Determination of the most effective traits on grain yield of some barley genotypes under normal irrigation and drought stress conditions

Introduction Drought, environmental stress is the most common, that about 25 percent of the acreage limit, the occurrence of stress significantly reduced biological yield, grain yield, harvest index and water use efficiency is sometimes. Although the Barley is more tolerant to drought than other cereals, but this plant during its growth and development, in both stem elongation and grain filling sensitive to water deficit, and drought in the steps leading to the reduction of its performance. Flowering stage, the most sensitive growth stage of barley to drought that Water deficit at this stage caused reduces the fertile florets and thus reduce the number of grains per spike. Drought stress from pollination to maturity stage by intensifying the aging of leaves, reduced growth and reduced grain filling rate is decreased average grain weight and grain yield. This research in order to study the yield of barley genotypes in normal irrigation and drought stress conditions as well as analysis of the relationships between traits and grain yield was conducted. Materials and methods The experimental was conducted under normal irrigation and drought stress conditions during 2013-2014 in a RCB design with three replications in college of agricultural, Shiraz University. The plant material used including eight foreign genotype and two Iranian cultivars (cultivar tolerant of Joseph and Reyhan as susceptible), respectively. All the planting, watering and harvesting, but to be quite similar for both experiments were conducted. In normal condition, plants until the end of the growth phase to field capacity (FC) were irrigated, while in drought stress condition, plants were irrigated to field capacity and then drought stress during flowering size for irrigation was applied. To determine the amount of water required in each irrigation of moisture content in soil was used. At the end of the growth phase and after physiological maturity, plant height, the length of the spike, the number of grains per spike, number of grains per spike, grain weight, grain yield, biological yield and harvest index were measured .Statistical analysis was performed using SAS software MINITAB and averages were compared by Duncan's test at 1%. Results and discussion The results showed that in both drought stress and normal irrigation conditions, there was a significant differences between genotypes in terms of spike length, height, the weight of 1000 grains, grain per spike, spike per meter2, grain yield, biological yield and harvest index. The highest grain yield under irrigation conditions were belonged to genotypes 79, 95 & 120 and Yousef cultivar (with average yield 935.3 g/m2) and under drought stress conditions belonged to genotypes 95 and 120 (average yield 834.3 g/m2).The highest positive correlation under normal irrigation condition belonged to biological yield (0.94), the number of spike & grain per spike (0.51) and under drought stress conditions belonged to biological yield, the weight of 1000 grains and the number of grain with 0.96, 0.65 and 0.63 respectively. In the regression model were important traits under normal irrigation condition, including spike length, biological yield and harvest index with coefficients of determination 0.998, 0.920 & 0.995 respectively, and under drought stress condition, biological yield and harvest index with coefficients of determination 0.935 & 0.995 respectively .Overall under both environmental conditions, the genotypes 95 (with average yield 8809.7 kg/ha-1) and 120 (with average yield 8925 kg/ha-1) as the best genotypes were identified. Conclusion There are significant differences among genotypes for yield components in order to help researchers select for breeding programs could be helpful. Analysis of variance in both normal and drought conditions showed the same traits were assessed. Genotypes in terms of irrigation were significant differences in the characteristics assessed that this proves that the variation between the genotypes under different irrigation.