Biochemical and physiological traits are affected by environmental stresses and therefore the breeding of these traits will play an effective role in stress tolerance. In this study, hybrids of five S₇ lines of maize in a 5 × 5 half-diallel design were investigated in order to study the combining ability of biochemical and physiological traits of maize at the Research Farm of Graduate University of Advanced Technology, Kerman, Iran during the 2017-18 crop year based on randomized complete block design with three replications. The results of analysis of variance by fourth Griffing's method showed that the general (GCA) and specific (SCA) combining ability variances were significant for protein, proline, sugar content, carotenoid, chlorophyll a, chlorophyll b and total chlorophyll traits. Therefore, the role of additive and non-additive effects was identified in controlling these traits. Protein, proline, chlorophyll a and total chlorophyll traits were more controlled by additive effects, whereas the carotenoid trait was more controlled by non-additive effects and the role of additive and non-additive effects in controlling other traits was almost equal. The KSC704-S7-11 line showed positive and significant general combining ability for most of the studied traits, suggesting this line can be used in breeding programs to improve and increase stress tolerance. In addition, P1 × P3 and P4 × P5 crosses showed the most positive and significant specific combining ability for proline, chlorophyll a, total chlorophyll and carotenoid traits; thus they can be considered as the best hybrids to improve and increase stress tolerance in corn.

In order to estimation genotypic correlation and heritability of some faba bean traits, 26 faba bean genotypes were evaluated in a randomized complete block design with three replications during 2014-16 growing seasons in Agricultural Research Sation of Borujerd located in Lorestan province, Iran. The restricted maximum likelihood (REML) was used to estimate the genotypic and phenotypic correlations, broad sence heritability and genetic gain. Analysis of variance based on least squares and REML indicated significant effect of genotype on days to maturity, plant height, hundred seed weight, pod length and dry seed yield. Genotype×year interactions were significant on all of the traits except of pod length. Borujerd cultivar (G26) and G20 had the highest dry seed yield in both of years. REML results indicated a significant positive genetic correlation between dry seed yield and biological yield and plant height. Also, there were a significant negative phenotypic correlation between dry seed yield and days to maturity, and significant positive phenotypic correlation between dry seed yield and plant height, biological yield and harvest index. So, the selection of early maturing genotypes with a higher yield is achievable and selection can be done to improve the performance of dry seed yield. Cluster analysis indicated variability among genotypes. According to values of broad sence heritability and genetic gain for plant height and high genetic correlation of this trait and dry seed yield; plant height can be used as a suitable trait for improving dry seed yield by selection.

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 identify QTLs controlling agronomically traits, landrace Tarom and rice Tarom mutant were crossed. SSR, ISSR, iPBS and IRAP markers were amplified in 250 F₂ individuals to prepare the linkage map. Number of tillers, 100 grain weight, number of filled grains, number of unfilled grains, plant height, panicle length, number of branches, stem diameter, grain length, grain width, grain shape, straw weight, days to maturity, flag leaf length and flag leaf width were measured for 250 individuals. The linkage map covered 970.9 cM of rice genome. The distance between two adjacent markers was calculated to be 12.77 cM. Based on the results, a total of 13 QTLs were identified for the evaluated traits. For all studied traits, alleles transferred from the parents to the QTLs detected increased grain yield. Most QTLs were detected for days to flowering. Three QTLs were located on chromosomes 10 and 4 (two QTLs) for days to flowering. qLDF-4a and qLDF-4b had a negative additive effect and the parent alleles of the mutant landrace Tarom reduced the number of days to flowering. These QTLs explained 11.6% of the phenotypic variance. Since the population under study was derived from a cross between landrace and mutant Tarom cultivars and the resulting population varied only in the mutated genes; so, the QTLs detected in this study were more accurate in location and expression levels, and after validation of them, they could be recommended for marker assistant selection breeding programs.

In order to determine the heritability and genetic parameters of some agronomic traits in barely (Hordeum vulgare L.) cultivars, a seven-parent half diallel (F₁ crosses + parents) was conducted in the non-stress and salt stress (8 and 12 ds m^-1) conditions in a randomized complete block design with three replications. Genetic analysis was performed by Hayman’s method and Griffing’s fixed model, method 2. The slope of linear regression of W_r on V_r were significantly higher than 0 and had not significant difference with 1 indicating the additive-dominant model was satisfied in all cases. The narrow-sense heritability of traits was medium to high (0.4-0.8) but their broad-sense heritability was estimated relatively high (0.7-0.9). Results of regression graphs showed that Afzal parent had the most dominant allele. The significance of “a” component in most of the studied traits indicated the presence of the additive effects in controlling of traits. The significance of “b” component in most of the studied traits indicated the presence of the dominance effects in controlling of traits. The proportion of positive and negative genes was lower than 0.25 in all of the traits (except for grain weight per spike in 12 ds m^-1 salinity), indicating the presence of asymmetry in the distribution of the positive and negative alleles in the parents. Based on general combining ability effects, it was concluded that under salinity, cultivar “Kavir” had favorable alleles in plant height, grain weight per spike and 100 grain weight traits and can be used as a general parent in breeding programs. Estimates of high broad-sense heritability and narrow-sense heritability in most traits indicated that these genetic materials were promising for breeding under normal and salinity stress conditions.

There are different methods for study the genotype × environment interactions and determining stable genotypes such as parametric, non-parametric and multivariate methods. In this research, 19 selective genotypes from advanced trials of durum wheat at 2011-2012 agronomic year, have been cultivated with Dehdasht check cultivar for three growing years (2012-2015) in five locations (including Gachsaran, Gonbad, Khorramabad, Moghan and Ilam) in a randomized complete block design with four replications in each location. Combined analysis of variance indicated significant effects of genotype, environment and interactions of genotype × environment. In parametric uni-variate methods, genotypes 7, 12, 18 and 20 were determined as stable genotypes. In non-parametric uni-variate methods, genotypes 2, 7, 12, 13, 18, 19 and 20 had the lowest genotype × environment interaction and they were determined as stable genotypes. In AMMI method, genotypes 2, 7, 12, 19 and 20 had the lowest rank in different environments and highest grain yield, and these genotypes seems more stable genotypes. It can be concluded that genotypes 7, 12, 18 and 20 could be considered as promising genotypes and candidate for introducing new durum cultivar.

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.

Plant breeding researches is based on genetic diversity and evaluation of genetic diversity is also one of the most important steps in introduction of new cultivars. In this study, genetic diversity of 25 grass pea genotypes was studied based on randomized complete block design with three replicates in Khorramabad (Iran). Analysis of variance showed significant differences among genotypes for most of traits. Mean comparison showed that genotype IF1312 with the highest grain yield and genotypes IF1332 and IF471 with the highest dry and fresh forage yield had the best yield. Principal component analysis showed that the first 3 factors explained 62.64% of total variance. Based on cluster analysis, genotypes IF1307, IF1872 and IF471 with the highest grain and forage yield are belonged to one cluster. REML method was used to estimate genetic correlation and heritability of different traits. The highest amount of heritability (0.87) was estimated for number of immature grains and the least heritability (0.10) was estimated for total dry weight. Grain yield had a high and positive genetic correlation with forage yield, and biomass, percentage of leaf and dry forage yield also had a high and positive genetic correlation with fresh forage yield. Totally, genotype IF1307 had the best performance for most of traits compared to the other genotypes and had an acceptable forage yield among genotypes.