genetic variance

Cucumber (Cucumis sativus L.) is an annual plant in the Cucurbitaceae family, which has 90 genera and 750 species. Iran, with an under-cultivation area of 89,632 hectares and a production rate of 1,804,184 tons of cucumbers, yield of 201,289 tons per hectare, and it is the third largest cucumber producing country in the world in terms of production. Use of fruits of these vegetable is different depending on the country and the consumer's taste and demand, and it is cultivated for fresh consumption as well as processing (pickled vegetables or cucumbers). The utilization of local genotypes or unmodified native reserves for production has led to very low yield of cucumbers in some countries of the world. The general objectives of cucumber breeding are resistance to diseases and pests, fruit quality and yield increase. Considering the history of cultivation of this product in Iran and due to the large under-cultivation areas of cucumber in the country, little breeding research has been done on this product and the country's required seeds are supplied annually through imports. Therefore, practical and applied research on the breeding of cucumber plant seems necessary. The present study was conducted to evaluate 27 cucumber plant lines using factor analysis and cluster analysis as a tool to identify superior genotypes and more effective traits.

This study was carried out in the research greenhouse of Department of Horticultural Sciences, Faculty of Agricultural Sciences, University of Guilan, with a longitude of 49 degrees and 36 minutes east and latitude 37 degrees and 16 minutes north with a height of 7 meters from the level of the open sea in February 2021. Overall, 35 cucumber inbred lines, available in the Germplasm Bank, University of Guilan, were selected and on completely randomized design, in three separate rows, and with three replications. A code was assigned to each of the lines in order to facilitate the naming of lines and easier evaluation. In the winter of 2019, the desired genotypes were first planted in the seedling tray and kept there until the second true leaves were observed. Then they were transferred to the greenhouse in the form of a completely randomized design with 27 lines of inbred cucumbers, in three separate rows with 3 replications and 3 observations. The length of the plant breeding period continued until the economic fruiting of the plant. During the growing season, various traits were checked and recorded according to the national guidelines for tests of differentiation, uniformity and stability in cucumber prepared by the Research Institute of Registration and Certification of Seeds and Seedlings. These traits are the Fruit diameter (mm), Fruit length (mm), Fruit number, Weight of single fruit (g), Total fruit weight (g), Number of female flowers in 15 nodes, Number of female flowers per node, Width of the end of the terminal leaf(cm), Length of the end of the terminal leaf(cm), Number of lateral branches in 15 nodes, Length of 15 internodes (cm).

Genetic diversity in plant genotypes is essential for a successful breeding program. Understanding the degree of variability in plant species is of importance because it provides the basis for selection. The results of variance analysis show that there is a highly significant variation between the studied lines at the level of 1%. The significant difference observed between genotypes for all traits indicates the existence of inherent genetic variation among genotypes.The evaluation results show that the average fruit weight trait varied from 1371.7 grams (L57) to 157.71 grams (L35) among the examined lines. Furthermore, genotype L57 (117.56 grams) had the highest statistical position in terms of single fruit weight. The results of the mean comparison table showed that L34 line had the highest fruit length values (161.84 mm) and L49 line had the highest fruit diameter values (39.83 mm). Moreover, L55 and L34 lines had the lowest values of fruit length (92.46 mm) and diameter (24.61 mm), respectively. The leaf area variable varied from 426.52 cm2 (L57) to 204.24 cm2 (L31) among the studied lines. The results of chlorophyll index traits investigation and total soluble solids showed that L51 line had the highest values in both traits.The results of statistical analyses pertaining to genotypic and phenotypic variance, as well as general heritability, revealed that the trait with the highest heritability, at 99.44%, was fruit weight. With the exception of five traits-length of 15 primary internodes, leaf surface, length and width of the terminal leaf, and single fruit weight-whose heritability values were 87.35%, 73.83%, 63.59%, 61.27%, and 26.23%, respectively, the heritability exceeded 90% for the remaining traits. These findings indicate that most of the traits examined exhibited high heritability, suggesting they were less influenced by environmental factors. Factor analysis, an essential multivariate technique, was employed to explore trait relationships and assess the genetic diversity among genotypes. The results of factor analysis for 27 evaluated cucumber genotypes show that eight factors were identified. They were 23.52, 12.63, 11.81, 9.95, 8.6, 7.34, 6.27, 4.21 percent. in total explained 88% of the total diversity of traits in the studied population. In total, they justified 88% diversity of total traits in the studied population. The results of the cluster analysis placed the studied genotypes in four different groups based on the mean of traits. To ensure the cut-point in the dendrogram and to determine the actual number of groups, the discrimination function analysis method was used. The results of discrimination function analysis showed that the success of cluster analysis in grouping genotypes was 100%. Since the genotypes in each of the clusters have a greater genetic affinity with the genotypes in the same cluster and, conversely, a greater genetic distance with the genotypes in different clusters, hybridization can be done among the genotypes in different clusters according to the value of traits average for each cluster for more productivity of phenomena such as heterosis and transgressive segregation. On this basis, it seems that it is possible to produce hybrids that are superior to their parents in terms of various traits by hybridization between the genotypes in the first and second clusters with the genotypes in the third and fourth clusters.

According to the results obtained from this study, L57 and L54 genotypes had higher values than the rest of the genotypes in terms of fruit number and total fruit weight. Also, according to the results of cluster analysis, L57 line had higher total mean values in traits of total fruit weight, single fruit weight, diameter of the tail of the fruit, fruit, kernel diameter, fresh and dry weight of leaves and leaf area. In this study, the genotypes of the second and third groups in the fruit number trait, and the genotypes of the first and third groups in the fruit weight trait, due to having the maximum difference, were found suitable for use in crosses in order to create more diversity. In general, the results of this research showed that there was a suitable diversity among the studied lines in terms of all measured traits. In addition to the fact that the results obtained from this research can be used in future breeding programs, the results of multivariate statistical methods also show solutions for the scientific crossing of genotypes in future research. So that the genotypes placed in different groups in cluster analysis (Group 1: L57, Group 2: L54, L52, L47, L32, L49, and L27, Group 3: L43 and L35, Group 4: L59, L53, L51, L34, L26, L55, L25, L39, L31, L30, L33, L28, L29, L36, L24, L44, L22, and L20) and had superior characteristics in terms of different components, can be crossed together to create recombinant genotypes.

In this study, the effect of dietary corn replacement with oak acorn on the expression of pancreatic chymotrypsin gene in broilers was investigated. The use of oak acorn in poultry feed can reduce feed intake, nutrient digestion and poultry performance by binding to dietary proteins and digestive enzymes. Therefore, the aim of this study was to evaluate the expression of pancreatic chymotrypsin gene in broilers fed with different levels of oak acorn. For this purpose, broilers were fed with three treatments (control, 15% and 20% oak flour) from 1 to 42 days of age. At 21 and 42 days of age, pancreatic tissue was isolated and weighed from 36 chickens (6 from each treatment at each age) after slaughter and then total RNA was extracted. To evaluate gene expression, chymotrypsin gene expression was compared with beta-actin gene as reference gene. To analysis of gene expression data, REST V2.0.13 software and SAS 9.1 software were used. At 21 days of age, no significant difference was observed in relative weight of pancreas between different treatments (p> 0.05), while at 42 days of age, relative weight of pancreas in 20% oak acorn treatment was significantly higher in compared to 15% oak acorn and control treatments (p <0.05). At 21 days of age, expression of chymotrypsin gene in broiler pancreas was not significantly different between treatments containing oak acorn compared to control, while on day 42, expression of chymotrypsin gene was significantly higher in treatments containing 15% and 20% oak acorn in relation to the control group (P <0.05). In general, increasing the level of oak acorn in the broilers diet due to the increase of phenolic compounds (tannins) and their binding to dietary proteins and digestive enzymes can reduce the digestion and absorption of proteins and amino acids and increased expression of protein digestive enzymes in the gastrointestinal tract.

Tomato is the second most important vegetables, after potato, which has the highest area of cultivation worldwide. Acording to FAO statistics, Iran is the sixth producer of tomato cultivation in the world. However, more than 95 percent of vegetable seeds are imported into the country. The present study was conducted in order to evaluate commercial imported hybrids (8320, Eden, Matin and Xaman) and the F2 and F3 generations resulting from their self-breeding. In this regard, after the production of F2 and F3 generations, three generations (F1, F2 and F3) together with the control variety (Early Orbana y) were evaluated in the research farm of Seed and Plant Improvement Institute, Karaj, Iran, based on a randomized complete block design with four replications during 2019-2020. The analysis of variance showed that the difference among genotypes for single plant yield, days to flowering, average single fruit weight, number of fruits harvested and acidity (pH), was significant at the level of 1% probability and total soluble solids (TSS) was significant at the level of 5%. The results of the mean comparison showed that the highest mean of single plant yield belonged to 8320 F1 (10920/10g), the highest days to flowering was observed in Xaman F2 (47.01 days), the highest mean weight of single fruit was observed in Xaman F1 (115.50 g), the highest number of fruits harvested was in Xaman F1 (106.62), the highest amount of total soluble solids was in Matin F3 generation (4.96) and the lowest amount of acidity (pH) was in 8320 F1 (4.10). The results of estimating genetic parameters showed that most of the evaluated traits had high genetic and phenotypic variances, but a slight difference was observed between the coefficient of phototypic variation and the coefficient of genotypic variation, which indicates a small effect of environment on the control of these traits. Higher variance of dominance than additive variance in most traits caused the degree of dominance to be greater than one, Therefore, the possibility of control of traits by genes with dominance or over-dominance effects is high, and in order to improve these traits, the methods for hybrid development are suggested.

Rice is one of the important and staple food crops in Iran, and its grain yield improvement has always been the most important objective in rice breeding programs. One of the important breeding methods in rice is crossing between selected varieties to develop recombinant inbred lines (RILs), and then identifying promising lines. This experiment was carried out with the aim of identifying high-yielding superior lines. One hundred forty one recombinant inbrd lines together with their parental cultivars were evaluated using randomized complete block design with three replications in research field of faculty of agricultural sciences, University of Guilan, Rasht, Iran, in 2018. Important agronomic traits were measured and recorded for all RILs. Analysis of variance showed that there was significant differences among RILs for all studied traits, indicating significant genetic variation among them. Estimated coefficients of phenotypic and genetic variations as well as variance components also showed that there was considerable variation among RILs population, particularly for number of filled and unfilled grains panicle-1, number of panicles plant-1 and grain yield. The narrow-sense heritability varied from about 20% for panicle length to 43% for grain width, days to maturity, and 1000-grain weight. Factor analysis showed that three main and independent factors explained about 96% of the total observed variance among RILs, and were the main reasons for significant relationships between traits. These three factors were deignated as yield and its components, grain appearance quality and phenological factors. Cluster analysis by UPGMA method classified the 141 studied RILs into three clusters. Cv. Sepidrood and cv. Gharib (parental cultivars) were grouped in the first and second clusters, respectively. Evaluation of the cluster values for different traits showed that the first cluster had the highest values for grain yield and its components and the third cluster for grain dimensions and appearance quality. In conclusion, the results of this experiment showed that there was significant genetic variation among the studied RIls. Therefore, successful improvement of important agronomic traits, particularly grain yield and its components, is feasible. The superior high-yielding lines with desirable appearance quality were also identified.

One of the methods that has been used in recent years to deal with dehydration and drought stress in many plants is the use of root symbiotic fungi (mycorrhiza). Ecological and physiological studies have shown that mycorrhizal symbiosis often results in better absorption of water and nutrients from the soil. Due to the importance of oilseeds and especially sesame, the study of commercial cultivars in terms of genetic variation, phenotypic components and heritability of traits is important. Sesame due to its high oil content (52-42 Percentage) and its proper quality (low cholesterol and the presence of some antioxidants) play an important role in human health and on the other hand the plant tolerates dehydration and drought stress. Currently, water stress is the most important and common factor in reducing yield in arid and semi-arid regions. High heritability for a trait indicates that the major part of phenotypic variance is due to genetic variance, while in low heritability, genetic factors have a smaller share in phototypic diversity. The aim of this study was to estimate the variance components and heritability of grain yield and related traits in 8 commercial sesame cultivars under different irrigation conditions.

In order to investigate the genetic diversity and the heritability of grain yield and yield components in sesame, 8 commercial cultivars were studied in three separate experiments using factorial split plot based on randomized block complete design with three replications in research field of Agricultural Research Center, West-Azerbaijan in 2015-2016 and 2016-2017 cropping seasons. The main plots (factor A and B) consisted of three different levels of irrigations (normal irrigation: irrigation after 70 mm evapotraspiration of crop or ETc, moderate drought stress: irrigation after 90 mm ETc and severe drought stress: irrigation after 110 mm ETc) and factor B included three levels: two species of mycorrhiza fungi Glomus mosseae, Glomus intraradices and non-inoculated (control). Sub plots (factor C) consisted of eight commercial cultivars of sesame.

The results of analysis of variance showed that the effect of environment, genotype and the interaction of environment × genotype on most of the studied traits were significant. In optimal irrigation regimes, moderate and severe drought stress under inoculation and non-inoculation conditions with mycorrhiza, the highest genetic variance was observed in biological yield, number of seeds per square meter and seed yield, respectively. The highest heritability in optimum irrigation conditions without mycorrhiza inoculation of traits (seed yield and number of grains per capsule), in optimum irrigation conditions and inoculation with mycorrhiza (both two species) (seed yield and 1000 seed weight), in moderate drought stress conditions and no inoculation with mycorrhiza (seed yield, 1000 seed weight and number of seeds per capsule), under moderate drought stress and inoculation with mycorrhiza G. mosseae (1000 seed weight and number of grains per capsule), under moderate stress conditions and inoculation with mycorrhiza G. intradices (seed yield, 1000 seed weight and number of grains per capsule), under severe drought stress conditions and without inoculation with mycorrhiza (stem diameter and 1000 seed weight), under severe drought stress conditions and inoculation with mycorrhiza G. mosseae (stem diameter, number of seeds per capsule and number of seeds per square meter) and in conditions of severe drought stress and inoculation with mycorrhiza G. intraradices (stem diameter, number of seeds per square meter and 1000 seed weight) were observed. Seed yield, biological yield and seed yield components had high genetic gain and genetic advance in all three different irrigation conditions. Among the components of grain yield, considering that the heritability of number of seeds per capsule and 1000 seed weight in all three different irrigation conditions is higher compared to the number of capsules per plant, so selection through number of seeds per capsule and 1000 seed weight to increase seed yield will be more efficient.

Therefore, commercial sesame cultivars that have more seeds per capsule and a 1000 seed weight can be used in breeding programs to produce cultivars with high seed yield. According to the information of this study, only general heritability can be calculated, but since many studies on commercial sesame cultivars in interaction with different conditions of irrigation and inoculation and non-inoculation with mycorrhiza have not been done, so this study can useful for researchers.

 Applying the appropriate statistical method to genome wide association studies (GWAS (is one of the major factors influencing the identify chromosome regions effect of quantitative traits. The single-step genomic best linear unbiased prediction (ssGBLUP) approach, a quite common procedure in GWAS, has the advantage of simultaneously using the phenotypes of genotyped and non-genotyped animals, pedigrees, and genotypes; therefore, there is no need to calculate pseudo-phenotypes. It has been reported that the use of ssGBLUP procedure increased the accuracy of genetic evaluation in many contexts and species compared with pedigree-based BLUP. However, the ssGBLUP assumes that all SNPs explain the same amount of genetic variance, which is unlikely in the case of traits whose major genes or QTL are segregating. The weighted single-step genome wide association studies (WssGWAS) approach allows the use of different weights for each SNP according to their trait-relevant importance and improves the accuracy of genetic evaluation and the precision of estimates of SNP effects. Thus, The aim of the present study was to compare the explained genetic variance from multi-step Bayes B (MS-BayesB) method in the different values of π with weighted single-step genome wide association study (WssGWAS (method related to some economically important traits in 920 Japanese quails.

 For each bird, a total of three traits including body weight gain (BWG), feed intake (FI) and feed conversion ratio (FCR) were recorded and by using Illumnia iSelect 4K Japanese quail SNP Bead chip. For associations between traits and effective SNPs using the GenSel and BLUPF90 family software. The effects of markers and the genomic estimated breeding values of the traits were obtained by five iterations of WssGWAS. The proportion of additive genetic variance (agv) for each of 1.5-Mb genomic window (adjacent SNPs) was used to identify informative genomic regions and candidate genes, accounting for more than 1% of the agv. Also, to estimate SNP marker effects, the Bayes-B method was used (Meuwissen et al., 2009) with set π 0.90, 0.95, 0.99 The Bayes-B method assumes that some proportion (π) of SNP markers has zero effects. The posterior distributions of the parameters and effects were obtained using Gibbs sampling. We performed a Markov chain Monte Carlo (MCMC) simulation of 41,000 rounds with Gibbs sampling, of which the first 1000 iterations were discarded as burn-in. To estimate posterior means and variances of marker effects, Metropolis–Hastings samples were run for 10 iterations. The QTL windows were identified and located for candidate genes using the Coturnix_japonica_2.0 assembly. DAVID v6.8 Functional Annotation Tool (Huang et al. 2009) was used for gene ontology (GO) enrichment in order to detect biological terms associated with genomic regions and gene networks identified in the analysis. Enrichment analysis of gene function was performed using implementation of the Bonferroni test of overrepresentation.

These unknown genotype individuals can supply additional information to improve the statistical power of QTL detection. Sample size can influence the power of GWAS. In general, the results showed that the Bayes A method performed better in explained additive genetic variance compared to BayesB method with π=90. A total of 15 significant windows over 1% explained genetic variance on 10 chromosomes were found for the BWG and explained 23.1% of agv. For FI, we identified 14 informative windows across 9 chromosomes, and explained 28.3% of the agv. Also, for the FCR, 12 significant windows were identified on 9 chromosomes and explained 27.4% of agv. The detected candidate genes in genomic regions played an important role in muscle development, feed intake and residual feed intake. Results of this study showed that use single-step Bayesian methods of phenotype, genotype and pedigree information simultaneously, had outperform in comparison than other multi-step BayesB method. Moreover, considering the identification of new genome regions and the key role of the mentioned genes in development of body weight and feed efficiency, the WssGWAS method can be validated for GWAS for economic traits in Japanese quail.

 In the present study, we identified a wide range of genomic regions associated with body weight gain and feed efficiency traits. The findings of this study provide an important foundation for future fine-mapping studies to more precisely elucidate the mutations affecting production traits in Japanese quail. Future studies should establish causative links between candidate variants and economically important phenotypes using functional analyses.

In order to determine the genetic parameters and heritability of different traits of sugar beet and also the relationship between traits, full-sib and hybrid genotypes were evaluated in separate trials at Miandoab Agricultural Research Station under salinity and normal conditions in 2017. In full-sib trial performed under salinity condition, root yield, sugar yield, white sugar yield, leaf relative water content, root dry weight, and root/shoot ratio, and under normal condition, root yield, sugar yield, root/shoot ratio and specific leaf weight had higher genetic variance than environmental variance and consequently had higher broad-sense heritability. In hybrid trial performed under salinity condition, for white sugar yield, potassium content, potassium/sodium ratio, nitrogen content, and leaf area, and under normal condition, for root yield, sodium content, potassium/sodium ratio and nitrogen content, genetic variance was high and as a result, broad-sense heritability was above 0.5. Therefore, these traits can be considered in breeding and selection programs. Under salinity condition, the narrow-sense heritability ranged from 0.16 to 0.66. The highest narrow-sense heritability was related to molasses sugar with 0.66, nitrogen content with 0.43, sugar yield with 0.38 and leaf relative water content with 0.38, respectively. Therefore, it can be concluded that these traits are partially controlled by additive effects and can be used for selection of different degrees. Under normal condition, the narrow-sense heritability ranged from 0.01 to 0.29 and the relative water content with 0.29 showed the highest heritability. Under salinity stress, heritability of root yield and sugar yield was moderate; so yield could be improved by long-term selection and hybrid production. The results of regression and path analysis showed that under salinity and normal conditions, when the root yield was considered as dependent variable, specific leaf weight, leaf area, and relative water content explained the variation among which the leaf area had the highest positive direct effect on root yield.

Improving crop yield under drought stress conditions is one of the most important goals of plant breeding. Drought tolerance is usually evaluated by plant yield under low water stress, but due to the influence of other traits under stress conditions, this trait alone cannot indicate drought tolerance of genotypes. Therefore, it is better in breeding programs to identify drought tolerance traits of genotypes and guide programs based on yield and other important physiological and biochemical traits. Determining the values of genetic variance and the additive part and the dominance of genetic variance in controlling traits under both normal and stress conditions is the basis for deciding how to use germplasms in different conditions, which researchers use based on different methods to estimate them. The aim of this study was to estimate the genetic parameters of quantitatively yielding and qualitative traits of sugar beet under drought and normal stress conditions for use in breeding programs.

To determine the genetic parameters of different quantitative and qualitative traits of sugar beet, two series of genotypes full-sib and hybrid (resulting from the meeting of some of full-sibs as paternal lines and two lines SC C2 and SC 261 as maternal lines) were studied under both drought and normal conditions, in Motahari's Research, Karaj in 2017. After testing, different physiological and qualitative traits of genotypes were measured in two environments and finally genetic parameters were calculated.

In full-sib experiment under stress conditions, sodium content, potassium/sodium ratio, nitrogen content, alkalinity coefficient, syrup purity, molasses sugar, leaf area, shoot fresh weight, shoot dry weight, root dry weight, root mass ratio, and root/stem ratio had more genetic variance than environmental variance, so they also had higher broad sense heritability. Therefore, due to high genetic variance, these traits can be used in breeding and selection programs. Under normal conditions, the amount of genetic variance was low in all traits and consequently, the general heritability was low. In hybrid experiment under stress conditions for sugar yield traits, sodium content, sodium/potassium ratio, nitrogen content, and leaf area, and normal conditions for sugar yield and sodium/potassium ratio there was high genetic variance and broad-sense heritability was observed above 0.5. Therefore, these traits can be considered for breeding and selection programs. In drought conditions, the highest heritability was related to potassium content 0.77, molasses sugar 0.65, extractable sugar percentage 0.48, syrup purity 0.44, and sodium content and relative water content with 43, respectively. So, these traits were controlled to varying degrees by additive effects. Under normal conditions, pure sugar with 0.4 and sodium with 0.44 showed the highest heritability.

The results showed that the genetic parameters calculated in the stress environment cannot be generalized to the non-stress environment. As a result, studying the genetic characteristics of lines and hybrids under different environments is inevitable so that the estimation of gene function can be more accurate.  In both environments, the narrow-sense heritability of root yield was low but in sugar yield was moderate. So, in improving root yield, hybrid products can be used, and in sugar yield, selection can be used in long and term generations, as well as hybrid production.

The study of the genetic structure controlling agronomic traits is one of the preconditions for selecting the appropriate breeding method. In order to analyze genetic of some agronomic traits of bread wheat using generation mean analysis, parents and different generations resulting from the cross of Marvdasht × MV-17 wheat cultivars were assessed in a randomized complete block design with three replicates under normal and terminal drought stress conditions in Research Farm of Razi University (Iran) during 2015-2016 cropping season. Based on the results of weighted ANOVA, a significant difference was observed between different generations for most of the studied traits under both conditions. Generations mean analysis revealed that in addition to the additive and dominance gene effects, a variety of epistatic effects also played a role in the inheritance of most traits, and therefore cannot hope for the success of selection in first generations. The role of additive gene effect was greater than the dominance one for plant height, peduncle length and awn length, indicating usefulness of using recurrent selection to aggregate these genes followed by selecting lines with favorable agronomic characteristics. The model of genetic control for most of the traits was similar under both conditions in terms of the presence or absence of non-allelic interactions and it has not been widely affected by drought stress. The broad-sense heritability for plant height, peduncle length and awn length was estimated to be high under both conditions. The broad-sense heritability for kernel yield was moderate estimated under both conditions, but the narrow-sense heritability was very low. In general, considering the greater role of the non-additive gene effect for most of the traits, the selection is suggested in advanced generations and after access to a high level of gene fixation.

Drought stress is a limiting factor for sunflower. Various reports have mentioned the effect of water stress and limited irrigation on sunflower for many respects, including phonological traits, morphology, agronomic and physiological. Sunflower is a crop that can withstand a variety of environmental conditions, particularly drought and due to the developed root system. It has high efficiency in absorbing water from the soil. Sunflower is one of the most important oil crops and due to its high content of unsaturated fatty acids and a lack of cholesterol, the oil benefits from a desirable quality. The aim of this study is to investigate the genetic diversity and the heritability of agro-morphological traits in confectionary sunflower under different levels of drought stress. 56 local populations were studied in three separate experiments in rectangular lattice design (7×8) with two replications at Agricultural Research Center of West-Azerbaijan province, Urmia, Iran in 2012. Water treatments were well-watered, moderate and severe water stress conditions so that irrigation was applied with 50%, 70% and 90% depletion of available water, respectively. Various agronomic and morphological traits were calculated based on measuring traits in sunflower. Productivity effort as a physiological trait was measured by dividing the total dry weight of reproductive organs (head) to the total dry weight of plant. The results showed that in all three different water treatment conditions, heritability of head diameter, stem diameter, plant height, grain and biological yield was more than other traits. In well-watered conditions, moderate heritability varied between 0.52% for number of seeds per head to 80.61% for plant height. In moderate drought stress condition, the maximum and minimum heritability belonged to head diameter (76.21%) and chlorophyll index (26.45%), respectively. In severe drought stress condition, the most and the least heritability was observed for stem diameter (83.64%) and number of seeds per head (0 %), respectively. Among yield components, the heritability of 1000-grain weight at three water treatment conditions was higher compared to number of seeds per head, so for increasing grain yield, selection via 1000-grain will be more efficient. For the traits of grain yield, head diameter, stem diameter, biomass yield, chlorophyll index, dry weight of leaf, head and head with grain, the heritability in severe drought stress was higher than optimum conditions and this showed that the phenotypic variance is a large proportion of the genetic variance of more favorable traits. Due to the fixed component in the numerator and the denominator of genetic variance, environmental variance decreased in drought stress conditions in comparison with optimum irrigation conditions.

In order to evaluate the effects of genomic and traditional selection methods onlong term response to selection, genetic variance and inbreeding, a base population of 100 animals was randomly mated for 50 generations. The simulated genome size for each animal was 10 Morgan that was equally divided between 10 chromosomes. On each chromosome, 1000 SNP markers were evenly located. Two traits with the heritability of 0.5 and 0.1 were simulated for each animal and 200 QTL were randomly distributed over the genome for each trait. BLUP method was used for prediction of traditional breeding value as well as estimation of SNP effects. Genomic breeding values of the animals for each trait were sum of SNP effects for all loci. After generation 51, animals were selected based on traditional breeding values or genomic breeding values for 15 generations. The results of this study showed that for both traits the genomic selection method increased response to selection, butdecreased genetic variance relative to the traditional selection. Greater response to selection and reduction in genetic variance was for trait with higher heritability. A twofold increase in the inbreeding coefficient was observed for traditional selection relative to genomic selection after 15 generations of selection.

Breeding for drought stress is one the important purposes in wheat cultivars breeding programs. Grain yield under drought stress is depended on phonological, morphological and physiological features. In order to investigate the general and specific combining ability and genes function under drought stress in three and two bread wheat lines and cultivars respectively, diallel one way cross was performed in Agricultural and Natural Resource Research Station, Tehran. Parents and hybrids (F1) seeds in the fall 2013, were planted in a randomized completely block design with three replicates. Number of grain in spike, number of infertile florets in spike, days to flowering, kernel weight and grain yield traits were evaluated. Results from analysis of variance showed that there are significant differences between genotypes. Results from diallel analysis based on Griffing’s experimental Method II, Model B showed that general combining ability (GCA) effect in all traits and specific combining ability (SCA) effect in all traits except number of infertile florets in spike were significant (P≤0.01). In addition, the ratio of GCA to SCA mean of squares was significant in all traits except days to flowering. Higher portion of additive genetic variance in mentioned traits indicate the higher heritability of these traits and this prepares the selection possibility in early generation for these traits.

Wheat (Triticum aestivum L.) is a major staple food crop for more than one third of the world population and is the main staple food of Asia. Over 800 million hectares of land throughout the world are salt affected. Salinity is a major obstacle to food production because it substantially reduces the average yield of major crops. This study was conducted to evaluate the response of 24 cultivars and genotypes of wheat (Triticum aestivum L.) to NaCl salinity at early seedling growth and correlation between affected morphophysiological traits and molecular markers. Genotypes grew in hydroponic nutrient solution, under control (tap water) and salt stress (45 and 90 mM NaCl) conditions. Results of ANOVA analysis showed that there are significant difference (in one percent P-value) between genotypes and all of measured traits in different levels of salinity. A total of 20 RAPD and 34 ISSR primers were tested to investigate genetic diversity in 24 wheat genotypes. Of these, only 15 ISSR and 6 RAPD primers produced polymorphic bands and were further used for genetic diversity and regression analysis. Cluster analysis was performed based on jaccard coefficient and all genotypes were divided into 4 groups. Average genetic distance between genotypes was 0.486, showed that there is considerable variation among these genotypes. Regression analysis, also, revealed that there are significant relations between measured traits and using markers were investigated.

In order to study the genetic variation, identification and selection of superior rapeseed lines in a F4 generation, 20 advanced lines were examined using a randomized complete block design with three replications in the field of Seed and Plant Improvement Institute (SPII), Karaj in 2008-2009. Results of analysis of variance showed that there were significant differences between genotypes for the number of days to initiating and terminating of flowering, number of days to ripening, main stem length, height of first branch from ground surface, main pod length, 1000 seed weight, oil content, seed and oil yield, plant height, number of primary branches, number of pods per branch and per plant. Number of days to beginning of flowering and ripening, 1000 seed weight with 98.27, 92.52 and 91.73 grams had the highest values for broad sense heritability, respectively. The traits like number like of pods per branch and per plant with 23.13 and 16.72 had the highest values for genetic coefficient of variation (GCV). Comparison of mean seed yield showed that the genotypes L1, L9 and Zarfam
with the yield values of 3.49, 3.34 and 3.13 t/ha had the highest performance among the examined genotypes, respectively. Correlation among the measured traits showed that oil yield had a positive and significant correlation with seed yield at 1% of probability level and the traits of oil percent and the secondary pod length showed negative and significant correlation with seed yield at the %10 of probability level. Based on cluster analysis, genotypes were assigned into three distinct groups. One of the resulting clusters consisted of high yielding lines that would besuitable for selection of superior and high yielding rapeseed varieties.

This research was conducted to determine genetic variation and estimate heritability for one mountainous population of wild service tree (Sorbus torminalis (L.) Crantz), named Ashak (2100 to 2300 m.a.s.l) were specified on central Mazandaran forests (Farim). Seeds were collected from twenty healthy mother trees and planted in Orimalek nursery (1550 m.a.s.l). To perform the progeny test, thirty seedlings were used from each one of the mother trees and planted in a randomised complete block design with three replications at beside the Orimalek nursery of Farim Corporation Wood. Ten seedlings from each one of the mother trees were randomly allocated to each replication on a row. Establishment, vigour, collar diameter, height growth and number of branches were recorded on the progenies during the two years period of the experiment. The results indicated that different between genotypes was statically significant (p<0.01) both in first and second year in their progeny collar diameter and height growth. Genetic variance and heritability of height growth was higher than another traits. Heritability of height for the two years were nearly constant. Based on these results according to high heritability of progenies height growth, the genetic variation was high in Ashak population and height would be regarded as more suitable characteristic for increasing the genetic gain by selection in mother trees.

To determine the genetic structure, general and specific combining ability of some important agronomic characters, eight rice cultivars including 5 lines and 3 testers were crossed in Rice Research Institute of Iran (RRII), at Rasht, in 2000. Parental lines and F1 were planted in a Randomized Complete Block Design with three replications in the year 2001. Eleven important agronomic traits including yield and its components were recorded. Analysis of variances based on line×tester method showed that the mean squares for all traits were significant at 1% level. General combining ability (GCA) was positive and significant for grain yield in Khazar and Salary. Kanto and Salari have showed a negative and significant GCA for fertile tillers, as one of the most important yield components. Lines 213, 229 and Domsiah had negative and significant GCA for days to 50% of flowering. The lines with positive GCA can inherit those characters to progenies positively. While the lines with negative GCA can negatively transfer those characters to progenies. Estimation of components of genetic variance indicated that the number of fill grain per panicle and days to 50% of flowering were controlled by additive gene effects. It indicated that these traits can be transferred into progenies. For traits such as grain yield, fertile tillers and length of flag dominant gene effects was predominant.

The theory and analysis of diallel crosses have been defined and developed by many scientists. Griffing in 1965 described the diallel analysis in four methods with four models. In this study estimation of genetic parameters through different methods of Griffing approach was compared. Seven lines of Brassica napus L. were crossed in all possible combinations including reciprocal crosses. Forty two F1s together with seven parents were planted using randomized complete block design with 2 replications. Combining ability analysis was carried out for 12 agronomic characters on the basis of four methods of Griffing’s approach. Estimation of additive (σA2) and dominance (σD2) genetic variances and calculation of dominance ratio (σD2/σA2) was carried out for these methods. The estimation of additive and dominance genetic variances in the method 3 were negative for all characters and in method 2 and 4 they were negative only for some characters. However, in method 1 additive genetic variance was positive for all characters. Considering the estimation formula for additive and dominance genetic variances it was concluded that, when mean square specific combining ability (SCA) is greater than mean square of general combining ability (GCA), estimation of additive genetic variance is negative. This situation was observed in methods 2, 3,and 4 but not in method 1. It was indicated that components of genetic variances was better estimated in method 1 than the other methods in this study. Results indicated that the method 1 provided consistent estimation of additive and dominance genetic variance and was superior in comparison with the other Griffing methods.