses was assigned to Hayola 4815, Langopad and Mahtab genotypes. Regarding grain protein content and nitrogen content, the highest amount of mentioned traits was obtained under drought stress conditions and lazy genotypes, Jankom, RGS003 and Hayola 4815. In general, under the conditions of cessation of irrigation stress, the amount of grain protein increased, however, the oil content was decreasing and a significant negative correlation was observed under normal conditions and stress between the two traits. Due to the higher values of MP, GMP, HM, STI and YI indices in terms of seed oil yield, compared to other genotypes under drought stress conditions were suggested as the superior treatment.ConclusionUnder drought stress, grain nitrogen content and increase while oil grain decreases, in fact, the amount of nitrogen, oil and seed oil under irrigation stress conditions have a negative and significant correlation.
Drought stress
Pouya Sohrabi Noor; Mohammad Ali Aboutalebian; Javad Hamzei
Abstract
IntroductionSoybean (Glycine max L.) is one of the most important oilseeds in the world due to its 18 to 22% seed oil and high protein content (36-38%). Meanwhile drought stress is one of the important factor limiting its growth and yield. Drought stress limits root growth and reduces the mobility of ...
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IntroductionSoybean (Glycine max L.) is one of the most important oilseeds in the world due to its 18 to 22% seed oil and high protein content (36-38%). Meanwhile drought stress is one of the important factor limiting its growth and yield. Drought stress limits root growth and reduces the mobility of important micro-nutrients especially zinc in the soil. Application of zinc sulfate fertilizer increases physiological growth parameters, grain yield and water use efficiency in soybeans. Also mycorrhizal colonization in plants increases growth, improves yield, and increases the plants resistance to drought stress. This study aims to evaluate the effect of mycorrhiza and zinc sulfate fertilizer application method on some soybean growth physiological indices and its water use efficiency under soil moisture deficit stress.Materials and methodsThe experiment was performed as a factorial experiment in the form of randomized complete blocks with three replications. First factor was moisture stress at three levels of no-stress, mild stress and severe stress (irrigation after 60, 90 and 120 mm evaporation from Class A pan, respectively). Second factor was arbuscular mycorrhiza (Funneliformis mosseae) in two levels of application and no-application and third factor was the application method of zinc sulfate fertilizer in three levels of no-application, soil application and foliar feeding. To evaluate the response of growth indices of soybean, plant samples were prepared during the growing season and their leaf area and dry matter were measured. Water use efficiency was also obtained from the ratio of grain yield to the volume of water consumed. During flowering stage, the percentage of mycorrhiza colonization was measured and grain yield was obtained by harvesting two square meters from each plot.Results and discussionIn this experiment, severe moisture stress shortened the growth period of soybeans. The results showed that at all levels of moisture stress, inoculation with mycorrhiza increased leaf area index, crop growth rate, water use efficiency and grain yield. Application of mycorrhiza and foliar feeding of zinc sulfate increased maximum leaf area index, maximum crop growth rate and water use efficiency by 69, 98 and 112%, respectively. In the absence of mycorrhiza, soil application of zinc sulfate had no effect on maximum leaf area index and maximum crop growth rate, but the use of mycorrhiza led to a 15 and 20% increase in these indices by soil application of zinc sulfate compared to no zinc sulfate use. Severe and moderate moisture stresses in no-application of mycorrhiza and no zinc sulfate reduced the total dry matter by 47.22 and 63.04%, respectively, but the application of mycorrhiza in these treatments has reduced the severity of these effects and led to increase of 111.20% in total dry matter. The highest colonization of mycorrhiza occured in moderate moisture stress (65.33%). Soil application of zinc sulfate reduced the colonization of mycorrhiza even compared to the no-application of zinc sulfate fertilizer. In this study, the highest percentages of mycorrhizal colonization occured in moderate moisture stress and foliar application of zinc sulfate by 64 and 59%, respectively. Foliar feeding of zinc sulfate compared to no-zinc sulfate, under severe moisture stress increased grain yield by 68% (1100 kg ha-1). No-application of mycorrhiza led to no difference between soil use and no-application of zinc sulfate in soybean yield. Mycorrhiza in no-moisture stress, moderate stress and severe stress increased water use efficiency by 80.49, 183.33, 275% respectively, compared to no-application of mycorrhiza.ConclusionAccording to the results, foliar feeding of zinc sulfate is more efficient than soil application of zinc sulfate, but this efficiency decreases during moisture stress. Application of mycorrhiza in addition to reducing the effects of moisture stress can increase the efficiency of zinc sulfate fertilizer especially under foliar feeding conditions.
Salinity stress
Masoumeh Salehi; Farhad Dehghany
Abstract
IntroductionQuinoa (Chenopodium quinoa Willd.) is a beneficial plant with high nutritional value with high tolerance to salinity and drought stress. Most of the experiments performed on the study of quinoa salinity stress tolerance in pot and greenhouse conditions were not comparable to the results of ...
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IntroductionQuinoa (Chenopodium quinoa Willd.) is a beneficial plant with high nutritional value with high tolerance to salinity and drought stress. Most of the experiments performed on the study of quinoa salinity stress tolerance in pot and greenhouse conditions were not comparable to the results of cereal experiment such as wheat and barley performed in field conditions. The purpose of this experiment is to determine the threshold value of quinoa to salinity stress under field conditions.Materials and methodsAn experiment was performed as a split plot in a randomized complete block design with three replications on August 7, 2017 at Sadough Salinity Research Station of Yazd National Salinity Research Center. Experimental treatments including five quinoa genotypes including three quinoa lines (NSRCQE, NSRCQB, NSRCQC) with Titicaca and Sadough cultivars as subplots and irrigation water salinity at five levels of 2, 5, 10, 15 and 17 dS m-1 in the main plot. During the growing season, soil samples were taken from the plant root development area. Seed yield and yield components were measured. The percentage of saponin, seed vigor, 1000-seed weight and grain size were also measured.Results and discussionThe results of analysis of variance of the measured traits showed that the effect of salinity stress on plant height, 1000-seed weight and grain yield was significant at the level of 1%. The effect of salinity stress on grain size was not significant. Differences between genotypes in terms of plant height, grain yield, 1000-seed weight, biomass and grain size were significant at the level of 1% and panicle length and number of lateral panicles at the level of 5%. The interaction effect of genotype and salinity on biomass was not significant at 5% level and on other traits was not significant. The percentage of saponin between genotypes was significant at the level of 5%. The interaction effect of salinity and genotype on biomass and saponin percentage was significant at 5% level. The percentage of grain saponin increased significantly with increasing salinity in NSRCQB genotype and was not affected by salinity stress in other genotypes. Biomass of all genotypes except Titicaca was not significantly different up to salinity of 10 dS m-1. The highest biomass production in non-saline conditions was related to NSERCQE and Sadough cultivar and These two genotypes had the lowest decrease in biomass production with increasing salinity. Seed viability was not affected by salinity increase except in NSRCQB genotype seed vigour decreased by 15%. The lowest 1000-seed weight in non-saline conditions was related to NSRCQB genotype and the trend of 1000-seed weight loss with increasing salinity was similar to all genotypes and decreased by an average of 16%. The results of mean comparison showed that the highest yield at all salinity levels was observed in Sadough cultivar. Based on the results of the fitted linear equation, changes in quinoa seed yield to salinity showed that the salinity tolerance thresholds of quinoa genotypes were 4.3, 8.7, 4.1, 4.8, and 6.8 dS m-1 of electrical conductivity of saturated soil extracts, respectively. The soil and slope of the line were 3.5, 2.4, 0.1, 0.7 and 0.9%. Fifty percent reduction in wheat yield of Kavir and barley cultivars of Marvdasht cultivar has been reported at 15 and 20 dS m-1 of soil salinity, while Quinoa Sadough cultivar at 24 dS m-1 of electrical conductivity of soil saturated extract was 80% seed yield in non-saline conditions. Sadaogh cultivar not only have suitable agronomic characteristics and high production potential in saline conditions, but also has a higher salinity tolerance.ConclusionQuinoa has a higher tolerance to salinity stress than wheat and barley and can be a promising plant for using saline water and soil resources that are not economically viable for crop production. There is also a good variety among quinoa genotypes to select for using saline water.AcknowledgmentsThis project has been done with the financial support of the Researchers Support Fund and the Agricultural Education and Extension Research Organization (AREEO).
Breeding plants for stress conditions
Saeed Bagherikia; Habiballah Soughi; Manoochehr Khodarahmi
Abstract
IntroductionWheat performance is always affected by climate change and environmental stresses such as drought stress. Development of high-yielding cultivars requires genetic diversity. Awareness about heritability of traits can be helpful in determining the appropriate breeding strategy for any environmental ...
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IntroductionWheat performance is always affected by climate change and environmental stresses such as drought stress. Development of high-yielding cultivars requires genetic diversity. Awareness about heritability of traits can be helpful in determining the appropriate breeding strategy for any environmental conditions. By progeny trial after a diallel crossing, the function of genes and inheritance of quantitative traits can be estimated. This increases the ability to select parental lines, to participate in crosses, and determines the management of generations in the segregating populations. Materials and methodsIn order to understand the genetic structure of grain yield and some morphological traits of bread wheat under normal and drought stress conditions, eight bread wheat cultivars including Star; Tirgan; Ehsan; Shirodi; Bam; Tajan, Yang and Akbari were planted in the crossing block and direct crosses were performed among the eight cultivars to produce F1 generation. This research carries out in Gorgan agricultural research station in 2020-2021 cropping season, under normal and drought stress conditions. The progenies of the crosses with their parents were evaluated based on a randomized complete block design (RCBD) with three replications. Imposing stress by terminating irrigation was initiated at the Zadoks 60 (full heading emergence) stage. Results and discussionCombined analysis of variance under normal and drought stress conditions showed that the simple effects of genotype and environment were statistically significant in all traits. Also, the interaction effects of genotype×environment was statistically significant for grain yield, biological yield and 100-kernel weight. In fact, for these traits the response of genotypes was different under normal and stress conditions. Analysis of variance of Griffing's diallel method showed a statistically significant difference between genotypes in all studied traits. Therefore, among the progenies of the crosses it is possible to select superior genotypes. In biological yield and grain yield under both normal and drought stress conditions, Tirgan cultivar had the highest general combining ability, while Star cultivar showed the lowest general combining ability. Tirgan cultivar can be used to increase grain yield and biological yield under both conditions. In plant height, peduncle length and harvest index, Tajan×Yang, Ehsan×Shirodi and Bam×Yang crosses had the maximum specific combining ability, respectively. In other traits, in each condition, an individual cross had the highest specific combining ability. Under normal conditions, Tajan×Akbari cross had the highest specific combining ability in grain yield. Under drought stress conditions, Bam×Akbari cross had the highest specific combining ability in biological yield and grain yield, it simultaneously had a high specific combinability in 100-grain weight, harvest index and number of grains per spike. Therefore, Bam×Akbari cross was determined as the best cross in genetic improvement of desirable agronomic traits with high specific combining ability in yield and yield components, under drought stress conditions. The ratio of additive variance from genetic variance for plant height and peduncle length was greater than dominance variance. Subsequently, the highest narrow-sense heritability in both normal and drought stress conditions was related to plant height and peduncle length. In both normal and drought stress conditions, the highest degree of dominance was related to harvest index traits and number of grains per spike, respectively. Therefore, in these traits the lowest narrow-sense heritability, the lowest Baker's genetic ratio and the highest ratio of dominance variance from genetic variance were observed in both normal and drought stress conditions. In grain yield, a high ratio of dominance variance from genetic variance was assigned under normal (84%) and drought stress (88%) conditions, hence low narrow-sense heritability was observed under normal (8%) and drought stress (5%) conditions. In general, in grain yield, biological yield and 100-kernel weight, narrow-sense heritability was lower under drought stress conditions, compared to normal conditions, which indicates a greater ratio of non-additive effects under drought stress conditions. ConclusionThe results of this study showed that under both conditions, Tirgan cultivar had the highest general combining ability in grain yield and biological yield. Tajan×Akbari and Bam×Akbari crosses were determined as the best cross in genetic improvement of desirable agronomic traits with high specific combining ability in yield and yield components, under normal and drought stress conditions, respectively. In grain yield, biological yield and 100-kernel weight, narrow-sense heritability was lower under drought stress conditions, compared to normal conditions. Based our results under both conditions in the progenies of the crosses, genetic improvement can be done in plant height and peduncle length in the initial generations, but for other traits including grain yield and its components, selection should be postponed to more advanced generations.
Physiology of crops under stress conditions
Elnaz Sattarzadeh; Mehrdad Yarnia; Ebrahim Khalilvand Behrooznia; Bahram Mirshekari; Varahram Rashidi
Abstract
IntroductionLavender (Lavandula officinalis L.) belonging to the Lamiaceae family is a plant with economic, medicinal and ornamental value. Its essential oil is used as a raw material for many industries, including perfumery, cosmetics, and pharmaceutical industries. Drought stress as a limiting factor ...
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IntroductionLavender (Lavandula officinalis L.) belonging to the Lamiaceae family is a plant with economic, medicinal and ornamental value. Its essential oil is used as a raw material for many industries, including perfumery, cosmetics, and pharmaceutical industries. Drought stress as a limiting factor reduces growth and productivity in plants. This issue is especially important in arid and semi-arid regions of the world such as Iran. One of the basic solutions to adjust or reduce the effect of water stress in agricultural plants is the use of different types of biological fertilizers. Also, its low diffusion speed in the soil can play an important role in the lack of its ions in the solution in the soil of the root development area. In most agricultural systems, due to the low mobility of phosphorus in the soil, absorption by the plant is low. In order to investigate the effect of biofertilizers and phosphorus on reducing the effects of irrigation deficiency in lavender, an experiment was conducted in the form of split plots in a randomized complete block design with 3 replications at the Research Station of the Faculty of Agriculture, Islamic Azad University of Tabriz in 2019-2020.Materials and methodsExperimental factors including irrigation levels (irrigation after 60, 90 and 120 mm from Class A evaporation pan) as the main factor and inoculation with biofertilizer including four levels (inoculation with Thiobacillus, Pseudomonas and Thiobacillus + Pseudomonas and no inoculation As control) and phosphorus fertilizer levels at two levels (0 and 50 kg ha-1) as a secondary factor. The studied traits included leaf dry weight, flower dry weight, cell membrane leakage rate, relative leaf water content, soluble sugars and proline content, catalase and superoxide dismutase enzymes and peroxidase and MDA. To measure the activity of antioxidant enzymes, leaf samples kept at -80 degrees Celsius were used. The activity of catalase was measured using the method described by (Aebi, 1984; Ezhilmathi, 2007). The measurement of superoxide dismutase (SOD) enzyme was calculated according to the method (Giannopolitis and Ries, 1977) based on enzyme unit per milligram per body weight. The determination of malondialdehyde (MDA) was based on Aston and Sidney's method (Aston and Sidney, 1987). Proline content in the youngest leaf was also determined by the method of Bates et al. (1973). SAS version 8 software was used to analyze the variance of the data, MSTATC version 2 software was used to compare the averages, and Excel software was used to draw the figures.Results and discussionThe results showed that at all levels of irrigation, phosphorus consumption and inoculation with integrated biofertilizers increased the dry weight of flowers compared to the control. Irrigation after 60 mm of evaporation from the pan with the application of 50 kg of phosphorus per hectare and application of Thiobacillus + Pseudomonas obtained the highest dry weight of flowers (833.3 g ha-1). The highest leaf dry weight was proline, catalase, peroxidase, superoxide dismutase and malondialdehyde at 60 ml of evaporation with 50 kg ha-1 application and application of Thiobacillus + Pseudomonas. The results of this study also showed that the effects of interaction between irrigation, phosphorus and biofertilizer levels on cell membrane leakage, leaf dry weight and relative leaf water content were not significant.ConclusionBased on the results of this experiment, it can be said that in water stress conditions, the use of biological fertilizers combined with the use of phosphorus fertilizers can greatly reduce the incidence of malnutrition in lavender medicinal plant. The accumulation of soluble sugars, proline and the increase in the activity of antioxidant enzymes in this plant in the face of drought stress can be considered as drought tolerance mechanisms. The combined use of Thiobacillus and Pseudomonas bacteria had better results than the use of these bacteria alone; Therefore, if the intensity of water deficit stress in this plant is not high, the effects of water deficit stress can be reduced by using biological fertilizers and phosphorus fertilizer.
