تحمل خشکی

In this study, the anatomical evaluation of two sunflower lines DM-2 and H158A/H543R was done based on a completely randomized design with three replications at the 8-leaf stage under normal and drought stress of 30% of the pot capacity. For this purpose, the thickness of the collenchyma, epidermis, brain parenchyma and skin parenchyma tissues of the stem was measured after staining using a reticulated lens and optical microscope in each one of normal and drought stress conditions and the number of cells in collenchyma tissue layer was counted. The anatomical comparison of two tolerant and sensitive lines of sunflower was also done after recovery. The results of analysis of variance showed the influence of stem anatomy from stress conditions. Epidermal and brain parenchyma tissues showed the highest thickness in the tolerant line under normal conditions. The highest thickness of skin parenchyma tissue was observed in the tolerant line under drought stress conditions as well as in the sensitive line under normal conditions. In the recovery conditions, a significant difference was observed in the thickness of epidermis, brain parenchyma and skin parenchyma tissues of studied lines. The results showed that the tolerant line has the highest thickness of skin parenchyma tissue, so the increase of skin parenchyma tissue is confirmed as part of the important mechanisms of irreversible resistance.

Cowpea is a multiple-purpose drought-tolerant leguminous pulse crop grown in several dry tropical areas. However, detailed genetic information is lacking in many Asian countries, limiting the success of breeding programs. In this research, in order to evaluate the drought tolerance of 30 cowpea genotypes, an experiment was conducted in the form of a completely randomized block design with three replications in two conditions without stress (60 ml evaporation from the evaporation pan) and drought stress (120 ml liter of evaporation from the evaporation pan) was done in field conditions. The genotypes were significantly different from each other in terms of agro-morphological traits. The cluster analysis grouped the genotypes into four clusters. In general, based on bi-plot analysis, cluster analysis and correlation, genotypes 4, 6, 14, 28 and 29 in normal conditions and in drought stress conditions genotypes 5, 6, 14, 28 and 29 have the highest yield. They had the seed. Due to the fact that genotypes 28, 29 and 14 have a lower yield under drought stress than normal, they were identified as tolerant genotypes, which had higher yields than the control cultivars. Which might represent promising cowpea genetic resources for improved drought tolerance breeding.

As one of the most important cereals, bread wheat is an essential part of food security in the world, which supplies one-fifth of the total calories of the world population. Nowadays, the yield of wheat has been affected by climate change-driven drought as one of the most important abiotic stresses that has become an important threat to food security in the world. Root and stomatal traits are especially important in breeding plants to withstand drought stress. Stomata play a key role in controlling carbon dioxide uptake and water loss through transpiration. Therefore, stomatal characteristics are used as indicators of water status and plant growth, especially in drought stress conditions. Having a wide range of physiological and morphological characteristics, roots play an essential role in absorbing water and nutrients. They are also the first organ that sends signals to control the stomata in response to dryness. Therefore, the difference in the structure of the root system can cause the difference between the performance in different cultivars. This study was conducted to investigate stomatal characteristics and their relationship with the root system and plant performance in 24 bread wheat lines and cultivars.

To investigate the relationship between stomatal dimensions and density with the root system, an experiment was conducted on 24 bread wheat genotypes in the form of a randomized complete block design with three replications in the rainfed conditions of the research farm at Zanjan University Faculty of Agriculture in the crop year 2018-2019. In this experiment, PVC pipes were used to study the root system. Twelve seeds were planted in each tube, which were thinned to seven after germination. In each experimental unit, there were two tubes for each genotype, one of which was used to evaluate traits and final yield, and the second tube was used for root studies. Stomatal traits, including the length and width of stomata and number of stomata per unit area, root traits including root length, root diameter, root volume, root surface, and root biomass, and seed yield were measured in the end. The resulting data from the measured traits were analyzed in the form of a randomized complete block design, and the averages were compared using the LSD method. The data were analyzed using multivariate statistical analyses, including regression analysis, path analysis, and factor analysis, and cluster analysis was used to group genotypes. Statistical calculations were done using SAS 9.0 and SPSS 21 software.

The results of analysis of variance and mean comparison showed high variability among genotypes for all measured traits. The results of the mean comparison of genotypes showed that genotypes 2, 5, 8, and 16 had the highest yield, and genotype 23 had the lowest yield among the examined genotypes. The highest number of stomata on the upper and lower leaf surfaces belonged to genotypes 5 and 2. In terms of root traits, the highest diameter, volume, length, root surface, and root dry weight at a depth of 0-25 cm were recorded for genotypes 2, 3, 18, and 5, respectively. There was a high and significant correlation between the yield and the number of stomata on the upper and lower leaf surfaces, the length and width of  the stomata on the upper leaf surface, diameter, volume, dry weight, and root surface at a depth of 0-25 cm in the soil. Based on the results of stepwise regression analysis, two variables, the number of stomata on the lower leaf surface and root dry weight at a depth of more than 25 cm explained 91.4% of the changes in grain yield. According to the results of the causality analysis of the number of stomata on the lower leaf surface, the most direct effect had a positive effect on seed yield. The results of factor analysis grouped the studied traits into three factors with 82.48% variability justification. The shares of the first, second, and third factors to explaining data changes were 48.86%, 24.62%, and 8.99%, respectively. Based on the plot obtained from factor analysis, genotypes 2, 5, 8, and 16 had high values for the first and second factors. According to the coefficients of the factors, it can be claimed that the genotypes located in this area have high performance, a high number of stomata, and strong root traits, which were found at the soil depth of 0-25 cm. For this reason, these are the genotypes that could produce high yields by absorbing water from the surface layers of the soil by having a large number of stomata and carrying out more photosynthesis. Moreover, the investigated genotypes were divided into three groups from cluster analysis by the ward method and Euclidean distance. Genotypes 2, 5, 8, and 16 were placed in the first group and had the highest mean values for grain yield traits, number and width of stomata on the upper and lower leaf surfaces, and root traits including diameter, volume, and dry weight at a soil depth of 0-25 cm, and root diameter at a depth greater than 25 cm. The lowest values for stomatal length were observed in both leaf surfaces. These were the best genotypes for cultivation in dry conditions.

A strong superficial root system can provide the plant with water from scattered rains that occur with low frequency at the end of the growth period. On the other hand, the increase in the number of stomata along with their smaller size reduces leaf pores and enables a faster response of the stomata, and the rapid response of the stomata maximizes water use efficiency. Therefore, having a strong superficial root system along with high stomatal density can increase seed yield in dry conditions.

 Drought is one of the most important global threats to food production, in addition to that, climate change and the increase in the global population also widen the dimensions of this problem. One of the ways to solve this problem is to create new cultivars with greater tolerance to drought stress. Wheat has been one of the most important sources of human food all over the world and it is used in various food products and processing industries. Wheat together with rice and corn provide more than 60% of calories and protein needed for human nutrition. In areas like Iran, where most of the rain occurs in winter and early spring, wheat will face water shortage and drought stress at the end of the growing season. In crops, one of the effective methods that can minimize the effect of this phenomenon in combination with other methods of water deficit management is the use of high-yielding and drought-tolerant cultivars. Despite the numerous scientific sources published in this field, there are still many gaps in these studies, so studying the effects of drought stress is always a research priority. Ilam province, as one of the irrigated wheat production areas, suffers from the lack of cultivars that are resistant or tolerant to low irrigation conditions, so investigating the response of different wheat genotypes in low irrigation conditions as low input production systems is very important and is addressed in this study. 

In order to evaluate some bread wheat genotypes under normal and drought stress co ditions, 36 wheat genotypes were evaluated in the form of a randomized complete block design in three replicates in the crop year of 2019-2019 in Darehshahr city located in Ilam province. The examined traits include spike length, spike number per plant, spike length, peduncle length, sub-peduncle axis, flag leaf length, flag leaf width, number of stem nodes, plant height, number of spikes per plant, number of seeds per spike, number of seeds per plant. plant, number of tillers, hundred seed weight, single plant seed weight and seed yield. Based on performance under stress (Yp) and normal (Ys), drought tolerance indices such as average productivity tolerance index, harmonic mean, geometric meanproductivity (GMP), stress sensitivity index, stress tolerance index, performance stability index (YSI) and Relative Stability Index (RSI) and Performance Index (YI) were calculated. The mean comparison test was performed using Duncan's method and using R software. Simple correlation (Pearson), decomposition into components, decomposition into factors were also performed between the tested traits. SAS 9.1 statistical software was used for statistical analysis of traits. 

The results of the analysis of variance in drought and normal stress conditions showed that there was a significant difference between genotypes in all traits at the probability level of 1%. The most important significant correlation coefficient in both conditions between seed yield was related to the seed weight of a single plant and the number of seeds per plant. Considering the high and significant correlation of grain yield under stress and non-stress conditions with drought tolerance indices, higher productivity indices, geometric mean productivity (GMP), geometric mean  and stress tolerance index  as the best indicators. were chosen. It seems that in order to evaluate stress tolerance, the selection of genotypes should be based on several indicators. Factor analysis at the drougth stress condition indicated that the two first factors expalined a total of 97. 57% of the variance. The first factor was called the performance stability factor and the second factor was named theStability Factor. The biplot diagram also showed that the genotypes of no. 13 and 47 were placed in the vicinity of the ranges related to drought resistance indices (STI, MP, GMP, and HM) and were introduced as superior genotypes. 

According to the data obtained from analysis of variance in both normal and drought stress conditions, the genotypes were significant in terms of all traits. The significance of the studied traits indicates the existence of diversity between genotypes in terms of the studied traits, and some of these traits can be used to evaluate stress tolerance. The best genotypes had the best averages for peduncle length of genotype 33, for the number of seeds per plant of genotype 5, for seed weight of a single plant and seed yield of genotype 1. The heat map shows the relationship between drought tolerance based on different yield and drought stress toleranceindices. Considering the high and significant correlation of grain yield under stress and non-stress conditions with drought tolerance indices, average productivity indices, GMP, geometric mean and stress tolerance index were selected as the best indices that are able to distinguish tolerant genotypes from other Screen the genotypes. The yield index (YI) had the highest correlation coefficient with grain yield under stress conditions. Based on biplot results, genotypes No. 13 and 47 were the most tolerant genotypes under drought stress conditions more than other genotypes and were introduced as superior genotypes.

In order to compare 25 genotypes of bread wheat in terms of morpho-physiological and biochemical traits, an experiment was conducted in a randomized complete blocks design with three replications in the rainfed and irrigated conditions at Razi University, Iran, in 2016-2017. GT-biplot was used to evaluate genetic diversity and to identify stable genotypes with high yield and drought tolerance. Combined variance analysis showed that there was high variability among genotypes for the most of traits. Examining the correlation of traits in two environmental conditions showed that morpho-physiological traits; especially yield components, were the most related to yield. The results of the GT-biplot method showed that the first and second principal components explain 41.7% and 40.1% of the total changes in rainfed and irrigated conditions, respectively. Based on the GT-biplot analysis diagrams of genotypes 10, 15, 6, 13, 2, 14, and the Pishtaz cultivar in terms of physiological traits, yield and its components and the traits related to stem and spike in irrigated conditions, and genotypes 10, 15, 6, 18, and 17 in terms of biochemical traits, yield and its components, and traits related to stem and spike in rainfed conditions were recognized as superior genotypes. The genotypes 2 and 6 in irrigated conditions and the genotype 6 in rainfed conditions had the lowest genotype×trait interaction. Finally, the genotypes 10, 15, and 6 were superior in two environmental conditions and the genotype 6 had the least interaction effect in both conditions. Therefore, these genotypes can be used in breeding programs.

Drought stress, as an important constraint to reduce crop yields in Iran. To identify rice genotypes tolerant and sensitive to drought stress during flowering 15 genotypes were studied under two environments (stressed and non–stressed conditions) in a randomized complete block design with three replications at Abbas Abad and Katalom regions during 2018 growing season. To evaluate the susceptibility or tolerance of genotypes to drought stress, traits like yield under non-stress (Yp) and drought stress (Ys) and average yield of all genotypes under stress and nonstress (Ȳs), stress tolerance indicators, arithmetic mean (MP), geometric mean (GMP), harmonic mean (HM), tolerance (TOL), stress tolerance (STI), yield index (YSI), yield index (YI) and sensitivity to stress (SSI) were evaluated. Among the genotypes under study, sixty (54.62) and Ali Kazemi (46.92) showed the highest values for HM index. Shastack based on MP and GMP, shastack (61.04) and Tarom genotype (3.15) and STI index with similar trend to shastack (1.54) and Ali Kazemi (1.08) genotypes, respectively. Stress sensitivity (SSI) and yield stability index (YSI) values were similar for both genotypes of Shirudi (0.32) and Caspian (0.76). Cluster analysis based on 10 indices under drought stress resulted in two groups. Based on the results of principal component analysis, the first two components accounted for more than 92.6% of total information. The first component explained 58.76% of the total variation. According to the drought tolerance index of Shastak, Ali Kazemi and Sang Tarom genotypes are recommended as tolerant genotypes having the highest yield in both environmental conditions and having high stress tolerance index.

In order to evaluate the drought tolerance of 19 barley genotypes using physiological traits, an experiment was carried out in randomized complete blocks with 3 replications under non-stress and terminal drought stress conditions at agricultural research station of Islamic Azad University, Ardabil branch in 2016. Non-stress plots were irrigated when available soil water reached to 60% using tensiometer measurements. In drought stress environment, plants were grown in rainfed condition and drought was imposed after flowering stage by a rain exclusion shelter. After exposure of plants to drought stress, Specific Leaf Area (SLA), Excised Leaf Water Loss (ELWL), leaf Relative Water Content (RWC), Stomatal Conductance (Gs), Chlorophyll Fluorescent (Fv/Fm) and Rate of Ground Cover (RGC) were measured in flag leaves of 10 randomly selected plants. Results of ANOVA showed that SLA, ELWL, RWC and GC affected by drought, however Fv/FM and stomatal conductance did not affected. Stress severity index was obtained as 0.45, indicating a moderate drought stress imposed to genotypes. G×E interaction was significant in all of the traits indicating the severity of the drought stress. In non-stress condition, genotype number 13 with 5040 kg/ha, had the highest grain yield. Under drought stress condition, genotypes number 13 and 15 with 2710 and 2550 kg/ha, had the highest grain yield respectively. Based on grain yield of the genotypes in both environments, genotypes number 13, 18(Bereke-54 check), 9, 4, 19 (Makouee check) and 15 had the highest stress tolerance index (STI). Under stress, genotypes number 15, 1, 18, 2, 3, 10, 13, 12 and 9 had the highest RWC, genotypes number 18, 13, 14 and 8 had the lowest ELWL, genotypes number 15, 9, 19, 18, 1, 13, 17, 4, 16, 5 and 12 had the highest Gs, genotypes number 9, 13, 8, 12, 14, 10, 11 and 15 had the highest RGC (early vigor), genotypes number 4, 3, 13, 15, 4, 12, 9, 17, 19, 1 and 11 had the highest SLA. In non-stress condition yield correlated only with RGC this trait was the only trait remained in final regression model and explained the 34.7% of grain yield variation. Under stress condition, yield positively correlated with RWC, SLA, Gs, RGC and negatively correlated with ELWL. In stepwise multiple regression analysis under drought stress condition, Gs, RGC and ELWL remained in final model with 0.489, 0.512 and 0.381 standard partial regression coefficients respectively(as direct effect). These three characters described 69.3% of grain yield variation. Cluster analysis using Euclidian distance by Ward’s method could successfully separate sensitive and tolerant genotypes. In this analysis, genotypes number 1, 4, 9, 12, 13, 15, 17, 18 and 19 were located in superior cluster, having higher Gs, RWC, SLA and lower Fv/FM. Finally genotype number 13 (the most high yielding genotype) had the second, third, fourth and sixth ranks in RGC, SLA, Fv/FM and Gs. The results of this experiment showed that RGC, having the highest correlation with yield and lower genotype × environment interaction can be consider as the most suitable indirect criteria for selection of drought tolerance in barley. Traits such as Gs, ELWL, RWC and SLA can be consider in the next priority, due to significant correlations with yield under drought stress.

Introduction Water stress is the most important cause of reduced wheat yield in semi-arid areas. In most regions under wheat cultivation, especially in regions with Mediterranean climates, wheat plants are exposed to various stresses during the seed filling. Seed filling often occurs when temperature rises and less water is available. Irrigated wheat in Khuzestan Province mainly faces end-season drought caused by limited water supply on the one hand and the reduced precipitation and competition by other crops for water on the other hand. Therefore, introducing wheat genotypes tolerant to end-season drought is of great importance for this Province. Materials and methodsThis research was conducted at the Agricultural and Natural Resources Research Center of Safiabad- Dezful in the crop years 2014-2015 and 2015-2016. Eight promising durum wheat lines in warm regions in Iran together with the Behrang cultivar were studied. The following two separate experiments were conducted using the randomized complete block design with two replications: (1) full irrigation until maturity and (2) application of end-season water deficit stress through irrigation cessation from the spike emergence stage to physiological maturity.Results and discussion Results indicated that the effect of year was significant under drought conditions but not significant in the absence of drought conditions. Moreover, the mutual effect of genotype and year were significant in the absence of drought but not significant under drought conditions. The mean two-year yield under conditions without water deficit stress was 4844 kg/ha, with the highest average seed yield (5101 kg/ha) belonging to line 1 and the lowest (4669 kg/la) to line 2. Although yield of line 3 under conditions without water deficit stress (5039 kg/ha) was a little lower than that of line 1, it enjoyed higher yield stability compared to the other lines because it had the average ranking of 2.5 and the standard deviation of 0.5. Furthermore, the mean two-year seed yield under end-season drought conditions was 3991 kg/ha, with the highest mean seed yield of 4332.5 kg/ha belonging to line 4 and the lowest (3710 kg/ha) to line 9. Under end-season drought conditions, line 4 had the largest seed yield and the highest yield stability in the two years of experiments with the average ranking of 2.5 and the standard deviation of 0.5.Principal component analysis (PCA) and the shape of the by plot were employed for the simultaneous study of the relationships between the genotypes and the quantitative drought tolerance indices. Results of the PCA showed that most of the variance in the data could be explained by the two components of PCA1 (the first component) and PCA2 (the second component) with 63% and 30%, respectively. In addition, among all of the calculated components, only PCA1 and PCA2 had eigenvalues higher than 1 (5.67 and 2.66, respectively). ConclusionThe strong positive correlation between seed yield in the two environments with and without water stress and the STI, MP, and GMP indices indicated that these indices had a high efficiency in selecting drought tolerant genotypes. Based on the results of PCA, genotypes 1 and 3 were selected as water deficit stress tolerant genotypes because of their high PCA1 and suitable PCA2 values and also due to their closeness to the important drought tolerance indices MP, GMP, K1STI, K2STI, and STI; whereas lines 6, 9, and 10 were introduced as water deficit stress sensitive genotypes because of their low PCA1 and PCA2 values and also due to their closeness to the SSI vector. Line 7 was between important drought tolerance indices and drought sensitivity indices and enjoyed relatively desirable drought tolerance, but the high estimated values of SSI and TOL for this cultivar indicated that it lacks suitable yield stability. Moreover, this cultivar is close to the Yp vector, which shows that drought tolerance in this genotype is due to its high yield in stress free environments.

Drought is one of the most destructive abiotic stresses worldwide that affects growth, development and final yield of crops. Reactions of thirteen rainfed spring 2-row barley genotypes and cultivars of cold areas of Iran to water stress were evaluated based on phenological, physiological and morphological traits. The experiment was carried out as factorial experiment based on a randomized complete blocks design with three replications under three irrigation treatments (normal irrigation and irrigation based on the 60% and 80% of available soil water depletion). The water stress was exerted two weeks before flowering. Results of mean comparisons showed that all the studied traits were reduced with increasing the level of water stress except branching of roots, root length and root length to plant height ratio. Taking all traits together, it is possible to identify two drought tolerant 71938 and 72566-1 genotypes and two Abidar and Dayton/Ranney cultivars which produced the highest yield under normal irrigation and both water stress conditions. Also, 71704 genotype could tolerate the first water stress level but not the second stress level. However, Denmark cultivar didn’t produce favorable yield in normal condition but was comparatively tolerant to both water stress levels. So, after doing competition tests under water stress in actual rainfed conditions in cold-dry and semi-dry land, these genotypes can be recommended for cultivation in these areas, and also can be used for improvement of drought tolerant genotypes in breeding programs.

The use of high yielding and resistant to drought stress cultivars in crops is one of the proper way to incorporation other water deficit management methods. This study in order to evaluate grain yield and morphological traits, an experiment was conducted with 100 genotypes of durum wheat which were planted based on lattice design with three replications under normal and drought stress conditions at the Agricultural Research Station in Varamin. The results showed that total dry matter have a highest positive direct effect on grain yield, whereas, grain yield filling period had the lowest effect and grain yield filling period via harvest index had the positive indirect effect on yield. Under stress condition, peduncle length had the highest positive direct effect on grain yield whereas, spike number, plant length, total dry matter, and date from germination to maturity had negative and direct effect. Factor analysis explained 80.5 and 83.3 of the total variation under normal and drought conditions, respectively. To estimate better grain yield, drought tolerance indices were determined and genotypes 3, 45 and 21 were identified with the lowest value of the indices MP, GMP and STI that were for drought condition while genotypes 45, 21, 71, 34, 78 had the highest value of the mentioned indices and were suitable for both conditions. Cluster analysis grouped genotypes into four clusters in both conditions which confirmed the results of stepwise regression as well as path analysis that could separate genotypes with high grain yield from others as well as traits affecting yield compared to other traits.

IntroductionMajor cultivated cotton regions of Iran are located in dry and semiarid climates, therefore water deficiency or drought stress is inseparable part of cotton production systems in these regions. So identification and introduction of drought tolerant cotton genotypes is crucial. showed that water stress decreased plant growth rate, leaf area and finally photosynthesis in cotton. In addition plant height reduction is a primary effect of water stress. According to results, net photosynthesis, stomatal conductance and transpiration decreased simultaneously with an increase in drought stress intensity.
Physiologic traits monitoring were notified as a proper gadget for selection and improvement of germplasm. Whereas investigation of many genotypes in field conditions under drought stress is difficult and it is not accurate enough, also good correlation has observed between the results of drought tolerance at seedling stage and field experiments, therefore this research has tried to evaluate some of the morphologic traits in cotton genotypes at seedling stage under drought stress and none stress conditions.
Materials and Methods22 cotton cultivars were grown under none water stress (field capacity) and drought stress conditions(-1MPa) using a factorial arrangement of treatments based on randomized completely design with three replications at College of Agriculture, Ferdowsi University of Mashhad in 2011. Then each genotype (10 seed) was sown at a pot (1.5 l-1). At two true leaf stages, pots were tinned to one seedling. Soil moisture content was kept up to two true leaf stages at field capacity and at the end of experiment, it was conserved about -1MPa using weight method.
The measured parameters were:Plant height, leaf area, dry weight of leaf, stem, root and whole plant and also decreasing percent of each parameter under stress in comparison with control in any genotype was determined at the end of experiment. Stomatal resistance and leaf temperature were measured with leaf porometer set (model Decagon Devices, Inc) on three leaf stage of cotton seedling. Relative water content (RWC) of leaf was also measured. Variance analysis, Comparison of trait means and correlation between traits were carried out using SAS and Excel and least significant difference (LSD).
Results and DiscussionInteraction between water deficiency stress and cotton cultivars were significant (P

Water deficit always has been considered as one of the most limiting factor to agricultural production in Iran, as the country is located in the arid and semi-arid zone. This study aimed to evaluate genetic variation among wheat germplasm for drought tolerance and to determine the possible application of 13C isotope discrimination method in identifying wheat genotypes with higher WUE. A number of 160 wheat lines and cultivars with varying level of drought tolerance were examined in observation plots under augmented randomized complete block design along with 4 check cultivars repeated in all 10 blocks. The experiment was performed at Dryland Agricultural Research Station in Maragheh under rainfed conditions during 2009-10 growing season. Data analysis revealed significant differences among the evaluated genotypes for yield under dryland conditions. Our finding suggested that late-mature genotypes have shorter height and lower harvest index, lower thousand kernel weight, which resulted in less yield under dryland conditions. The findings lead to the identification of 22 superior lines with higher yield and desired agronomic traits compared to the check cultivars. Calculation of linear correlation showed significant negative correlation between Δ and wheat grain yield. Under dryland conditions, genotypes with higher yield had lower 13C isotope discrimination. Grain yield showed a significant and negative correlation with 13C discrimination in wheat grown under dryland conditions. This finding suggest that using 13C discrimination to identify wheat genotypes with higher WUE will be able to yield more under dryland conditions.

The effects of drought stress on yield, yield components and some of drought resistance and sensitivity indices, such as sensitivity stress index (SSI), tolerance index (TOL), means productivity (MP), geometric means productivity (GMP) and stress tolerance index (STI) were evaluated on ten lentil genotypes with an experiment at agricultural and natural research station of Ardabil. The experiment was carried out under dry-land (drought stress) and irrigated (non-drought stress) conditions in a randomized complete block design with three replications. The results of combined variance analysis showed a high diversity in all of traits among studied genotypes. Based on mean comparisons of traits, the native Gazvin, 225-12-C and 418-22-22,15 genotypes had the highest values of grain yield in both of dry-land and irrigated condition. The results of correlation among the traits studied showed that the number of pod per plant, plant, biological yield and harvest index had the highest positive and significant correlation with grain yield. Correlation among the days to 50 percent of flowering and days to maturity with grain yield was negative and significant, showing that late flowering and late maturity lentil genotypes had lower grain yield. Among geometric means productivity (GMP) and stress tolerance index (STI) with grain yield in both of dry-land and irrigated condition were observed the positive and significant correlation, so can be indentify those as the best optimum drought resistance indices and used for selection of lentil genotypes with high potential yields in both dry-land (drought stress) and irrigated (non-drought stress) conditions. In this experiment the native Gazvin, 225 12-C and 418-22-22,15 genotypes compared with other genotypes along with high drought tolerance, had higher grain yield in both dry-land and irrigated conditions.

Rice plant requires abundant water during its growth cycle and usually faced with water deficit. Drought stress alters the allocation assimilate, root and shoot growth during the vegetative period and also lower tillering, death tillers, lower plant height and flowering delay. the aim of this study was to screen different Iranian genotypes and some lines from IRRI with identify the morphology and physiology traits such as drought tolerance mechanisms in order to select drought tolerant genotypes. Treatments (56 rice genotypes) were arranged in completely randomized block design in two growth conditions including full irrigation and drought stress at seedling stage in Rice Research Institute of Iran, Deputy of Mazandaran (Amol) in 2013. Some morphological and physiological traits including leaf relative water content (RWC), SPAD value, leaf color (LC), plant height, leaf area and number per plant, root and shoot dry weights, root length, Membrane electrolyte leakage (MEL) and pH were measured. Results showed that all traits in both well watered and stress conditions as well as genotype× environment (G*E) interaction were significantly different. In comparison with the other characters, RWC (17.3%), root dry weight (28.2%) and shoot dry weight (21.9%) were reduced while MEL (86%) was increased in stress conditions. Correlation results showed that root and shoot dry weights were significantly correlated with plant total dry weight in stress conditions. Genotypes with better performance in stress conditions were selected as drought tolerant genotypes. These genotypes are including Tarom-Mahalli, Tarom-Deylamani, Neda, Fajr, Shafagh, Tabesh, Koohsar, Gohar, Hamr, Anboori-Ghermez, Doroudzan, Zayanderoud and Firuzan from Iranian local and improved varieties as well as seven improved lines from IRRI.

The aim of this study was to determine the drought tolerance control loci in growth stage in bread wheat. In this regards 99 doubled haploid lines with their parents were evaluated in a randomized complete block design with three replications in two drought stress levels. Genotypes mean square for all traits in two environments was significant. Thirty three SSR markers and 24 TRAP markers which was polymorphism in the parents were tested on doubled haploid lines. QTL analysis was performed with single marker analysis. In non stress conditions five QTLs on chromosomes 1B, 1A, 3A, 5A and 7A and in stress conditions two QTLs on chromosomes 2D and 7A were identified for plant height, which overall were explained 36.35 and 13.49 percent of this trait variation in the non stress and stress environments respectively. For plant fresh weight six QTLs were identified in non stress conditions on chromosomes 1A, 1B, 2A, 5D, 1D and 5B and in stress conditions five QTLs on chromosomes 1A, 4A, 2B, 5A and 7A. These QTLs were explained 36.79 and 28.06 percent of this trait variation in non stress and stress environments respectively. For plant dry weight five QTLs were identified in non stress conditions on chromosomes 1B, 5D, 4A, 5A and 7A and two QTLs in stress conditions on chromosomes 1A and 7A. These QTLs were explained 28.57 and 13.65 percent of this trait variation in non stress and stress environments respectively. For water relative content for QTLs were identified in non stress conditions on chromosomes 1A, 4A, 5A and 6B and three QTLs in stress condition on chromosomes 7A, 5A and 4A. These QTLs were explained 26.23 and 25.87 percent of this trait variation in non stress and stress environments respectively.

To investigate drought stress effects on grain yield and its component in chickpea genotypes and its relation with physiological characteristics, nineteen chickpea genotypes were evaluated in field and pot experiments at the Faculty of Agriculture, University of Kurdistan, Sanandaj, Iran, in 2010-11 cropping season. Field experiment was carried out as split plot arrangement in randomized complete blocks design (RCBD) with three replications. Irrigation and rainfed conditions were assigned to main plots and chickpea genotypes were randomized in subplots. Grain yield, some yield components and drought resistance and susceptible indices were measured and recorded. Pot experiment was conducted as factorial arrangement using RCBD with two factors including irrigation treatments (irrigation at -3 (control) and -12 bar (stress) of soil water potential) and 19 chickpea genotypes as second factor with three replications. In this experiment, stomatal conductance at the vegetative stage and polyphenol oxidase activity at the vegetative and reproductive stages were studied. Chickpea genotypes divided in high and low yield potential and drought tolerant and susceptible genotypes based on seed yield under drought and control conditions. Results showed that drought stress reduced pod and grain per square meter by 43% and 44%, respectively and caused 43% reduction of grain yield, however, it did not have significant effect on 100 grain weight. In pot experiment, drought stress reduced stomatal conductance by 78% and drought tolerant genotypes had 33% higher stomatal conductance in comparison to drought susceptible genotypes. There were highly significant positive correlation (r = 0.52**) between polyphenol oxidase activity and stomatal conductance. It can be conclude that polyphenol oxidase activity and stomatal conductance would be useful physiological traits for improvement of drought tolerant genotypes in chickpea breeding programs.

In order to study effect of water deficit on growth، yield and yield components on three spring barley (Hordeum Vulgare L.) genotypes، an experiment was conducted in Ardabil Agricultural Research Station، Iran in 2003-2004. The experiment was split plot as complete block design with three replications. Water treatment including: Well watered (Normal)، No irrigation in all growth stage (stressed) and Water stress induction after anthesis were arranged in main plots and three barley genotypes: LB-IRAN، N-81-7 and N-81-14 in sub plots. In all water treatments dry matter accumulation trend was sigmoid figure، however the value had variation under water treatment affected. Maximum and minimum LAI obtained from well watered and stressed in all growth stage treatment respectively. LB-IRAN genotype had the highest values of growth parameters. There was no significantly different on tillage per plant and grain number per ear between non- irrigated and exposing of water stress after anthesis، but 1000- grain weight of them was significantly affected. Final grain yield of non-irrigated treatment decreased compared to well watered and water stress exposing after anthesis (63. 7 and 17. 2 percent، respectively). Maximum grain number per ear obtained from LB-IRAN and N-81-14. The highest 1000- grain weight was belonging to LB-IRAN and N-81-7 genotypes. The grain yield in LB-IRAN genotype (2034 kg. ha-1) was higher than others genotypes. According to Fernandez tolerance index، N-81-14 genotype had high yield stability.

Drought stress is the most important factor that reduces yield in crops including chickpea and causes some changes in seed composition. This study was performed in order to evaluate the effects of drought stress and starter nitrogen fertilizer on four cultivars of chickpea. Experiment was performed in a split-factorial using randomized complete block design with three replications. Drought stress treatment stand as main plots in three levels consist of no drought stress (complete irrigation), moderate drought stress (irrigation at planting and early flowering) and severe drought stress (no irrigation). Nitrogen fertilizer in two levels (0 and 25kg N/ha) and cultivar treatment (four cultivars Azad, Bivanij, Hashem and ILC482) allocated in sub plots. The results showed that effects of drought stress treatments were significant on proline content, amount of soluble sugar, membrane stability index (MSI), relative water content (RWC), chlorophyll-a, chlorophyll-b, total chlorophyll and excised-leaf water loss (RWL). Application of nitrogen fertilizer treatment only significantly increased membrane stability index (MSI). Effect of cultivar treatment was significant on proline, soluble sugar, membrane stability index (MSI), chlorophyll-a, total chlorophyll, relative water content (RWC) and excised-leaf water loss (RWL). Results showed that with increase of drought stress level amounts of chlorophyll-a, chlorophyll-b, total chlorophyll, relative water content (RWC) and membrane stability index (MSI) decreased while proline content and soluble sugar increased by three and two-fold compared to control, respectively. This osmoprotectant accumulation probably explains increase in plant tolerance to drought stress.

In order to evaluation of genetic variation in segregating population، 374 F3-Plants (lines) were planted in augmented design with four check varieties (Azar-2، 87-Zhong291، Kharchia and Superseri≠2). These check varieties planted in Randomly Complete Block Design with 7 replications. For germination of seeds، the farm was irrigated just one time. During and at the end of growth season we measured some agronomic and morphological characters such as seed yield and it’s component، plant height، day to flowering، peduncle length، awn length، harvest index، biological yield and etc. After adjusting the data، some statistical indices were calculated. The results of analysis showed the diversity between experimental materials. Standard deviation of plant height was the highest and for harvest index was less. In order to evaluation of correlation between traits، Pearson correlations were calculated that the importance of peduncle length was cleared. But awn length and spike weight didn’t show any correlation. For deletion of non-efficient or less-efficient traits on seed yield، stepwise regression was used and concluded that 98% of variation between genotypes were caused by three characters (spike weight، harvest index and biological yield). For decreasing of variables and better conclusion، Factor analysis was used that four factors were identified. Finally، because of high variation in analyzed population and high potential of the population for line selection، to reaching maximum purity، management of the population was recommended.

Twenty hulless barley genotypes were assessed by 85 RAPD markers having 10 bps. Thirty five markers (41%) had suitable polymorphism using 227 amplified markers. The average number of amplified segments was 6.48. The size of amplified products varied from 400 to 2700 kb. Primer 540 had the highest and primers 498, 559, 577 and MT9 had the lowest amplified segments. Jacard similarity coefficient ranged from 0.3770 to 0.8. The highest similarity was observed between genotypes no. 15 and 16 (0.8) and also between no. 2 and 3 (0.759). The cluster analysis based on Jacard similarity and complete linkage method classified hulless barley genotypes into three groups. The results of the cluster analysis corresponded with the pedigree of the genotypes and the genotypes with the similar pedigree were grouped mostly in one cluster. This suggests the efficiency of RAPD markers in detecting genetic diversity of hulless barley germplasm. Principal coordinates analysis showed that five coordinates accounted for only 42.58% of variation which indicated the proper distribution of markers in the hulless barley genome because of relatively low percentage determined by the five first coordinates. Diversity of hulless barley genotypes was also evaluated by 25 agronomic characters using the range of every trait as a percent of mean. The results showed the existence of considerable variability among the genotypes for most of characters. Analysis of regression showed that 20, 19, 18, 14, 11 and 10 markers were informative for spike length, number of grains per plant, grain yield per plant, number of effective tillers, heading date and 1000 grain weight, respectively. From 18 informative markers for grain yield eight were similar with the markers informative for the number of grains per plant which suggests that from molecular view point this character could be regarded as the most important component of grain yield per plant in hulless barley.