فصلنامه تحقیقات غلات
سال چهارم شماره 2 (تابستان 1393)

In this study, the morphologic and genetic diversity of 32 rice varieties were studied using 15 microsatellite (SSR) markers linked to QTLs controlling drought tolerance characteristics. The total number of alleles generated by each marker ranged from 3 alleles at RM317 locus to 8 alleles at RM3, RM228 and RM231 loci. The RM317 had the highest values for effective number of alleles, Nei’s gene diversity, Shannon’s information index and polymorphic information content (PIC) among the all studied markers. The studied genotypes were classified into 3 groups based on morphological characteristics under non-stress and -4 bar stress conditions and based on molecular data. Totally, results of current research showed that there was a suitable genetic diversity between and within the different rice groups. Furthermore, reaction of the studied varieties to -4 bar stress indicated that the variety Shiroudi and the Lines 44 and 831 had the highest root length as well as the highest tolerance while the varieties Binam, Domzard and Sadri had the lowest root length and the highest sensitivity to drought stress. Among the used markers, the RM153, RM317 and RM325 markers with the most number of effective alleles as well as the highest diversity criteria were the best markers to separate the rice varieties. Therefore, these SSR markers can be utilized in marker-assisted selection programs under drought stress condition after confirmation of the obtained results in other complementary experiments.

To determine some of stability parameters related to grain yield in salinity condition, 41 bread wheat genotypes were evaluated under two non-stress and stress conditions in research field of the National Salinity Research Center (NSRC) in Yazd province. The salinity of irrigation water was 2 and 10 ds.m-1 for normal and salt conditions, respectively. Result of analysis of variance showed significant differences between genotypes for grain yield and yield components in both normal and salt stress conditions. Roshan and Yazd local varieties with the average grain yield of 3791.25 and 3764.47 kg.ha-1 respectively, had the highest grain yield in normal and salt stress conditions. Evaluating the correlation coefficients between indices and average grain yield in both experimental conditions showed that the three indices of mean productivity, geometric mean productivity and stress tolerance index were the best criteria for the selection of tolerant genotypes to salinity stress. Also, the three-dimensional diagrams derived from each index and grain yield in normal and salt stress conditions confirmed that the Roshan and Yazd local varieties had the highest grain yield in normal and salinity conditions and were the most tolerant genotypes to salinity stress.

To evaluate quality attributes of three durum wheat genotypes, Osta/Gata, Dipper-6 and PI40100, under five seed densities, 200, 275, 350, 425 and 500 seed.m-2, a spilt plots experiment in randomized complete block design with four replications was carried out in research farm of Isfahan University of Technology. Genotypes were considered in main-plots and seed densities in sub-plots. Results indicated that the genotypes had significant diffrences for grain yeild and quality attributes except for SDS sedimentation volume. Osta/Gata and PI40100 genotypes had the highest and lowest grain yeild, protein yeild and test weight, respectively, but the highest values of protein content and wet and dry gluten were observed in PI40100 and the lowest values in Osta/Gata and Dipper-6 genotypes. Results of correlation coefficients showed that there were the positive significant correlations among the grain yeild, protein yeild and test weight, while the negative significant correlations were observed between the grain yeild, protein yeild and test weight with grain protein contant and dry gluten weight. Results from this stuidy indicated that increasing plant desity increases the grain yeild, protein yeild and hectoliter weight and decreases grain protein contant and wet and dry gluten weight.

The effect of anti-transpiration substances on dry matter remobilization of maize cv. SC 500 under water stress, a split plot experiment in randomized complete block design with three replications was conducted in Hamedan during 2009 growing season. Three irrigation treatments including irrigation after 60, 90 and 120 mm evaporation and anti-transpiration substances including 0.5 mM salicylic acid (SA), 50 ppm paclobutrazol (PBZ) and control were considered as main- and sub-plots, respectively. The anti-transpiration substances were sprayed on plants at 6 and 8 leaf stages. Results showed that SA under irrigation after 90 mm evaporation increased 20.15% and 34.59% and under 120 mm evaporation increased 23.55% and 37.95% of the remobilization of dry matter from stem and leaf, respectively, compared with control treatment. PBZ treatment also increased 13.33% and 16.51% of the remobilization of dry matter from stem and 27.73% and 29.96% from leaf under 90 and 120 mm evaporation, respectively, compared with control. Furthermore, dry matter translocation efficiency and contribution significantly increased under both 90 and 120 mm evaporation than the control, but under 60 mm evaporation, SA treatment decreased and PBZ treatment increased the rate, efficiency and contribution of the remobilization of dry matter from stem, leaf and spathe. SA increased 15.84%, 20.82% and 29.74% of the grain yield under 60, 90 and 120 mm evaporation compared with control, respectively, but the highest grain yield (10267.36 kg.ha-1) was achieved by SA under the 60 mm evaporation. In contrast, PBZ under the 60 mm evaporation decreased and under the 90 and 120 mm evaporation increased grain yield (17.52% and 21.65%, respectively), compared to control. Therefore, the application of salicylic acid and paclobutrazol anti-transpiration substances are recommended for alleviating effects of water stress in maize plants.

Reduction in genetic diversity caused extreme vulnerability of crops to pests, diseases and environmental stresses will result in reduced yield. The genetic diversity of 77 barely genotypes were evaluated using seven AFLP combination primers. A total of 245 bands were generated which 227 were polymorph with average of 32.42 polymorphic band per marker. Average percentage of polymorphism and polymorphic information content were 92.37% and 0.43, respectively. General evaluation of the genetic diversity statistics including the number of effective alleles, Nei’s gene diversity and Shannon’s index showed that three primer combinations of E90-M160, E100 M160 and E100-M150 had higher values than the other combinations and had a more obvious role in distinguishing of the studied genotypes. Therefore, these primers are recommended to further studies on barely using AFLP makers. Cluster analysis using the neighbor joining method assigned genotypes to six groups. This type of grouping was nearly consistent with grouping of the genotypes in term of cold, warm or temperate climate, but not as comprehensive accordance. The analysis of population genetic structure using STRUCTURE software showed that population structure is separable into two main sub-populations with 21 and 35 genotypes, respectively, and 21 genotypes were identified as mixed genotypes. Genotypes of each sub-population had most similarity for allele frequencies and genetic structure and are different from the other groups. Results from this research can be used in future breeding programs such as association mapping.

To evaluate the genetic diversity and detecting the most effective traits on yield of barley promising lines, two separate experiments were conducted based on randomized completely block design with three replications under non- stress and terminal moisture stress conditions. The lines had significant differences for all studied traits in both stress and non-stress conditions. In moisture stress condition, the lines 4, 6 and 9 had the highest and the lines 13, 16 and 17 had the lowest grain yield. Kernel weight per spike and 1000- kernel weight had the most important role for increasing of yield in the six rowed line number 9, while spike number per m2 and 1000- kernel weight were the most effective traits in two rowed lines 4 and 6. Spike number per m2 under non-moisture stress condition and spike number per m2 and 1000- kernel weight under terminal moisture stress condition had significant positive correlations with grain yield. The lines 2, 4 and 10 had the lowest and the lines 1, 13 and 18 had the highest variation for grain yield. Number of spike per m2 was detected as the most effective trait on grain yield in both moisture conditions. Furthermore, kernel weight per spike and peduncle weight under non- stress condition and kernel weight per spike and 1000 kernel weight under moisture stress condition were the most important traits on grain yield. Also, number of spike per m2 and awn length under non-stress condition and number of spike per m2 and stem length under moisture stress condition had maximum and minimum genetic diversity, respectively. The maximum and minimum heritability was also calculated for the number of kernel per spike and awn length, respectively. Results of this research showed that number of spike per m2 with the highest genetic diversity was the most effective trait on grain yield under both non-stress and moisture stress conditions and can be recommended to improve grain yield of the studied barley promising lines.

Salinity is one of the most important abiotic stresses that decreases agricultural production in arid and semi-arid soils. To study the effect of salinity on root characteristics, Sahara3771 (salt tolerant) and Clipper (salt-sensitive) cultivars were evaluated in a factorial experiment based on randomized complete block design with three replications under 100 mM NaCl and normal conditions in hydroponic culture. Salinity treatment was applied at three leaves stages and continued for five weeks. To establish salinity stress, 500 mL of NaCl along with the half concentration of Hoagland solution was added at first day of stress treatment and after second day and onwards, 1000 mL NaCl and complete concentration of Hoagland was used. Root length, volume, fresh and dry weight, chlorophyll fluorescence and K+/Na+ ratio were measured at 24 hours, three weeks and five weeks after stress application. Analysis of variance and mean comparisons revealed that 100 mM NaCl compared with normal condition caused a significant reduction in root fresh weight and the K+/Na+ ratio. Significant differences were observed among growth stages for root fresh and dry weight and K+/Na+ ratio and with advanced of growth stages, the mean of studied traits was increased. Significant differences were found between cultivars for root volume and fresh weight at 1% probability level. Maximum root length and volume was observed in Sahara 3771 at shooting stage. Salinity stress caused more reduction in root weight and K +/Na+ in the susceptible cultivar (Clipper) compared with tolerant one (Sahara 3771).