In the present study, in order to evaluate the drought tolerance indices and their relationship with ISSR markers, 12 rapeseed genotypes were studied using a factorial experiment based on completely randomized block design under the three irrigation treatments (control and irrigation after drainage of 60 and 85% moisture content) in the greenhouse of Mohaghegh Ardabili University, Iran. Drought tolerance genotypes were evaluated by quantitative indices including MP, GMP, SSI, STI and TOL. Cultivars in all five of indices at two levels of stress exhibited significant differences. Regarding the results of the mean comparison at both levels of stress, SLMO46 was identified as the most resistant cultivar with the highest amount of MP and STI, and Karun was the most sensitive one with the highest amount of SSI index. According to the results of factor analysis, in the first level of stress, Sarigol32 and Karun were sensitive, and in the second level of stress, Talaye and Sarigol32 were sensitive as well. SLMO46 was known to be resistant to stress in both levels of stress. Phenotypic correlation of grain yield under stress and non-stress conditions was investigated in two levels of stress with 5 drought indices. In first level of stress condition, grain yield had a positive and significant correlation with mean productivity, geometric mean of productivity and stress tolerance index. In the second level of stress condition, the same correlation was observed with the difference that there was no significant correlation between drought tolerance and tolerance indices. Canonical correlation analysis was performed between drought indices and molecular markers. Five ISSR primers (5, 9, 11, 14 and 19) with the highest polymorphic percentages were used for calculation using the first factor coefficients. ISSR-PCR was used to identify some of the molecular markers associated with drought tolerance indices. A total of 106 clear and score-able loci were amplified by 18 ISSR primers, of which 60 bands (56.6%) were polymorphic. Finally, according to the results, these markers can be used in rapeseed breeding programs for drought tolerance.

Mutagenesis has been one of the important sources of genetic diversity and Plant mutants can be important bio-resources for crop breeding and functional genomics studies. Breeding conventional methods for generating of genetic variability are of low efficiency. We showed that treatment of seeds of rice(Hashemi cultivar) with 0.8% EMS for 8 h caused visible phenotypic variations on M2 rice mutant genotypes including flowering date, plant height, number of fertile tiller, panicle length, number of filled and unfilled grains per panicle, grain width and length, 100 grain weight and grain yield. The phenotypic variation coefficients of most traits found to be more than the genetic variation coefficients. The number of filled grains per panicle and seed length had the highest and lowest general heritability, respectivly. The seed yield had also high heritability. Analysis of correlation between different characteristics in the mutant genotypes showed that the number of fertile tillers and the number of unfilled grains per panicle had positive correlation with yield. Also, grain yield exhibited positive and significant correlation with panicle length, number of tillers and number of filled grains at genotypic level. In multiple regression analysis by stepwise method, number of tillers, number of filled grains per panicle, 100-grain weight, and grain width entered into the model, respectively, that explained 96 percent of grain yield variations. Results of grain yield and its components path coefficient analysis showed that the number of tiller had the highest direct effect (0.77) through than other traits on grain yield and, therefore it can be considered as major trait in grain yield improvement in rice. Also, based on results of this research and by using optimal selection index, mutant genotypes EM 18-17-5 and EM 15-14-1 were selected as superior mutant genotypes. This mutant population is expected to be serves as a genetical resource for understanding rice biology as well as for use in genetic improvement of quantitative traits.

In order to determine the most effective indices for quantifying drought tolerance and identify genotypes that are tolerant to water stress in bread wheat, 50 bread wheat genotypes were compared in a randomized complete block design with three replications under both the non-stress dry farming with two complementary irrigation and the water stress dry farming conditions in Khorramabad, Iran. Analysis of variance showed that there was a significant difference among the genotypes in terms of all of the traits except the number of spike per area. In this study, eight indices including: Stress Tolerance Index (STI), Geometric Mean Productivity (GMP), Mean Productivity (MP), Yield Index (YI), Harmonic Mean (HM), Yield Stability Index (YSI), Stress Susceptibility Index (SSI), and Tolerance index (TOL) were calculated by using of seed yield of the genotypes under both conditions. Indices that selection based on them will improve the yield in both conditions, are considered as suitable index. STI, GMP, MP and HM were introduced as suitable index for drought resistance selection. Genotypes Shiroodi and S-90-5 were determined as the most appropriate based on 3D plot. Based on positive correlation between water stress resistance indices and yield under stress and non-stress environments, STI and GMP were the best indices. By using the Biplot method, Shiroodi, S-90-5 and Oroum genotypes were considered as high yielding potential genotypes under the both conditions. According to the results of cluster analysis, genotypes were classified into three groups based on drought tolerance indices. Graphical analysis of genotypes also showed that genotypes Shiroodi and S-90-5 were more profitable than others under both drought stress and non-drought stress conditions. These genotypes could also be used as parents caring desirable genes in the crossing programs and selection of tolerate genotypes.

The genotype × environment interaction is a major challenge in the study of quantitative characters because it reduces yield stability in different environments and also it complicates the interpretation of genetic experiments and makes predictions difficult. In this regard to analysis of genotype × environment interaction and determine the yield stability of winter rapeseed genotypes in cold and mild cold regions of the country, 9 lines and 4 cultivars were evaluated in a randomized complete block design with three replications in six experimental field stations (Isfahan, Hamedan, Karaj, Kermanshah, Khoy and Zarghan) during 2015–2017 growing seasons. Results of combined analysis of variance indicated that the effects of environments, genotypes and genotype × environment interaction were significant, suggesting that the genotypes responded differently in the studied environment conditions. So, there was the possibility of stability analysis. The Nafis cultivar and BAL-92-1 line with seed yields 4086 and 3829 kg.h^-1, respectively, were better than overall mean and had lower ranks and rank variance than others. According to the results of stability analysis using Eberhart and Russel method, the BAL-92-1 line with higher seed yield than overall mean and regression coefficient equal one (bi=1) was identified as the genotype with high general stability for all regions. Based on the simultaneous selection method for yield and stability (YSi), the lines of HW-92-1, BAL-92-1, HW-92-1 and Nafis cultivar with the lowest values were stable, whereas lines BAL-92-4, HW-92-2, HW-92-3 and Ahmadi cultivar with highest values were unstable. Also, based on the SIIG index, the lines of HW-92-1, BAL-92-1, BAL-92-6, BAL-92-11 and Nafis cultivar with having high SIIG value as well as higher seed yield that total average were recognized as superior genotypes from the point of stability and seed yield. Finally, BAL-92-1 line with high yield and broad adaptability was selected as superior line for supplementary studies to introduce the new commercial cultivar in cold and mild cold regions of Iran.

Additive main effect and multiplicative interaction (AMMI) and best linear unbiased prediction (BLUP) are two methods for analyzing multi-environment trials (MET). In this study, seven selected rice lines were evaluated along with two check varieties based on randomized complete block design in Tonekabon, Amol and Sari (Iran) in three growing seasons of 2011-14. To quantify the genotypic stability, the best linear unbiased predictions of the genotype by environment interactions (GEI) were estimated, and singular value decomposition (SVD), which is the basis of AMMI analysis, was performed on the resulting matrix. The likelihood ratio test (LRT) showed that the effect of GEI was significant on grain yield, number of tillers, thousand grains weight and panicle length. Therefore, due to the significant interaction of genotype by environment, BLUP analysis can be performed on this data. The biplot of first principal component (PC1) of the environment versus nominal yield showed that genotypes 7 ([IR 67015-22-6-2-(A37632) × (Amol3 × Ramzanalitarom)]39), 6 (IR67015-22-6-2-(A37632) × (Amol3 × Ramzanalitarom)]126) and 2 ([IR64669-153-2-3 - (A8948) × (4Surinam Deylamani)]2), due to the lowest scores of the PC1, had a small share in the GEI and had more grain yield stability. The biplot of grain yield versus WAASB, placed genotypes in four regions, so that genotypes in the fourth region, including genotypes 6, 7, 8 (Line 843, check variety), and 9 (Shirodi, check variety), were due to large value of response variable (high grain yield) and high stability (low values of WAASB) were very productive and had extensive stability. Identification of genotypes with weighted average of WAASB and response variable (WAASBY) criteria showed that genotypes 6 and 7 were high yields and stable. Based on the multi-trait stability index (MTSI), G6 was also selected as the best genotype in terms of grain yield, evaluated traits and stability of each trait. Totally, genotype 6 was stable and superior based on the results of all methods.