Biotechnology and environmental stresses
Maryam Lotfi Sarabi; Reza Fotovat; Ehsan Mohseni Fard
Abstract
IntroductionThe yield of wheat (Triticum aestivum L.), is greatly reduced under environmental stress and decreased temperatures. Therefore, adaptation mechanisms and cold resistance are crucial in this plant. Vernalization is known as one of the essential mechanisms for grain adaptation to environmental ...
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IntroductionThe yield of wheat (Triticum aestivum L.), is greatly reduced under environmental stress and decreased temperatures. Therefore, adaptation mechanisms and cold resistance are crucial in this plant. Vernalization is known as one of the essential mechanisms for grain adaptation to environmental conditions, whereby the plant can accelerate the flowering process or flower after a long cold period. Vernalization also plays a significant role in the acquisition of cold resistance in wheat plants. When exposed to low temperatures, certain genes related to vernalization are activated, leading to changes in the plant's physiology and allowing it to a better cold stress tolerance. This process involves complex regulatory mechanisms depending on the cultivar and environmental conditions. Understanding the molecular basis of vernalization and the genes involved in cold resistance could assist in developing new strategies to improve wheat productivity in adverse environments.Materials and methodsIn this research, we investigated the expression of three genes, NAC, ERF, and TCP, related to vernalization in two wheat cultivars named Baz and NorthStar, which known as spring and winter cultivars, respectively. The plant samples were preserved in growth racks and applied for vernalization treatment after the tillering stage. RNA extraction was performed at this stage. Real-Time PCR technique was then utilized to analyze the gene expression. To better understanding the function of these genes in response to cold stress, the promoter of the three studied genes was analyzed by screening 500 nucleotides upstream of the wheat TSS. The vernalization treatment was applied at two levels of 14 and 21 days and compared to the control plants under 4°C.Results and discussionThe results showed that the expression of all three genes (TCP, NAC, and ERF) decreased under the vernalization treatment. However, the expression of the TCP and NAC genes increased after 14 and 21 days of treatment in the NorthStar and Baz varieties, respectively. In general, the decreased level of expression was shown by increasing in the number of vernalization days. Notably, the expression of the ERF gene reduced in both tested varieties with the increased number of vernalization days. This trend was also observed in the expression of the NAC gene. However, the vice versa was observed for NAC gene in the Baz variety by an increased expression. In the Baz variety, the expression rate of the TCP gene decreased with an increase in the number of vernalization days, whereas in the NorthStar variety, the gene expression increased and then decreased after 14 and 21 days of treatment. Based on the abundance and diversity of the identified elements resulting from the analysis of the promoters of the studied genes, 28 types of regulatory elements were identified, many of which are binding sites for transcription factors responding to biotic and abiotic stresses Top of Form.ConclusionDespite the similarity of the pattern of expression changes of all three genes in the two investigated cultivars, the intensity of the changes in the two cultivars was not same, which could be due to different reactions to cold stress. The results show the complexity of gene expression regulation in wheat vernalization. Additionally, the multiplicity of stress-responsive transcription factor binding sites in the promoter region of these genes could be a justification for the complexity of regulating their expression during vernalization and response to cold stress.
Physiology of crops under stress conditions
Fatemeh Hedayati; Nasibeh Pourghasemian; Mehdi Naghizadeh; Roohola Moradi
Abstract
IntroductionMarigold (Calendula officinalis L.) is an annual plant in the Asteraceae family that has been cultivated for ornamental purposes for many years. However, the plant's medicinal properties have also been identified and it is now commonly used for medicinal purposes. The most abundant compounds ...
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IntroductionMarigold (Calendula officinalis L.) is an annual plant in the Asteraceae family that has been cultivated for ornamental purposes for many years. However, the plant's medicinal properties have also been identified and it is now commonly used for medicinal purposes. The most abundant compounds found in marigold are phenolic compounds, including flavonoids and phenolic acids, as well as saponins. The biosynthesis of secondary metabolites in plants is heavily influenced by environmental factors, which are known to significantly affect both the quantity and composition of these compounds. Environmental factors can be present in varying conditions, sometimes in levels that are optimal for plant growth and sometimes in levels that are stressful and can negatively impact plant growth and development. A substantial portion of the earth's arable land, approximately 6%, is affected by salinity, which can lead to oxidative stress in plants. Although, zinc is an essential micronutrient required for plant growth, excessive levels of this element can be toxic and result in oxidative stress, ultimately leading to plant death. There are various methods to mitigate the impacts of metal toxicity and salinity stress on plants, and one effective approach is the use of biochar as a soil amendment. Beeswax waste has recently been identified as an organic material, and studies have shown that it is a nutrient-rich substance that can be applied as a fertilizer. Given the dual importance of marigold as both a medicinal and ornamental plant, the present study aimed to explore the potential of beeswax waste biochar in mitigating the negative impact of salinity and zinc stress on this plant species. Furthermore, the study aimed to investigate the effects of varying concentrations of zinc, ranging from low to high levels, on the growth and development of marigold. The study also examined the synergistic effects of zinc and salinity on marigold growth, as well as the role of both high and low concentrations of zinc under saline conditions and in the presence of different biochar levels.Materials and methodsTo investigate the impact of beeswax waste biochar application on marigold growth under salinity and zinc stress, a factorial experiment was conducted using a completely randomized design with three replications. The experimental factors included two levels of salinity stress (control EC=1 dsm -1; salt stress with EC=6 dsm-1), four levels of zinc element (control, 300, 1500, and 3000 mgkg-1 soil), and three levels of beeswax waste biochar (control, 1.5%, and 3% ww-1). Biochemical traits, including photosynthetic pigments (chlorophyll a, b, and total), phenol, flavonoid, anthocyanin, catalase, and ascorbate peroxidase enzymes, were measured three months after planting. Yield traits, such as biomass and flower dry weight, were measured approximately four months after planting, when the plants exhibited signs of decline.Results and discussionThe results of the experiment revealed that salinity and zinc stress significantly reduced the biomass, flower and root dry weight, and height of marigold plants compared to the non-stress condition. Among the treatments, the highest amount of biomass and dry weight of flowers were observed in the control treatment (without salinity stress) with 300 ppm of zinc and 1.5% biochar, which were 9.83 gr and 1.59 gr, respectively. Conversely, the lowest values were observed in the treatment with 6 dSm-1 salinity and 1500 ppm of zinc concentration without biochar, which were 1.8 gr and 0.27 gr, respectively. Although the amount of photosynthetic pigments and secondary metabolites, such as phenolic compounds, flavonoids, and anthocyanins, decreased compared to the non-stress condition, the activity of catalase and ascorbate peroxidase enzymes increased under salinity and zinc stress compared to the control treatment. Furthermore, the application of biochar in plants under salinity and zinc stress conditions increased vegetative traits, improved photosynthetic pigments, secondary metabolites, and antioxidant enzymes compared to the condition of not applying biochar.ConclusionLow zinc concentration had a positive impact on marigold growth, but concentrations higher than 300 ppm resulted in toxicity and stress. Salinity and zinc stress caused a decrease in growth characteristics, photosynthetic pigments, and secondary metabolites. Remarkably, the application of biochar, even in the presence of salt stress with 300 ppm zinc concentration, improved the growth and biochemical characteristics of marigolds.
Drought stress
Sepideh Tarrah; Hamid Dehghanzadeh; Mojtaba Jafarzadeh Kenarsary
Abstract
IntroductionDrought stress, as the most important abiotic stress, plays an important role in reducing crop production. Wheat is the most important crop in Iran. In arid and semi-arid regions, it is very important to obtain cultivars that have more tolerance to water limitation and water deficit irrigation. ...
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IntroductionDrought stress, as the most important abiotic stress, plays an important role in reducing crop production. Wheat is the most important crop in Iran. In arid and semi-arid regions, it is very important to obtain cultivars that have more tolerance to water limitation and water deficit irrigation. By achieving such cultivars and determining their tolerance to low irrigation, it is possible to prevent the loss of water resources to a large extent and at the same time obtain a suitable yield in the conditions of water limitation. Although genetic improvements in grain yield under favorable and stress conditions have been clearly seen over the past few decades, the search for genetic differences and more effective selection criteria, especially under stress conditions, should be continued. Investigating the effects of different irrigation regimes in different phonological stages on wheat grain yield and introducing the best irrigation regime for this crop in the dry weather conditions of Aran Va Bidgol region are the main aims of this research.Materials and methodsIn order to evaluate the effect of drought stress on yield, yield components and some physiological traits of three bread wheat cultivars, the experiment was conducted during 2013-2014, in Aran va Bidgol province. A split factorial experiment based on randomized complete block design with three replications was used. The main plots considered irrigation regimes (irrigation after 60, 95 and 130 mm cumulative evaporation from class A evaporation pan), and sub-plots considered two growth stage (from elongation to heading and from heading to ripening) and three wheat cultivars (Sepahan, Roshan Back-Cross and Kavir) as factorial. Sowing was done by hand with a density of 400 seeds per square meter. Weeds were controlled by mechanical method. In the stages of elongation, heading, pollination and grain filling, the amount of water consumed in each irrigation was estimated for the main plots and was introduced to the plots during irrigation. The SPSS software was used to analyze the data. If the effect of the experimental factor was significant, the LSD test was used at the 5% probability level to compare the means.Results and discussionResults showed that delay in irrigation from 60 to 130 mm cumulative pan evaporation significantly reduced plant height, number tiller, yield and yield components, harvest index, relative water content, leaf chlorophyll content and increased the wax of coticule and water use efficiency. Irrigation after 90 and 130 mm cumulative evaporation from class A evaporation pan decreased grain yield 12 and 41.8 percent compared controlled, respectively. The reduction of water consumption in mild and severe stress treatments compared to the control treatment was 20 and 43%, respectively. Applying drought stress from the heading to ripening, led to a greater decrease in grain yield and harvest index compared to applying stress from the elongation stage to heading. The Kavir, Sepahan and Back-cross Roshan cultivars had the highest to the lowest grain yield, with 3941, 3868 and 3757 kg. ha-1, respectively. The Kavir cultivar had low plant height, high the wax of coticule (both control and stress conditions), resume high relative water content (both control and stress conditions), high leaf chlorophyll content, harvest index and water use efficiency, caused to higher grain yield.ConclusionIt was concluded that by irrigation the Kavir wheat cultivar after 95 mm cumulative pan evaporation from elongation to heading, water could be saved by 20% with 12% loss in grain yield under these conditions.
Breeding plants for stress conditions
Solmaz Azizi; Nasser Zare; Parisa Sheikhzadeh; Javanshir Azizi; Rahmatollah Karimizadeh
Abstract
IntroductionDrought stress is one of the most important abiotic factors that can limit plant growth and yield. The response of plants to water limitation has been evaluated based on genetic, biochemical, and morpho-physiological traits. Plants are constantly affected by drought stress and re-irrigation. ...
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IntroductionDrought stress is one of the most important abiotic factors that can limit plant growth and yield. The response of plants to water limitation has been evaluated based on genetic, biochemical, and morpho-physiological traits. Plants are constantly affected by drought stress and re-irrigation. Therefore, rapid and efficient recovery from water deficit stress may be one of the key determinants of drought adaptation in plants. The aim of this research was the evaluation of drought stress tolerance and recovery in lentil cultivars after stress conditions.Materials and methodsIn order to evaluate the response of lentil cultivars to drought stress and re-irrigation, a factorial split-plot experiment based on a randomized complete block design with three replications was conducted in the greenhouse. Drought stress was applied at the flowering stage. The factors include 4 lentil cultivars (Namin landrace and Sepehr, Gachsaran, and Kimiya cultivars), drought stress (control (irrigation at 80% FC), medium stress (irrigation at 55% FC) and severe stress (irrigation at 30% FC)) and 3 sampling times (three and six days after drought and recovery (two days after re-irrigation)). All the plants were allowed to grow until the flowering stage (50 days after sowing) under well-watered conditions (80% FC (field capacity) of soil). Afterward, the plants were randomly assigned to three different groups and were exposed to different irrigation regimes including the control (well-watered and maintained at 80% FC), medium stress (watered and maintained at 55% FC), and severe drought stress (watered and maintained at 30% FC). The moisture content of the soil was controlled and maintained within a defined range using the weight method. Stress conditions were kept until the crop maturity and harvesting stage. The leaf samples from 5 seedlings of each pod were collected at 3 and 6 days after drought stress exposure, and two days after re-irrigation and used for physiological and biochemical analysis. The samples immediately were frozen in liquid nitrogen and stored at −80°C until analysis.Results and discussionThe results showed that adaptation to drought stress was closely related to the recovery ability of plants. Drought stress caused a decrease in chlorophyll a, chlorophyll b, total chlorophyll, carotenoid, protein and proline, yield, and yield components. The reduction of these traits was more remarkable at six days after stress. However, during the recovery time remarkable increase was observed in these traits. The results showed that the correlation between H2O2 and MDA was significant and positive. Furthermore, drought stress increased the amount of H2O2 and MDA, which increased the activity of antioxidant enzymes (catalase, polyphenol oxidase, and peroxidase). An increase in the intensity and duration of the drought stress also caused an increase in proline (63%), H2O2, (19%), and MDA (110%) content, and the activity of CAT (33%), PP0 (56%), and POX (24%) compared to the control treatment. An increase in the intensity and duration of the drought stress also caused an increase in H2O2 and MDA content and the activity of antioxidant enzymes. In addition, in the recovery conditions, a significant reduction in the destructive effects of stress (H2O2, MDA content) and the activity of antioxidant enzymes was visible. The results of the present study indicated that the effects of drought stress on lentil cultivars' yield and yield components (seed numbers, number of pods, 100-seed weight, and seed yield) were varied. Drought stress at the flowering stage decreased the number of seeds (20%) and pods per plant (37%), and 100-seed weight (16%), which led to 29% yield losses. Although the Gachsaran cultivar had the highest yield under normal conditions. However, under drought stress conditions Gachsaran and Sepehr cultivars showed the highest plant yield. On the other hand, the Namin landrace exhibited the lowest yield (40%) under stress conditions.ConclusionThe water stresses markedly increased the reactive oxygen species (ROS) level and impaired the biosynthesis of the photosynthetic pigment, resulting in the reduction of plant growth and yield with fewer seeds and pods number per plant. However, re-irrigation (recovery) remarkably improved plant growth and reduced the negative effects of drought stress, such as reducing the amount of MDA and H2O2 and improving the activity of antioxidant enzymes and proline content. In conclusion, based on physiological traits Gachsaran, and Sepehr cultivars seem to be suitable cultivars for culture in the regions challenged with water deficit stress.
Breeding plants for stress conditions
Maryam Harati Rad; Nafiseh Mahdinezhad; Reza Darvishzadeh; Barat Ali Fakheri; Mitra Jabbari; Sorour Arzangh
Abstract
IntroductionMaize is a fast-growing plant that absorbs a lot of nutrients from the soil, indicating the need for the availability of various nutrients, including micronutrients, during its growth and development. Zinc is one of the most important micronutrient elements for this plant, which has many ...
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IntroductionMaize is a fast-growing plant that absorbs a lot of nutrients from the soil, indicating the need for the availability of various nutrients, including micronutrients, during its growth and development. Zinc is one of the most important micronutrient elements for this plant, which has many roles. Zinc deficiency is one of the global problems for grain production, and the genotype of the plant has a major effect on the absorption of zinc from the soil or the use of zinc inside the plant. Investigations have shown that the accumulation of micronutrients in seeds is genetically controlled. Knowledge on genetic diversity, in addition to preserving the genetic reserves of plants, also helps to use them effectively and better in plant breeding programs. Study of genetic diversity is a process that reveal any difference or similarity among species, populations or individuals using special statistical methods and models on molecular or morphological traits.Materials and methodsIn this research, 95 maize inbre lines were assessed under optimum and zinc deficiency conditions using α-lattic design with two replications in Zabol Agriculture and Natural Resources Research Center, during 2 successive crop years (2020 and 2021). The investigated lines were obtained from Razi University of Kermanshah, Khorasan Razavi Agricultural and Natural Resources Research and Education Center and Seed and Plant Improvement Institute. Zinc treatment was applied before the beginning of the reproductive stage at the stage of 4, 6 and 10 leaf stages. Zinc fertilizer was added to the ground along with water in the early hours of the day (due to low air temperature). For each genotype in each experimental unit, five plants were randomly selected and the desired traits were measured. The number of 29 traits, including phenological, morphological and yield-related traits were measured. Combined analysis of variance of the studied traits in both environments was performed using SAS 9.4 software. Stepwise regression was performed using the "olsrr" package based on Pearson's correlation coefficient; calculated using the "corrplot" package in R software. Also, in order to more accurately interpret the results of correlation and stepwise regression, path analysis was performed on the traits entered into the final regression model in PATH 2 software. Hierarchical clustering by Ward's method on standardized data was conducted by "cluster and factoexta" packages. Factor analysis were conducted in R software by means of the "FactoMineR" package.Results and discussionThe results showed that there is a significant statistical difference among the studied lines in terms of all the investigated traits. Based on step-by-step regression and path analysis, the number of seeds in the cob and the weight of 100 seeds were determined as important traits affecting economic yield under optimum and zinc deficiency conditions. By cluster analysis, the studied lines were classified into 5 and 4 clusters, respectively, in terms of the investigated traits under zinc deficiency and optimal (normal) conditions. Based on mean comparison of investigated traits in clusters of the hierarchical method, 11 lines in the first cluster (Ma001, Ma023, Ma039, Ma043, Ma044, Ma057, Ma062, Ma065, Ma100, Ma112, Ma117) were identified as sensitive genotypes to zinc deficiency conditions. Thirty lines with the highest values for most of studied traits including Ma004, Ma006, Ma015, Ma017, Ma018, Ma019, Ma020, Ma021, Ma027, Ma030, Ma031, Ma032, Ma035, Ma038, Ma049, Ma055, Ma064, Ma072, Ma075, Ma096, Ma098, Ma104, Ma105, Ma107, Ma108, Ma111, Ma114, Ma123, G703, Simon in the fourth cluster were identified as tolerant genotypes to zinc deficiency conditions. The results of principal component analysis confirmed the results of cluster analysis. In optimum conditions, the first seven components and in zinc deficiency conditions, the first eight components had eigenvalues greater than one, which in total explained 79.77% and 78.99% of proportion of total variance, respectively.ConclusionThe results showed that there is a wide diversity among the studied lines in terms of traits related to the seed yield in both optimum and zinc deficiency conditions, which is valuable for the exploitation of these lines in order to developing tolerant lines to withstand zinc deficiency stress. In this regard, in order to obtain hybrids tolerant to zinc deficiency with higher economic performance, it is suggested to cross tolerant lines in this research to benefit from the phenomena of transgressive segregation and heterosis.AcknowledgementThe authors would like to express their sincere gratitude to the esteemed Research Deputy of Zabol University for the financial support provided for this project, identified by the code UOZ-GR-158-3014.
Breeding plants for stress conditions
Maesomeh Salehi; Farhad Dehghani; Yousef Hasheminejhad; Alidad Karami; Sardar Keshtkar
Abstract
IntroductionQuinoa is a dicotyledonous plant from the Amaranthaceae family. Due to the high nutritional value, several breeding programs have been started on quinoa in different parts of the world. The goals of the breeding programs are to increase yield, reduce sensitivity to day length, increase seed ...
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IntroductionQuinoa is a dicotyledonous plant from the Amaranthaceae family. Due to the high nutritional value, several breeding programs have been started on quinoa in different parts of the world. The goals of the breeding programs are to increase yield, reduce sensitivity to day length, increase seed size, reduce seed saponin content, and resistance to powdery mildew and seed color. The purpose of this research is to select high-yielding and adapted quinoa lines using different parametric and non-parametric methods.Materials and methodsThe advance quinoa line NSRCQ8 (B), NSRCQ7 (C), Sadoq (D), NSRCQ9 (E) with the Titicaca as control (T) in five regions, Yazd (Sadoq Salinity Research Farm, National Salinity Research Center), Sabzevar (Sabzevar Research Station), Shiraz (Khorameh), Bushehr (Ahram) and Iranshahr (Bampur) were evaluated in the form of randomized complete block design during two years 2019-2019. Planting date in Sabzevar was August 15 with irrigation water salinity of 2.8 and soil saturated extract salinity of 4.5 dS m-1, Yazd was 23th of Augest with irrigation water salinity of 12 and soil saturated extract salinity of 16.4 dS m-1, Shiraz on August 20 and in the second year, August 25 with irrigation water salinity of 11.2 and soil saturated extract salinity of 8.5 dS m-1 and Iranshahr on December 15 with irrigation water salinity of 2.8 and soil saturated extract salinity of 9 dS m-1 and Bushehr 22nd of November and in the second year on the first day of January with the irrigation water salinity of 6 and the salinity of the saturated soil extract of 10 dS m-1 and the planting date of the first year of Gorgan was the first of March without the need for irrigation. Yield and weight of 1000 seeds, saponin content and size of seeds were measured. The saponin content was determined using the method of Koziol, 1991. Bartlett's test was performed to check the uniformity of variance of environments and then statistical analysis was performed with SAS software. For the purpose of statistical analysis, line was defined as a fixed factor and year and place were defined as random factors, and the F test was performed according to the mathematical expectation of mean square of variation sources. Considering the significance of the interaction effect of genotype in year and place, stability analysis was done using different parametric and non-parametric methods with Stabilitysoft software.Results and discussionThe results of combined analysis showed that the interaction effect of place and year on grain yield and foam height was significant. The interaction effect of line and place in year on measured traits was significant. The interaction effect of year and location on grain yield and foam height was significant. The results of simple mean comparison showed that the highest grain yield belonged to line D. The thousand kernel weight of line D was 2.6 g on average and 40% of the seeds were placed in the large class. The lowest loss percentage related to D line was 9%. Stability analysis with GGEbiplot method showed that line D is located at the top of the polygon and showed a high private adaptability with all environments except Bushehr in the first year. According to Wricke (1962) (Wᵢ²) line D was ranked 1. According to Finlay and Wilkinson's index (bᵢ), number less than one is the least sensitive to environmental changes, and line D had the lowest (0.9). Eberhart and Russell index (s²dᵢ) showed that line D was ranked 1. Line D is ranked 1 based on Shukla's index (σ²ᵢ). Total rank stability statistic (KR) as another measure to determine the stability of genotypes was presented by Kang. Based on this, the genotype with the lowest value is selected as the most stable. The lowest amount was observed in line D (2) and the highest amount was observed in line B (6). Based on the average of the total ranks, line D (1.44±1.09) had the most stability and line B had the least stability based on parametric and non-parametric indicators of stability. Based on the results of GGEbiplot method and non-parametric and parametric methods, line D had the highest performance and stability.ConclusionEvaluating parametric and non-parametric methods and GGEbiplot method showed similar results and led to the selection of D line. In addition to stability, this line had a yield of 800 kg ha-1 higher than Titicaca variety. The amount of seed saponin was half of that in Titicaca variety. Due to the stability and higher performance of this line, as well as the higher tolerance to salinity, this line was introduced and named as Sadoq variety. Also, in addition to the yield, thousand kernel weight and the amount of saponin were also affected by the environment.AcknowledgmentsThis project has been carried out with the financial support of the Agricultural Research, Education and Promotion Organization. We appreciate all the provincial colleagues.
Salinity stress
Rostam Yazdani Biouki
Abstract
IntroductionSalinity is a major abiotic stress limiting growth and productivity of plants in many areas of the world due to increasing use of poor quality of water for irrigation and soil salinization. Soil and water salinity in semi-arid regions such as Iran have been important threats for plant growth ...
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IntroductionSalinity is a major abiotic stress limiting growth and productivity of plants in many areas of the world due to increasing use of poor quality of water for irrigation and soil salinization. Soil and water salinity in semi-arid regions such as Iran have been important threats for plant growth and agriculture. Distributed in semi-arid and arid parts of the world, ajwain, or sprague, (Carum capticum L.) is a medicinal and industrial plant of the Apiaceae family with white flowers and small brownish fruits. A good source of secondary metabolites, the seeds of ajowan have been used in food and pharmaceutical applications2. A variety of health properties was described for the ajowan seeds, which include antimicrobial, antioxidant, nematicidal, anti-inflammatory, carminative, and sedative effects.Materials and methodsWith the aim of estimation of some growth characteristics of the Ajowan in response to salinity stress, an experiment was conducted in a completely randomized design with 3 replications in a pot in the greenhouse of the National Salinity Research Center during 2020. Experimental treatment includes water salinity levels 0.4 (control), 3, 6, 9 and 12 dSm-1. At the beginning of planting, all the pots were watered with city water until establishment and germination and reaching the desired density. And then to avoid introducing sudden stress to the plant, salinity treatments were gradually increased during a period of 20 days after planting according to each treatment. After 8 months after planting in the stage after flowering, some quantitative characteristics of the plant were measured as follows: plant height, fresh and dry weight of shoots, root dry weight, lateral stem number, relative water content, ion leakage, potassium and sodium of shoots. Analysis of variance of the data was calculated using SAS Ver 9.2 statistical software, and mean comparison was performed using the LSD test at the 5% probability level.Results and discussionThe results showed that all investigated traits were affected by different levels of salinity. As by increasing the salinity from the control treatment (0.4 dS.m-1) to a salinity of 12 dSm-1 caused a decrease of 63% in the height of the plant, 58% in the shoot fresh weight, 42% in the shoot dry weight, 47% in the root dry weight, 13% in relative water content and 45% in potassium. Also, increasing salinity from control treatment 0.4 to 12 dSm-1 caused an increase in the amount of sodium and ion leakage by 46% and 11.5%, respectively. In many studies, reports indicate a significant effect of salinity on the reduction of the growth characteristics of Ajowan plants. It seems that in the present study, with the increase in salinity stress level, plant height decreased due to the harmful effects of salinity. Correlation results showed that the highest effective traits on dry weight of shoot dry weight included potassium and ion leakage. One of the reasons for the decrease in dry matter was the increase in ion leakage and the decrease in potassium content of the plant, and correlation and regression studies also indicated a high correlation between ion leakage and potassium content with plant dry matter.ConclusionThe results indicated that the growth traits and related to the yield of the Ajowan decreased significantly with the increase in irrigation water salinity. Also, salinity stress significantly decreased the relative water content and decreased the amount of potassium and the ratio of potassium to sodium and increased the ion leakage and sodium percentage of the plant. Correlation and regression studies also indicated a high correlation between ion leakage and potassium content with plant dry matter. The changes in plant dry matter yield between other salinity levels, 3, 6, and 9 were not significantly different from plants under the control treatment. In general, we can recommend ajwain plant as one of the promising salinity-tolerant medicinal plants for further studies.
Drought stress
Pari Hasanvand; Golam Reza Zamani; Ali Akbar Maghsoudi Moud
Abstract
IntroductionOilseeds are the second main source of human food after cereals. Safflower is an oilseed crop with favorable and unique characteristics that make it a valuable oilseed crop. Safflower due to having long roots and the high ability for absorbing water from deep soil layers, is considered as ...
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IntroductionOilseeds are the second main source of human food after cereals. Safflower is an oilseed crop with favorable and unique characteristics that make it a valuable oilseed crop. Safflower due to having long roots and the high ability for absorbing water from deep soil layers, is considered as a low water-tolerant plant; but after the rosette stage, it becomes more sensitive to water stress such that since the first signs of inflorescence emergence up to the middle of the grain-filling period, it shows more sensitivity to this kind of stress. Increasing need for oil production on one hand and increasing levels of drought due to world climatic changes on the other hand makes it necessary to seek for more water stress tolerant plants such as safflower with relatively high yield capacity under low water content areas. Meanwhile the area under cultivation of safflower should increase. Agricultural and environmental factors can affect safflower seed yield and seed oil content. Therefore, it is important to investigate different environmental factors and their effects on growth and yield performance of safflower plants. Limitations of water resources makes it more difficult to grow safflower plants. Furthermore increasing levels of per capita oil consumption in Iran indicates that oilseed production must increase. Therefore, One of the objectives of this research was to identify and evaluate species and cultivars resistant to water stress and to find the plant stages sensitive to water stress.Materials and methodsIn order to evaluate the effects of water stress on some morphological, yield and yield components of different safflower cultivars, an experiment was carried out as split plots based on randomized complete blocks design with three replications at the experimental field 56° 58' E; 30° 15' N; 1754 meters above sea level of Faculty of Agriculture, Shahid Bahonar university of Kerman, Iran during 2019-2020 growing season. Water stress applied at three levels including 40, 60 and 100% of full crop water requirement in the main-plots and 6 Iranian safflower cultivars including Faraman, Goldasht, Golmehr, Parnian, Padideh and Sina assigned to the sub-plots. Physical and chemical properties and nutrient elements content of the soil before planting were measured using samples taken from of 0-30 cm soil depth of experimental location. Seeds planted manually and plots fully irrigated immediately after planting. Thereafter, plants irrigated throughout the growth period based on the calculated values of the water requirement of the plant.Results and discussionBased on results, the treatment 40% of the plant water requirement had a significant reduction effect compared to other treatments of water stress on the studied traits in all investigated cultivars. The results Data analysis showed that water stress had not a significant effect on lateral branch number, but it causes a significant reduction in all traits, Including the plant height, number of heads per plant, number of seed per head, head diameter, 1000 seed weight, seed oil content, oil yield and seed yield. Significant differences found among cultivars in term of all other plant characteristics. Meanwhile, Highest values of 1000 seed weight (37.2 g), oil yield (461.8 kg.ha-1) and seed yield (1592.6 kg.ha-1) observed in Faraman cultivar. The Interaction effects between irrigation treatment and cultivar were significant in case of number of heads per plant, number of lateral branches, oil yield and seed yield. However, the Faraman cultivar had more grain yield potential in water stress conditions than the other investigated safflower cultivars.ConclusionGenerally, results showed that the reaction of the six cultivars investigated in terms of plant height, number of heads per plant, number of seed per head, number of lateral branches, 1000 seed weight, head diameter, seed oil content, oil yield and seed yield were affected by water stress. The highest values of 1000 seed weight, oil yield and seed yield among the investigated safflower cultivars were related to Faraman cultivar. Meanwhile, cultivar Faraman showed higher seed yield potential under water stress conditions compared to the other cultivars. Therefore, to achieve higher yield, Faraman recommended to be grown under low soil water content condition.
Biotechnology and environmental stresses
Zohreh Hajibarat; Abbas Saidi; Zahra Hajibarat
Abstract
IntroductionAbiotic stresses can disrupt future food security, which simultaneously implies the importance of genotype screening in stressed environments. Drought and phosphorus stresses have great effects on the growth and development of maize. Soil dryness and phosphorus deficiency cause similar effects ...
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IntroductionAbiotic stresses can disrupt future food security, which simultaneously implies the importance of genotype screening in stressed environments. Drought and phosphorus stresses have great effects on the growth and development of maize. Soil dryness and phosphorus deficiency cause similar effects and illicit similar defence mechanisms in plants (Xia et al., 2021a). Drought and phosphorus stresses in the root zone can cause active oxygen accumulation in plants. In order to deal with excessive accumulation of active oxygen, plants activate their oxidative defence mechanisms through enzyme or non-enzymatic routes. Oxidative stress caused by excessive accumulation of reactive oxygen species is one of the important physiological factors affecting plant growth and development under stress conditions. The sensitivity of genotypes to water deficit is different and they can be classified into two groups, tolerant or sensitive. Maize (Zea mays L.) is one of the most important crops in the world for food security, as it feeds millions of people. Abiotic stress can create significant challenges in maize production. The present study aimed to determine the effects of phosphate and PEG stresses on the physiological and biochemical traits in the maize cultivars.Materials and methodsMeasured traits in leaf and root tissues were analysed among five maize cultivars under PEG and phosphate stresses. Also, analysis of biochemical traits such as chlorophyll a/b and carotenoids in maize seedlings under PEG 20% and low phosphate were analysed. The five maize cultivars were exposed to PEG 20% and low phosphate stresses and sampled at two-time points after treatment (24 and 48 h). This experiment was carried out as a factorial experiment in the form of a completely randomized design with three replications. In this study, antioxidant enzymes such as catalase, ascorbate peroxidase, and peroxidase activity were measured in leaf and root tissues. Further, PCA, dandraogram and correlation of physiological traits, biochemical and morphological traits were analysed. Statistical analysis was performed using SPSS. Differences across tissues were analysed using one-way ANOVA. Duncan’s test was used to compare the treatment means at P<0.05. Values represent the means of three replications per treatment. Principal Component Analysis (PCA) and correlations were performed using SPSS 22.Results and discussionBased on the cluster analysis, the cultivars were grouped into three classes. The cluster I included Fajr, Paya, and Dehghan whereas, Kosha and Taha cultivars were placed in the clusters II and III, respectively. Also, there was a significantly positive correlation at the probability level of one percent between the content of chlorophyll a/b and root anthocyanin and total chlorophyll content. Correlation between biochemical and physiological traits is shown in Figure 2. The chlorophyll a showed a positive and significant correlation with total chlorophyll and carotenoid contents. The chlorophyll b showed a positive and significant correlation with total chlorophyll content and root anthocyanin. PCA was performed on physiological and biochemical traits to fully investigate the various factors that play essential roles in the drought indices. The cumulative contribution rate of the total changes of PC3 reached 97%. According to PCA analysis measured by correlation matrix and biplot analysis method, it was found that these parameters can be used to evaluate the response of maize genotypes to abiotic stresses under different environments. The relationships between biochemical traits and genotypes is shown graphically in two segments of PC1 and PC2.ConclusionPrincipal component analysis (PCA) and measured traits showed that Fajr, Paya, and Kosha cultivars can show high performance under studied stress conditions. In the present study, the Kosha cultivar was shown to be relatively water stress and low phosphate tolerant due to improved antioxidant, chlorophyll, and carotenoids activities under abiotic stresses.
Salinity stress
Mitra Jabbari; Nafiseh Mahdinezhad; Khaled Salimi
Abstract
IntroductionSalinity affects about 1.7 million hectares of agricultural land in Iran, which poses a serious challenge for wheat production, as the most strategic crop in the country. Therefore, identifying wheat genotypes with salinity tolerance and selecting effective traits for accelerating the breeding ...
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IntroductionSalinity affects about 1.7 million hectares of agricultural land in Iran, which poses a serious challenge for wheat production, as the most strategic crop in the country. Therefore, identifying wheat genotypes with salinity tolerance and selecting effective traits for accelerating the breeding process are crucial objectives.Materials and methodsThe experiment was aimed at assessing the response of 12 wheat cultivars to different levels of salinity using NaCl concentration as salt stress at early seedling stage under hydroponic conditions. A factorial experiment based on randomized complete block design with three replications was conducted at the research greenhouse of the Agriculture Faculty, University of Zabul, during the 2020 cropping seasons. 12 wheat cultivars (Shiraz, Falat, Durum, Gascogne, Mahdavi, Alvand, Cross Azadi, Roshan, Star, Tous, Hirmand and Cross Bolani) were irrigated with four concentrations of NaCl (0, 100, 200 and mM). The physiological and biochemical traits of wheat cultivars, including seedling fresh mass, ascorbate peroxidase, glutathione peroxidase, catalase, proline, sodium, potassium, and potassium to sodium ratio (K+/Na+) were recorded at four weeks after seed germination.Results and discussionThe results showed that the amount of ascorbate peroxidase, glutathione peroxidase, catalase, proline and sodium in the leaves of wheat seedlings were increased with an increase in salinity level. In contrast, the seedling fresh mass, potassium content and K+/Na+ were decreased with an increase in salinity level. The increase of ascorbate peroxidase, glutathione peroxidase, and catalase activities, representing the main enzymatic H2O2 scavenging mechanism in wheat cultivars. In NaCl treated seedlings, Falat, Mahdavi and Cross Bolani cultivars showed higher ascorbate peroxidase than other cultivars tested. In contrast, high level of catalase was recorded in Alvand cultivar. In the other hand, maintain the high level of proline and potassium to sodium ratio are the main mechanisms for tolerance to salinity in Shiraz and Roshan cultivars, respectively. Wheat cultivars showed different response to the increase in salinity level, while in Roshan, Mahdavi, Hirmand and Cross-Bolani cultivars, the increase in salinity level had less effect on the seedling fresh mass than other cultivars, but different patterns of changes in physiological and biochemical traits were observed in these cultivars. Salinity resistance in Mahdavi cultivar was directly related to the increase of ascorbate peroxidase and catalase, but on the other hand, in Roshan cultivar, salinity resistance was related to maintaining a high level of potassium to sodium ratio. Potassium uptake is vital for plant growth but in saline soils because of their shared transport system and physicochemical similarities, the sodium in the soil solution competes for uptake with potassium and can lead to potassium deficiency. The induced potassium deficiency inhibits growth because it plays a critical role in maintaining cell turgor, membrane potentials, and enzyme activities. In salt-tolerant cultivars of wheat such as Roshan, under salt-stress conditions, limiting sodium uptake and preventing potassium losses from the cell may help to maintain a potassium to sodium ratio in the cytoplasm that is ideal for plant metabolism. Accumulation of high amounts of proline is often related with the salt tolerance nature of crop cultivar and high proline accumulation in the salt–tolerant cultivar than in their salt–sensitive are reported previously. The regression coefficients indicated that seedling fresh weight (R2=0.89), potassium (R2=0.86) and the ratio of potassium to sodium (R2=0.69) were the most reliable predictors of the effects of increasing sodium chloride concentration. These variables accounted for a large proportion of the variance in the response variable and had significant p-values.ConclusionAccording to the results of this experiment, it can be concluded that seedling fresh weight, potassium, and the ratio of potassium to sodium are more suitable criteria for selecting among cultivars under salt stress conditions.
Cold stress
Arezoo Akbari; Vali Rabiei; Taher Barzegar
Abstract
IntroductionPhysalis (Physalis peruviana L.) is a perennial plant belonging to the Solanaceae family, but it is grown commercially as an annual crop. Low temperature has been reported as one of the most restraining environmental factors for agricultural crops, particularly vegetables. Cold stress causes ...
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IntroductionPhysalis (Physalis peruviana L.) is a perennial plant belonging to the Solanaceae family, but it is grown commercially as an annual crop. Low temperature has been reported as one of the most restraining environmental factors for agricultural crops, particularly vegetables. Cold stress causes symptoms such as wilting, reduced growth and photosynthetic rate, chlorosis, necrosis, discoloration, abnormal ripening, increased susceptibility to diseases, ion leakage from cell membranes, and changes in respiration and ethylene production in plants. Amino acids are one of the possible approaches that induce cold stress tolerance in plants. Phenylalanine is one of the essential amino acids that is used as a nutritional enhancer, amino acid injection, and complex amino acid preparation. Foliar application of amino acids such as L-phenylalanine during plant growth increased anthocyanins and phenolic compounds contents in grape and strawberry fruits and cysteine also contains sulfur as an amino acid which is widely present in bacteria, yeast, plants, animals and certain single cells. Spraying amino acids on plants is one of the modern methods. Selenium (Se) and its salts protect plants against biotic (pathogens and herbivores) and abiotic (ultraviolet rays, heavy metals, arsenic) stresses. Also, the findings showed that selenium can effectively stimulate the phenylpropanoid metabolic pathway and it has been specifically determined that it protects plants against biological stresses.Materials and methodsIn order to investigate the effect of low temperature stress during seedling growth stage, and foliar application of amino acids L-phenylalanine (Phe), L-cysteine (Cys) and sodium selenite (Se) on yield and fruit quality of Physalis (Physalis peruviana L.), an experiment was conducted in greenhouse and field of University of Zanjan. The seeds of physalis were sown in seedling trays contain peat moss. The seedlings were grown under normal conditions (25±2 °C/day and 20±2 °C at night with 60-65% RH). The different concentrations of Phe (0.75, 1.5 and 2.5 mM), Cys (0.25, 0.5, and 0.75 mM) and Se (0.25, 0.5, and 1 mg.L-1) was sprayed on the seedling at 4–5th true leaf stage and distilled water was used for control treatment. For the chilling stress treatment of seedlings, plants were transferred to the 4 °C climate chamber for 24 h and two days. The control group (plants without chilling stress) was grown under normal conditions (25±2 °C/day and 20±2 °C at night with 60-65% RH). Plants transplanted to the field and foliar sprayed three times (growth stage, flowering and fruit set stages) with amino acids and Se. Fruits were harvested with the change of calyx and fruit color from green to orange and total fruit yield estimated as a kg.ha-1. Also, chlorophyll and carotenoid contents of leaf, fruit carotenoid, titratable acidity, soluble solids contents, vitamin C ant antioxidant activity were investigated.Results and discussionThe results showed that low temperature significantly decreased total chlorophyll and carotenoid contents of leaves, titratable acidity (TA) and carotenoid contents of fruit, and caused increases in total soluble solid content of fruit, but had no significant difference on fruit yield, vitamin C content and antioxidant activity. Foliar application of Phe, Cys, and Se increased yield and fruit quality. The highest fruit yield (11419.1 kg.ha-1) was obtained in with application of Cys 0.5 mM in plants under low temperature stress. The maximum vitamin C content was obtained in plants sprayed with Phe 0.75 and 1.5 mM under normal condition. Also, the highest fruit antioxidant activity (56.9%) was observed with application of Phe 0.75 mM in plants without cold stress compared to other treatments and plants under stress. The beneficial role of Se and amino acids in increasing antioxidant capacity might be attributed to enhancing antioxidant enzymes activity, phenolic compounds and carotenoids content, which have antioxidant activity.ConclusionTherefore, the use of these compounds specially Phe 1.5 mM, Cys 0.5 mM and Se 1 mg.L-1 are suggested to improve the performance and quality of the fruit under low temperature stress or non-stress conditions.
Salinity stress
Masomeh Nasiri; Babak Andalibi; Saeed Khomari; Esmaeil Goli Kalanpa
Abstract
IntroductionIn many arid and semi-arid regions of the world, including Iran, soil salinization is considered an important obstacle to optimizing the use of agricultural lands. Salinity stress affects the main plant processes, including photosynthesis and the production of photosynthetic process, and ...
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IntroductionIn many arid and semi-arid regions of the world, including Iran, soil salinization is considered an important obstacle to optimizing the use of agricultural lands. Salinity stress affects the main plant processes, including photosynthesis and the production of photosynthetic process, and with negative effects on these processes, it causes a decrease in plant production. Salicylic acid plays an important role in regulating plant growth, development, ripening and plant defense responses. Application of appropriate concentration of salicylic acid increases tolerance to abiotic stresses, thus not only reducing the destructive effects of stress but also increasing tolerance to biotic stress. However, the concentration of salicylic acid used and its method of application, including foliar spraying, depend on the plant species, and therefore contradictory results can be reported. One of the management strategies for improving the conditions of saline soils is the use of organic amendments, including biochar. In most of the studies, it has been stated that biochar increases the availability of micro and macronutrient elements (directly) and improves physical, chemical and biological characteristics such as increasing cation exchange capacity, dispersion, improving soil structure (indirectly), so increasing microbial biomass and improving soil fertility cased to increasing growth. Materials and methodsThe experiment was carried out factorial experiment in the form of a randomized complete block design with four replications. Factors include biochar in four levels (control without biochar, simple biochar 2.5% by weight in soil and biochar 25% modified with phosphoric acid and sulfuric acid by weight in soil) and salicylic acid foliar spraying in three levels (control, 0.5 and 1 mM) and soil at three levels (normal soil as a control, saline soil at two levels of 4 and 8 dS m-1). Salinity treatment was applied in two stages of planting, at the same time as the first irrigation and when the seedlings were fully established in the soil. To prepare modified biochar, 10 grams of biochar were added with 200 ml of phosphoric acid and one molar sulfuric acid. Foliar spraying with salicylic acid was done based on the determined levels, in two phases, early and late flowering. The desired traits were selected by choosing the number of plants randomly after applying the treatments, and the samples were weighed to evaluate the dry weight after drying in the oven.Results and discussionThe results of variance analysis showed that the highest plant height in the first and second year of the experiment was obtained from the treatment of 0.5 and 1 millimolar salicylic acid, respectively, combined with the application of simple biochar of 2.5% by weight in the condition of no soil salinity stress. The application of 0.5 mM salicylic acid with biochar modified with phosphoric acid caused the highest number of leaves per plant in the absence of salinity. With increasing soil salinity concentration, the dry weight of bean plants decreased significantly. The application of biochar, especially simple biochar of 2.5% by weight, reduced the negative effects of salinity on these traits. In high soil salinity, the application of salicylic acid, especially combined with the application of simple biochar, improved the grain in the pod. The application of biochar modified with sulfuric acid in all treatments resulted in a significant decrease in grain yield; however, salicylic acid at different levels of salinity combined with the application of simple biochar showed a significant positive effect on grain yield. The highest level of salicylic acid with biochar modified with sulfuric acid showed negative results at different salinity levels on the number of root nodules and root dry weight. ConclusionBy increase of soil salinity, the dry weight of bean plant decreased significantly, although at high concentrations with the application of biochar, especially simple biochar of 2.5% by weight, the negative effect of salinity on the plant weight decreased to some extent. The application of different levels of biochar in extreme salinity conditions not only did not improve the condition of this trait, but also caused a decrease in this trait compared to the absence of biochar application. Biochar, especially simple biochar, had a positive effect on increasing the number of pods in the plant in conditions of no salinity or moderate salinity. It was concluded that the positive and significant effects of different levels of salicylic acid on the morphological characteristics of the root, including its length, volume and weight, were particularly evident in high soil salinity stress.
Flooding stress
Fatemeh Askari Foroshani; Afrasyab Rahnama; Mousa Meskarbashi; Iman Kamranfar
Abstract
IntroductionWaterlogging stress is a common agricultural problem in many regions across the globe. Crop productivity is threatened primarily by waterlogging in rainfed areas. Plant growth and crop production is constrained severely by waterlogging in many regions around the world. Waterlogging significantly ...
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IntroductionWaterlogging stress is a common agricultural problem in many regions across the globe. Crop productivity is threatened primarily by waterlogging in rainfed areas. Plant growth and crop production is constrained severely by waterlogging in many regions around the world. Waterlogging significantly reduces the grain yield. Moreover, oil yield reduces mainly due to a significant decrese in grain yield under waterlogging stress condition. Waterlogging at different growth stages has different effects on crop growth and yield. In most crop plants, it was shown the different adverse effects of waterlogging on yield determination at the vegetative and reproductive stages. However, the effects of waterlogging stress at different growth stages on safflower under field conditions is not yet known. Materials and methodsIn the current study, in order to study of the influence of waterlogging stress at different growth stages on the morphological traits and grain yield of safflower under field conditions, a field experiment was carried out during 2020-2021 growing season in a split plot arrangement in randomized complete blocks design using three replicates per treatment. The study site was located at the research farm of Shahid Chamran University of Ahvaz, Iran. The plants were grown in the filed to ensure the environmental conditions found in flooded soils. Three waterlogging treatments were applied to plants as main plots: Well-drained controls watered weekly, mild stress (waterlogged for 24 h) and severe stress (waterlogged for 48 h). Waterlogging treatments implemented at the vegetative and reproductive stages as sub plots. After the waterlogging period, waterlogging treatments were watered with sufficient water (80% field capacity) until the end of the experiment. Results and discussionThe waterlogging treatments at vegetative and reproductive stages significantly decreased biological yield, grain yield, number of sub-branches, branche number, capitulum number per plant, grain number per capitulum, grain number per plant, 1000-grain weight and oil yield. There was no significant difference between growth stages in terms of all traits except for capitulum number per plant and the number of sub-branches. The mild and severe waterlogging stress at both growth stages was led to a significant reduction in grain yield by 34 and 39%, respectively, compared to control. The waterlogging treatments at different growth stages differently reduced the grain yield. The maximum decrease was found when waterlogging occurred for 48 h at the reproductive stage. The reduction in the number of sub-branches was associated with capitulum number per plant and grain number per plant. Under waterlogged conditions, the reduction in capitulum number per plant was mainly due to the decrease in the number of sub-branches. ConclusionThese findings indicate that safflower is more sensitive to waterlogging at the reproductive stage. The effect of waterlogging stress on grain and oil yield varied between two growth stages and waterlogging durations. Under waterlogging condition, grain yield loss occurred mainly due to a decrease in the number of sub-branches, branch number, capitulum number per plant, grain number per head and grain number per plant, which led to a significant decrease in grain yield and ultimately reducing the oil
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