فهرست مطالب mehdi zahravi

In order to differentiate among susceptible and tolerant chickpea genotypes, different biochemical traits were investigated. A factorial experiment based on a completely randomized design was performed in three replications. A combination of two factors i.e. genotype (cold tolerant and suseptible line) and temperature (4 and 20 ° C), were used in this experiment. Leaf samples were prepared 12 and 72 hours after stress. Based on the results obtained, H2O2 content was significantly higher in the susceptible genotype under both conditions. Sequencing results comparison showed that the proline dehydrogenase gene expression was increased in the susceptible line. In addition, expression of an isoform of proline 5 carboxylate synthetase reduced in this line. Cold stress caused a significant increase in catalase activitiy in the tolerant cultivar. Decreased expression of a homologue of ascorbate oxidase in susceptible line showed a positive role of this enzyme and regulation of ascorbate homeostasis in the tolerant cultivar. Decreased expression of ABA hydrolase in the tolerant cultivar, decreased expression of ABA receptor in the susceptible line, expression of different ABI5 isoforms in the tolerant cultivar under stress as compared to the susceptible line indicated differences in ABA transduction pathway in the susceptible and tolerant genotypes. The result of this study clearly explained the differences between the biochemical responses of tolerant and susceptible chickpea genotypes in response to the cold stress, which could be considered as an indirect screening method for identification of chickpea genotypes tolerant unde rcold stress conditions.

In the Mediterranean climates with mild winters like Khuzestan province, Iran, wheat is planted in autumn, and heat stress occurs only during the reproductive growth stage of wheat. In these regions, delayed planting causes the flowering and grain filling stages to be exposed to high temperatures, and the quantitative and qualitative performance of wheat decreases. Genetic improvement is one of the strategies to combat heat stress. Considering the importance of genetic resources for tolerance to environmental stresses tolerance, the present research was conducted to screen the wheat genetic collection of the National Plant Gene Bank of Iran for tolerance to terminal heat stress and to identify tolerant accessions.

In plant materials of this experiment were 236 bread wheat accessions along with three control varieties (Chamran, Chamran2 and Aflak), which were planted in an augmented design in the research field of Agricultural and Natural Resources Research Center of Khuzestan province, Ahvaz, Iran, in 2015-2016 crop year. The experiment was carried out in two planting dates, on-time planting date according to the region's custom at late November as normal conditions, and delayed planting at early January with the aim of heat stress during the reproductive growth stage of wheat. The measured traits included spike length, 100-grain weight, plant height, number of grains per spike, number of spikelets per spike, number of florets per spikelet, number of days to heading, number of days to maturity, grain filling duration, and five spikes grain weight. For data statistical analysis, descriptive statistics were firstly estimated under both normal and heat stress conditions, and then the relationships among traits were investigated using correlation coefficients. Principal component analysis was used to reduce the volume of data and cluster analysis was perfomed to group the studied genotypes.

The results of this experiment showed that terminal heat stress reduced the average of all studied traits, so that the highest decrease was observed in five spikes grain weight and the number of grains per spike. Based on the results of correlation coefficients under both normal and heat stress conditions, a positive and significant correlation was observed between five spikes grain weight and yield components traits, and a negative and significant correlation between five spikes grain weight and days to heading and days to maturity. Based on the results of principal component analysis, 72.54% and 80.53% of the total variance were explained by two and three main components under normal and heat stress conditions, respectively. The results of principal component analysis also indicated that the wheat accessions KC12977, KC12980, KC13013, KC13043, and KC13087, with the characteristics of early flowering and early maturity and higher values of five spikes grain weight, number of grains per spike, grain filling duration and number of florets per spike, were valuable accessions and have the sufficient potential to be used in breeding programs for heat stress tolerance. The results of cluster analysis separated the studied accessions into six group, and the fourth group including 62 accessions along with the control cultivars, had the highest average for number of florets per spike, number of grains per spike, and five spikes grain weight, as well as the lowest average for days to heading and days to maturity under both normal and heat stress conditions. and were recognized as the most tolerant group to heat stress. by three main components. In addition, the studied accessions were divided into six groups using cluster analysis.

The results of this study showed that there was a high genetic diversity among the studied bread wheat accessions in terms of terminal heat stress tolerance. Some genetic samples such as KC12977, KC12980, KC13013, KC13043 and KC13087, were valuable genotypes for the traits of early flowering and early maturity, as well as grain yield and yield components. The high diversity in these genetic resources, especially the tolerant accessions identified in this experiment as above mentioned, can be used to improve heat stress tolerance in future breeding programs.

Wheat ranks second among cereals in term of global production, but it has been affected by ongoing global climate changes. Drought stress is one of the important factors contributing to the reduction in wheat production. Developing drought-tolerant wheat varieties currently presents a major challenge for wheat breeders. Complex multigenic and multitrait genetic control, high genotype-environment interaction, low heritability, and challenges associated with high-throughput screening of plant traits and genes effective in drought tolerance due to the involvement of numerous traits and positive and negative correlations among them are some of the factors that have made wheat variety improvement for drought tolerance a challenging task. Selecting drought-tolerant genotypes as a cost-effective and biologically superior approach to increasing wheat production in low humidity areas has always been considered by breeders. Screening wheat genotypes to identify drought tolerance sources is essential and can be useful in selecting appropriate and desirable parents for implementing beneficial breeding programs. Local plant populations such as landraces are valuable resources for environmental stress tolerance, including drought stress. Local plant varieties are heterogeneous populations with local adaptation that provide genetic resources capable of meeting the needs imposed by new and emerging agricultural challenges under highly stressful conditions. The aim of this study was to identify wheat accessions tolerant to drought stress for use in future breeding programs.

A total of 512 wheat accessions from the National Plant Gene Bank of Iran, along with the varieties Kavir, Roshan and Mahouti as controls, were evaluated for drought stress tolerance in the research field of Agricultural and Natural Resources Research Center of Yazd, Iran. The experiment was conducted in two separate augmented designs, one of which was considered to drought stress and the other to normal irrigation conditions. Drought stress was induced by limiting the irrigation cycle. Considering that out of the total studied genetic materials, 141 accessions survived, the evaluation of traits was perfoemed on both those surviving accessions and their corresponding counterparts in the normal experiment. For data analysis, descriptive statistics including minimum, maximum, average, and coefficient of variation were calculated. Correlation coefficients were estimated and tested to study the relationship between traits. Stepwise regression analysis was used to determine the role of each trait and to identify the important and influencing traits on five-spike grain weight. K-means cluster analysis method was used to separate the accessions. All statistical analyzes were performed using R and SPSS softwares.

The results of descriptive statistics showed that the highest coefficient of variation under normal and drought stress conditions were attributed to five-spike grain weight (23.35%) and number of fertile tillers per plant (31.67%), respectively. Five-spike grain weight had the highest decrease in range (51.3%) under drought stress compared to normal conditions, and the highest decrease in mean was observed for number of fertile tillers per plant (59.3%) and five-spike grain weight (40.5%), respectively. A large number of accessions showed superiority over control varieties under both normal and drought stress conditions, so that 97 accessions had five-spike grain weight more than the control varieties. The accessions KC12856, KC12776, KC12783, KC12767, and KC12697 with values of 6.77, 6.75, 6.22, 5.94 and 5.86 g, respectively, had the highest five-spike grain weight under drought stress conditions. Number of spikelets per spike, number of florets per spikelet, 100-grain weight and number of grains per spike had significant and strong correlation coefficients at 1% probability level with five-spike grain weight under drought stress conditions. Based on the results of stepwise regression analysis under drought stress conditions, three traits including number of grains per spike, 100-grain weight and spike length were the most effective traits on five-spike grain weight and explained 90.6% of it’s variation. The studied genetic materials were grouped into five separated clusters using K-means cluster analysis.

The results of this experiment showed the valuable potential of the studied germplasm to drought stress tolerance. Evaluating the relationships among traits revealed the significance of number of grains per spikelet, number of spikelets per spike, number of florets per spikelet, and 100-grain weight under both normal and drought stress conditions. A considerable number of accessions were superior to the control varieties under both normal and drought stress conditions, indicating the richness and valuable potential of these genetic resources for drought tolerance related traits. Therefore, it is recommended to continue screening and evaluating the wheat collection of National Plant Gene Bank of Iran to identify drought stress-tolerant genetic resources. Based on the results of cluster analysis, the control cultivars with different characteristics were grouped in the separate clusters, and a distinguished cluster of the studied wheat accessions with superior traits was also formed. The diverse germplasm or superior accessions identified in this study can be used to develope the genetic base in crosses or as parents in breeding programs.

Soil salinity, as one of the most important environmental stresses, is a serious threat to agricultural production. Currently, more than 20% of the agricultural lands, which includes 954 million hectares of the world's lands, is affected by soil salinity. Salinity is expanding daily and it is predicted that by 2050, more than 50% of the world's arable lands will be saline. The decrease in yield due to salinity stress in wheat is considerable and worrying, so that a 50% decrease in yield of durum wheat due to salinity of rainfed lands, and an 88% decrease in yield of bread wheat under irrigation with high salinity and and a 70% decrease in yield of bread wheat in sodic soils has been reported. The high levels of salt in soils and irrigation waters are worrying factors for agriculture, therefore it is necessary to develop the effective strategies to improve yield through salinity stress tolerance. The present study was carried out due to the importance of genetic accessions as sources of tolerance to biotic and abiotic stresses including salinity, and the existence of considerable genetic diversity in wheat germplasm to salinity stress tolerance. The objective of this experiment is to investigate the diversity of genetic accessions of bread wheat collection of Iran's National Plant Gene Bank, to compare the accessions with the tolerant control varieties, and to identify the new genetic resources for salinity tolerance.

To identify the genetic resources of salinity tolerance in wheat germplasm, 512 accessions from the bread wheat collection of the National Plant Gene Bank of Iran along with salinity tolerant varieties, Kavir, Roshan and Mahoti as controls, were investigated in two different augmented designs under normal and salinity stress conditions. The normal experiment was carried out at the research field of Yazd Research Center and the salt experiment was done at saline lands of Ardekan Research Station. The studied traits included spike length, spike density, 100-grain weight, number of tillers, plant height, number of spikelets per spike, number of florets per spikelet, number of grains per spike, days to heading, days to maturity, grain filling period and grain weight of five spikes,  which were recorded according to the international description. To perform data statistical analyses, descriptive statistical indices were first calculated and then the studied accessions were grouped using K-means cluster analysis. Discriminant function analysis based on principal components was used to investigate the differentiation between the groups resulting from cluster analysis. Statistical analyzes were performed by SPSS and R softwares.
 
 
Research

The results showed that grain weight of five spikes (with a minimum of 4.15 and a maximum of 12.26 g in normal conditions and a minimum of 2.19 and a maximum of 9.78 g in stress conditions) and the number of spikes (with a minimum of 3 and a maximum of 8 in normal conditions and a minimum of 3 and a maximum of 7 in stress conditions) had the highest coefficients of variation, while days to heading (with a minimum-maximum of 130-163 days and 126-168 days in normal and salinity stress conditions, respectively) and days to maturity (with a minimum-maximum of 173-189 days and 168-196 days in normal and salinity stress conditions, respectively) had the lowest coefficient of variation under both normal and salinity stress conditions. A large number of superior accessions were identified for various traits compared to the control cultivars under both normal and salinity stress conditions. The results of stepwise regression indicated the importance of three characteristics, 100-grain weight, number of grains per spike and number of florets per spikelet, in describing the variation of grain weight of five spikes. The investigated accessions were divided into five groups using K-means cluster analysis and the control cultivars were separated into different groups so that Roshan and Mahooti along with 70 accessions were grouped in the first cluster and Kavir along with 53 accessions in the fifth cluster.

The results of this experiment showed the presence of significant and valuable genetic diversity in traits related to salt stress tolerance in the studied bread wheat germplasm. The effect of salinity stress on different traits of the studied accessions was different. Among the studied traits, 100-grain weight, number of grains per spike and number of florets per spike were more important, so they can be used in breeding programs. A large number of accessions were also superior to control cultivars for various traits. Cluster analysis grouped the control cultivars into distinct clusters, which indicates different aspects of salt stress tolerance in these cultivars. The superior accessions identified in this research can be used to improve salt stress tolerance in bread wheat breeding programs.

Wheat powdery mildew caused by the biotrophic fungus Blumeria graminis f. sp. tritici, is a serious threat to wheat production in many regions of the world. This disease can reduce the yield up to 45% and reduce the quality of the grains by affecting the flour protein. Due to the adoption of high-yield crop systems that require high use of nitrogen fertilizers and high irrigation, as well as due to climate changes towards milder winters and increased rainfall in wheat production areas, the importance of powdery mildew disease is also increasing. One of the most useful strategies to control powdery mildew disease is to identify the sources of resistance among germplasm, which is also known as the most economical method among farmers. This research was conducted to identify resistant genetic samples to powdery mildew in the bread wheat collection of the National Plant Gene Bank of Iran.

The plant materials of this research were 173 accessions of bread wheat from the collection of the National Plant Gene Bank of Iran received from different countries, which were investigated to identify the sources of resistance to powdery mildew under natural incidence conditions at the research stations of Gorgan and Sari as the disease hotspots during three crop years (2018-2021). A two-digit scoring system was used to evaluate the response of the genotypes to the disease, in which the first digit is measured based on the infection development in plant height and the second is measured based on the disease severity in terms of the infection percentage on flag leaf surface. Then, by combining these two criteria, disease development and disease severity, the infection coefficient was calculated and used for the statistical analysis. K-means cluster analysis was used to group the germplasm and determination function analysis based on principal components was used to confirm the cluster analysis results. The relationship between the reaction of accessions in different years and locations was also investigated using multidimensional scaling analysis, and then the stability of the studied accessions over the experimental years and locations was investigated using the Wricke’s equivalence stability criterion based on the infection coefficient.

The results of this experiment showed that the average coefficient of infection during the studied three crop years varied from 0.05 to 0.29 percentage in Sari station and from 0.25 to 0.29 percentage in Gorgan station. The studied genetic materials were separated into five groups using K-means cluster analysis, and the fourth group consisting of 68 accessions was identified as the most resistant group. Based on the results of this experiment, the accessions KC 5292 (Turkey) and KC 5824 (Austria) were identified as the resistant genotype, and the accessions KC 5389, KC 5579 and KC 5476 (Iran), KC 5772, KC 5773 and KC 5384 (Afghanistan), KC 5133 and KC 5147 (Portugal), KC 5715 (Japan) and KC 5801 (unknown origin) as the resistant to semi-resistant genotype, and had the most stable response to the disease in various environments.

The results of the current research showed that there is a suitable genetic capacity to identify sources of powdery mildew resistance in wheat genetic stocks. The superior and resistant genetic materials identified in this research can be used to improve resistance to powdery mildew in wheat in the future breeding programs.

Leaf rust is one of the most important wheat diseases in the world and Iran and the use of resistant cultivars is the most effective tool against this disease, however, the resistance of the cultivars becomes ineffective following a selective pressure on the pathogen, which makes the search for new resistance genetic resources unavoidable. The present study was performed to identify these sources of resistance in wheat germplasm. Therefore, 97 accessions from the bread wheat collection of National Plant Gene Bank of Iran were investigated under natural infection condition at Eraghi-Mahale Research Station, Gorgan, Iran, in 2017-2018. The results showed that 46.4% of the studied accessions had a zero infection coefficient that were selected for evaluation at the seedling stage. Seedling evaluation was performed in greenhouse using four pathotypes with determined virulence-avirulence factors. The results of qualitative and quantitative analyzes grouped the studied accessions into different groups with specific resistance to one or more pathotypes. Comparison of resistance response of the accessions with avirulence/virulence formula in the pathotypes indicated the possibility of presence of Lr14a in the accession 5127. Furthermore, these comparisons revealed the possibility of presence of unknown resistance genes in many of the accessions under study. The results of this study showed the valuable capacity of the bread wheat germplasm to possibly identify new genes and sources of resistance to leaf rust. Therefore, it is suggested that additional research be done to evaluate and screen the bread wheat germplasm.

Terminal heat stress has been recognized as the most widespread and detrimental type of heat stress in the world. In southern regions of Iran like Khuzestan, delay in planting date causes pollination and grain filling stages to be exposed to high temperatures, resulting in yield reduction. Developing heat tolerant cultivars is one of the ways to deal with heat stress. In this study, to identify resources of heat tolerance in wheat germplasm, a total of 203 bread wheat accessions with three control cultivars were planted in normal and delayed planting dates as an augmented experimental design in Ahwaz and the agronomic traits were evaluated. The results showed that almost all the evaluated traits were reduced in heat stress conditions compared to normal conditions. In both normal and heat stress conditions, some superior accessions were identified in terms of the studied traits compared to the control cultivars. In the biplot based on the principal components under heat stress conditions, 64 accessions along with control cultivars were located in the area of superior characteristics in terms of grain weight of five spikes, number of florets per spike, number of grains per spike, number of spikelets per spike, spike length and plant height. The studied accessions were divided into five groups by cluster analysis. The results showed a high diversity in the studied genetic material and the accessions superior to the control cultivars in terms of the studied traits were identified which can be used in future breeding programs.

Barley yellow rust is one of the important barley diseases in the world. However, the importance of this disease has recently increased in Iran. The main aim of the present study was to identify the sources of resistance to this disease in a collection of Iranian barley genotypes provided from the National Plant Gene Bank of Iran (NPGBI). For this purpose, a set of 128 accessions of the north and northwest regions of Iran were assessed in terms of resistance components such as disease severity, infection type and coefficient of infection under natural incidence of the disease in the field of Ardebil Research Station as a hotspot region for barley yellow rust during 2019-2022 cropping seasons. The results indicated a considerable genetic diversity among the tested genetic materials in response to this disease. A moderate correlation was observed between the evaluations of different years. The accessions were separated into five groups using cluster analysis, and the second group with 41 members with the lowest infection coefficient average was identified as the most resistant group. The results of this research showed the high capacity of the collection to identify sources of resistance to barley yellow rust disease. The identified resistant germplasm can be used in breeding programs for resistance to this disease.

Salinity is one of the most important environmental stress which limits growth and yield of crops. Breeding and development of tolerant varieties is the most effective approach to confront salinity. Improvement of tolerance to salinity in crops necessitates existence of diverse genetic resources. Genetic variability for salinity tolerance has been reported. Wheat germplasm is a valuable genetic resource for tolerance to abiotic stresses including salinity. This research was performed with the objective of screening and selecting salinity tolerant genotypes in wheat germplasm.

A total of 97 bread wheat genotypes selected from previous studies along with three tolerant check cultivars of Kavir, Roshan and Mahooti were planted in research filed of Karaj (normal condition) and Meybod (saline soil and irrigation water, EC=6.55 ds/m and 5.61 ds/m, respectively) in lattice statistical design with three replications. Agronomical traits were evaluated according to international descriptor. Stress tolerances indices were calculated and the superior genotypes were distinguished by analyses of cluster and principal components. Stepwise regression was used in order to identify effective trits in tolerance to stress.

Grain yield of the check cultivar Kavir was higher than Roshan and Mahooti in stress condition. A total of nine genotypes had higher grain yield in stress condition than Kavir. Genotype KC.4419 had the highest amount of grain yield in normal condition (966.67 g/plot) and the highest values for the indices STI, GMP, HM and HM. The indices STI, GMP and MP had high correlations with grain yield in both normal and stress conditions. The studied genotypes were separated in the biplot of grain yield in normal and salinity stress conditions. A total of 38 genotypes along with all three check cultivars having higher grain yield in normal and salinity stress conditions were located in Region A of biplot. The results of principal component analysis based on the evaluated traits along with STI indicated that three PCs comprised 74.79% of the total variation. While the first PC emphasized on obtaining higher grain yield in stress condition through increasing grain filling period and producing larger seeds, the second PC highlighted the accumulation of dry matter in vegetative tissues. The results of stepwise regression for STI showed that harvest index entered in both models of normal and salinity stress conditions. The trait appeared specifically in regression model of stress condition.

The genotypes KC.1514, KC.4382, KC.4419 and KC.4407 (from Esfahan), KC.142 (from Khoy), KC.3100 (from Mashhad), KC.1143 and KC.388 (from Iran with unknown province) and KC.106 (from USA) with higher grain yield in stress condition than check cultivars were selected as tolerant genotypes. STI, GMP and MP were suggested as the most suitable criteria for selecting superior genotypes in salinity stress condition due to their high correlations with grain yield in both normal and stress conditions.

This research was performed with the purpose of screening of wheat genotypes and identification of resistance sources to yellow (stripe) rust disease. A total of 284 accessions from bread wheat collection of National Plant Gene Bank of Iran, which were previously received from 19 countries, were evaluated at adult plat stage under natural incidence of the disease in field condition of Sari, Iran. Based on components of resistance, 116 genotypes were selected for study in the second year at the same condition, among them 52 accessions were then chosen for evaluation at seedling stage in greenhouse. This evaluation was performed by four races 38E158A+, Yr27, 174E10A+, Yr27, 6E2A+, Yr27 and 238E190A+, Yr27. The results showed that 9 genotypes including 8252 and 8320 (Iran), 8395 and 8396 (Korea), 8103 (Afghanistan), 8150 (Portugal), 8348 (Algeria), 8426 (India) and 8472 (Turkey) were resistant to all the studied pathotypes. The presence of Yr1, Yr4, Yr10, and YrSP genes were postulated for these genotypes. One genotype from each country of Portugal, Iran, Japan, Korea, Italy and five genotype with unknown origin were resistant only against pathotype 6E2A+, Yr27, which are likely to carry YrSD or YrND. The comparison of resistance reactions in genotypes 8257, 8237, 8259 and 8332 (Iran), 8105 and 8108 (Afghanistan), 8169 (Portugal), 8458 (India), 8152 (Portugal) and 8362 (Australia) and virulence factors in the studied pathotypes suggested the presence of some unknown resistance genes in regarding genotypes. In the present study some genotypes with adult plant resistance were also identified. The total results of this research indicated the potential of bread wheat collection of National Plant Gene Bank of Iran to identify new sources and genes for resistance to yellow rust.

Wheat powdery mildew caused by fungal pathogen Blumeria graminis f.sp. tritici is a destructive wheat disease, occurring in regions with cool and humid climates. In order to investigate the changes in pathogenicity of the disease and to identify the effective genetic source of resistance, a total of 29 wheat genotypes with different resistance major genes (Pm) were studied in two hotspots of Gorgan and Sari under natural incidence of the disease over 2015-2018. Resistance reaction of the genotypes was evaluated by disease development, disease severity and coefficient of infection. The results indicated that mean of coefficient of infection for Gorgan was larger than that for Sari in all three years of the study. The reaction of some genotypes showed apparent differences between the two regions during the years of study. The highest genetic distance was observed between Ralle (Pm3d) and Holger (Pm6). NK-747 (Pm6) and Maris Huntsman (Pm2+Pm6) as well as Amigo (Pm17) and Maris Huntsman (Pm2+Pm6) showed the highest genetic similarities to each other. A total of 65.78% of the data variation was justified by principal component analysis on the basis of the coefficient of infection. The genotypes Maris Dove (Mld+Pm2), Shamrock (with unknown Pm), Broom (Pm3d) and Axona (Pm2+Pm3d+Mld) expressed effective resistance over the years and locations. The total results of this research indicated variations in the virulence of wheat powdery mildew population during the years of the experiment. This finding emphasizes on the necessity of constant monitoring of the disease in the infected areas. The genes with effective resistance identified in this study could be used in resistance breeding to powdery mildew especially for Gorgan and Sari.

The barley leaf rust has been important in recent years in Iran. In order to identify the genetic resources of resistance to this disease, 207 Iranian barley landraces were studied. The germplasms were investigated at the field of Iraqi-Mahalleh research station in Gorgan as the disease hotspot under natural incidence over three years. The results showed that four genotypes including KC18638 and KC18643 from Golestan and KC19087 and KC 19093 from Gilan expressed immunity response in all three years of the experiment and 31 accessions were immune in two years. The results of principal component analysis in three years showed that 90.69% of the variations in the data were justified by the first three principal components. The results of this study indicated the possibility of racial variation in the studied disease hotspot. These findings show the importance of tracing the changes in the disease hotspot which is necessary for planning, breeding and cultivation of cultivars with effective resistance. Also, the resistant genotypes identified in this research can be used as genetic resources of leaf rust resistance in breeding programs.

Food legumes are a central part of the diet for many communities around the world and lentil could be an excellent choice to provide more nutritious foods. Lentil breeding program aims to develop adapted, high yielding, biotic and abiotic tolerant varieties. The success of any breeding program is dependent on the availability of genetic materials with sufficient diversity. In order to investigate the genetic diversity in elite germplasm of lentil, a total of 138 genotypes received from ICARDA were evaluated in research field of Seed and Plant Improvement Institute during 2015-2016 cropping season. These materials were studied in an observatory design by evaluating 28 quantitative and qualitative traits according to the Bioversity international descriptor. Results indicated that the highest Shannon index belonged to ground color of testa (1.33), testa pattern (0.85) and color of testa pattern (0.8). The traits seed weight per plant (CV=111.23%), grain yield (CV=81.58%) and pod weight per plant (CV=72.55%) had the highest coefficient of variation. The highest 100-seed weight and grain yield were recorded for genotypes 118 and 69, respectively. Genetic relatedness of genotypes was investigated by their pedigrees and values of genetic distance. Analysis of proximity values based on quantitative traits showed that genotypes 6 and 114 had the highest similarity and genotypes 42 and 130, had the highest genetic distance. The results of discriminant analysis of principal components indicated a successful classification based on quantitative traits in differentiating groups of genotypes. Totally, results indicate the presence of a valuable genetic diversity which could be used in advanced breeding programs.

A total of 17 wheat landraces were evaluated for resistance to powdery mildew in filed and greenhouse environments. The field experiment was performed at three disease hotspots in Sari, Gorgan and Moghan under natural disease incidence and the reaction of the genotypes was evaluated at adult plant stage. In order to evaluate the resistance of the genotypes at seedling stage, the isolates of the disease were collected from different regions and the pathotypes were identified by inoculation on the differential varieties. The results of field evaluation indicated that average reaction level of genotypes to the disease in Sari and Gorgan was similar and both lower than that of Moghan. A total of ten pathotypes were distinguished, all of which had virulence factors for Pm3a, Pm3c, Pm3g, Pm4a, Pm5, Pm6, Pm8 and Pm2. The varieties Shamrock (with unknown R gene), Normandie (Pm1+ Pm2+ Pm9), Axona (Pm2+Pm3d+Mld), Maris Dove (Mld+Pm2) and Wembley (Pm12) were resistant to all the pathotypes. The presence of Pm7 was postulated in genotype 7 as the resistance spectrum of this genotype was similar to that of Transfed. Genotypes 4 and 11 appeared resistant and moderately resistant at adult plant stage while they were susceptible to all pathotypes at seedling stage and therefore they were identified as genotypes with adult plant resistance. The total results of this research led to identification of seedling and adult plant resistance sources with different resistance gene combinations which could be exploited in breeding programs.

A total of 117 pomegranate genotypes collected from different areas of Yazd province of Iran were studied for genetic variation by evaluating 23 morphological traits according to the international descriptor. Similar diversity pattern of the measured characteristics was observed in three types of sweet, sweet-sour and sour varieties. The traits shape of fruit base, suckering tendency, vigor of tree, fruit shape and aril color had the highest power of discrimination. The results of evaluation of genetic distances revealed discrepancies in the pairs of genotypes with similar denominations. The sites of Taft and Yazd were located in the same group in the dendrogram of origins of the germplasm, while Bafq and Ardakan together were placed in another group separated from group of Ashkezar and Mehriz. Abarhuk and Khatam regions also made single-membered groups. The results of discriminant analysis revealed that a large number of genotypes were assigned to their original collecting locations with low probabilities indicating a high degree of genetic exchanges. The genotypes were separated in 11 different groups by K means clustering method with defined characteristics. The supplement of characterization of the germplasm was suggested through evaluating commercial traits and by molecular markers.

In order to evaluate the traits related to nitrogen utilization and to identify the superior genotypes, 33 bread wheat landraces along three check cultivars of Chamran and Koohdasht (from Iran) and Gobustan (from the Republic of Azerbaijan) were studied in simple lattice statistical design with two replications under two treatments of non-usage and application of 200 kg/ha ammonium nitrate fertilizer in research field of Seed and Plant Improvement Institute located in Karaj, Iran. The results indicated that the diversity of nitrogen uptake was higher than that of nitrogen use efficiency based on coefficient of variation. Genotype 4 (from Iran) and Chamran showed the highest value of nitrogen uptake efficiency. The highest amount of nitrogen use efficiency belonged to the genotypes 4 and 7 (from Iran). In the biplot of nitrogen uptake and use efficiency, check cultivar Chamran along with genotypes 4, 19, 21 and 23 (from Iran) and 2, 3 and 9 (from the Republic of Azerbaijan), which were superior for both traits were located in region A of Fernandez grouping. Generally, based on the results , a high varation in nitrogen components was revealed in the studied germplasem, particullary in Iranian landraces which could be used as gene pool for breeding programs.

Biodiversity ensures the existence of every ecosystem. Among the levels of biodiversity, genetic diversity, as raw material for breeding, has gained more attention in agricultural societies, scope of which is considered as a durability index of productivity. Genetic resources constitute the foundation of modern agriculture and are necessary for attaining food security. The hazard of loss of genetic resources first came into the attention of scientists in middle of twentieth century, followed by universal implements to protect these valuable reservoirs. However, breeding methods per se restrict genetic base and cause genetic vulnerability against unfavorable environmental conditions and biotic stresses. On the other hand, high potential existing in genetic resources, as repository of precious characteristics, has remained unutilized. The advent of genetic engineering modified many concepts in various domains including genetic resources. Having the capacity to pass the limiting borders, this technology is promising to make concealed potential of genetic resources free and enhance germplasm. Genetic engineering targets and harnesses harmful pests, conserving the useful organisms. This technology has prevented the soil erosion through encouraging the farmers to adopt conservation agriculture methods in different countries leading to biodiversity conservation of the soil. Having in mind the valuable attainments of genetic engineering in food production and security and great revolution expected by this technology in future, it may be stated that human being has entered a new era of supplying his basic necessities.

Drought is one of the most significant a biotic stresses that affecting plant’s growth and development wild barley, H.spontaneum, the progenitor of cultivated barley has a high potential in terms of tolerance to environmental stresses. This research was performed on nine genotypes of Hordeum spontaneum, to study drought tolerance in a split plot experiment based on Randomized Complete Block Design with three replications under field shelter in 2011-2012. The main plot included three levels of water stress as normal irrigation, water withholding at flowering stage and no irrigation and sub-plots comprised the studied genotypes. The results indicated that the effect of drought stress on plant height, grain yield, biomass, relative water content, osmotic adjustment, stomatal conductivity, chlorophyll content, catalase, ascorbate peroxidase and peroxidase, protein, malondialdehyde, and proline was significant (P

In order to identify drought tolerant germplasm, 97 bread wheat landraces, mostly Iranian genotypes, were evaluated in two separate experiments of normal and drought stress conditions in the field of Agriculture and Natural Resources Research Center of Varamin. The experiments were performed in lattice statistical design with three replications. Drought conditions in the stress experiment was exerted by irrigation stoppage at the spike emerging stage. Agronomic traits were measured and drought tolerance indices were calculated. The results of combined ANOVA indicated significant differences among genotypes and between conditions as well as genotype × conditions interaction for all the evaluated traits. STI, GMP, HM and MP were known as the best indices for the selection of drought tolerant genotypes. Thirty genotypes, located in A region of Fernandez grouping method, had a higher grain yield in both stress and normal conditions. Four principal components explained 71.44% of the total variation. The first component differentiated drought tolerant genotypes with early spike emerging and the second one emphasized on later spike emergence, larger harvest index and shorter plant height. The results of this research identified a large number of superior drought tolerant genotypes which could be exploited in wheat drought breeding programs.

To evaluate the effects of water deficit stress in barley germplasm collection of National Gene Bank of Iran، 25 genotypes collected from arid and semi arid provinces of Iran and 3 sample cultivars were studied in two environments including: non-stressed and water deficit stress. Agronomical، phenological and morphological traits were measured. Stress indices were calculated to determine tolerant genotypes. Based on correlation coeficiences، STI were better indicator of drought stress tolerance than the other indices. Based on STI، morphotypes number 16، 24، 25 and 26 shown better stress tolerance potential than the other morphotypes. Stepwise regression between stress tolerance index (STI) and quantitave traits indicates the important role of leaf area and specific leaf area of flag leaf under drought stress condition، in acclimation to drought conditions. It is also concluded that the 100 grain weight is the only trait under normal condition witch shows a close relation with stress tolerance index.

Genotypic variation is useful to breeders when selecting genotypes to improve particular traits. Inorder to study of genetic diversity 20 genotypes of Hordeum murynum studied in the form of randomized complete block design the experimental field of islamic azad university shahre rey branch with 3 replication in the year 2012. Notes traits was conducted including days to heading, days to maturity, plant height, straw weight, harvest index, grain number per panicle, 10- panicle weight, 100- grain weight, biomass and grain yield. The results of analysis of variance showed that the significant differences were observed among genotypes for all morphological traits, except days to maturity and harvest index. Mean of traits classified using Duncan's multiple range test (p = 0.05). Line of 12-1092 produced the highest Plant height, days to heading, 10- panicle weight straw weight, biomass and grain yield. Correlation coefficients showed the grain yield has a positive at p= 0.05 and significant with biomass (r=0.97), number of nodes on the stem) r=0.72), 10- panicle weight (gr) and plant height. Stepwise regression analysis, grain yield as the dependent variable (Y) and other traits evaluated was considered as an independent variable (X). Results showed that the biomass and grain yield (with biomass) with 93.7% and 98.8% explained the maximum grain yield variation, respectively.

In order to study genetic variation and relationship between traits، 615 accessions of local bread wheat from wheat collection of National Plant Gene Bank of Iran were evaluated. Seeds of the accessions were planted in 2. 5 meter long rows in an observatory design and 17 agro-morphological traits were measured. Grain yield of 5 spikes، number of tillers and number of seeds per spike were of highest diversity among quantitative traits based on coefficient of variation. Among qualitative traits، glume color had the highest Shannon index. Two independent variables of number of seeds per spike and 100-seed weight were entered the model of stepwise regression determining 98% of grain yield of 5 spikes as dependent variable. The results of PCA indicated that the first five components comprised 63. 28% of the total variation in data. Based on coefficient of variables the components were designated as large seed size and high yield، yield components، biomass production، qualitative characteristics of spike and lodging resistance indices، respectively. The results of principlal component analysis distinguished accessions 200 (West Azarbayjan)، 763 (Gilan)، 835 (Lorestan) and 845، 846 (Isfahan، Both) as superior ones. The cluster analysis distinguished origins of the accessions in four groups. The result of this investigation showed a valuable variation in local wheat germplasm which could be exploited in breeding programs.

Four advanced breeding lines of wheat which had appeared to be resistant to stripe rust in the past years along with a susceptible variety, Bolani, were intercrossed in all combinations of a half-diallel design. Seedlings were grown in greenhouse until the first leaves fully expanded and then inoculated with two pathotypes (races) 6E134A+ and 134E148A+, separately. Days to the first pustule eruption was recorded as latent period. Diallel analysis was performed by two methods of Griffing, and Jinks and Hayman. M-78-1 and M-78-10 were known as the best general combiners for longer latent period. Results of the analysis of variance of Wr+Vr and Wr-Vr, Wr/Vr regression analysis and estimates of genetic parameters indicated the importance of both additive and non-additive gene effects. Broad-sense heritability was 98% for both pathotypes. Narrow-sense heritability was 65% and 80% for 6E134A+ and 134E148A+ pathotypes, respectively.

Wheat landraces are considered as valuable sources of tolerance specially for severe environmental stresses. Exploiting local genetic resources has become doubly important regarding narrow genetic base due to plant breeding. Twenty seven local and foreign genotypes selected from 4096 populations of wheat collection of National Plant Gene-Bank of Iran along with three control varieties، Mahooti، Kavir and Roshan، were evaluated in three separate experiments، one normal and two saline (Ardekan and Meybod) conditions. STI and GMP were identified as the most favorable indices to select salt tolerant cultivars based on correlations with grain yield in stress and non-stress conditions. Two genotypes of 4383، from Isfehan، and 7122، from Argentina، were superior based on stress tolerance indices، and yield in both stress environments. Despite the lowest amount of yield of the genotype 4419 in non-stress condition، it possessed the lowest amount of yield loss due to salt stress، and the lowest amount of TOL and SSI which could be an indication for a specialized mechanism for salt tolerance. Based on Frenandez classification، genotypes of 3888، 4383، 7097، 7122، 7258 and Mahooti were placed in group A، genotypes of 142 and 4407 were placed in group B، Kavir was placed in group C and genotypes of 1143، 3700 and 4355 were placed in group D commonly in both Ardekan and Meibod experiments. Cluster analysis based on stress tolerance indices could discriminate the genotypes consistent with Fernandez classification.