Investigation end season drought effect on yield and yield components of ten barley (Hordeum vulgare L.) cultivars in Karaj region

Introduction Barley (Hordeumvulgare) is one of the most important crops in the world. Water deficit at each growth stage of crop leads to a reduction in the different levels of yield. The amount of this decrease depends on many factors such as time, duration and severity of the stress period. Today’s using suitable barley cultivars under drought stress is important in increase economical yield due to the importance of stage of barley under stress, the aim of this study was to investigate the effects of terminal drought stress on yield and yield components of different barley varieties. Matreials and methods This research was conducted in the field of research of Islamic Azad University, Karaj Branch (latitude 35 ° 43'N, longitude 50 ° 49 'East) at the altitude of 11784 m above sea level with an average annual rainfall of 251.2 mm. This site had a clay loam texture. EC, pH and saturated moisture content were 33.3 dS,7.4 and 36%. a split-plot based on randomized complete block design with four replications was carried out. The main plots consisted of two levels: normal irrigation and water stress (irrigation after spike emergence) and subplots including 10 barley cultivars, Valfajar, Basil, Kavir, Zarjoo, Goharjoo, Karoon, Dasht, Turkmen, Nosrat and Yousef. Each experimental plot included 8 sowing lines with a length of 8 meters spacing between lines of 15 cm. 3 meters between main plots and .05 meter between subplot. The first irrigation was carried out immediately after planting. Also, traits such as grain yield, total dry matter, harvest index, 1000 grain weight, number of seeds per spike, number of spikes per unit area, grain weight per spike, plant height and peduncle length were measured. SAS software (V.9) was used to analyze statistics. The comparison of the means was performed using Duncan multiple tests at a significant level of 5%. Results and discussion According to obtained results drought stress caused significant decreasing on grain yield, total dry weight, 1000 grain weight, ear number per unit area, grain weight per ear, plant height and peduncle length and harvest index. Highest grain yield obtained in full irrigation condition relevant to Kavir (7781.5 kg/ha) and Nosrat (7414.8 kg/ha) cultivars also Goharjo cv. in both full irrigation and drought condition produced grain yield 2685.2and 1962.8 kg/ha, respectively.In addition, Kavir cv. with reduction 46.36% and Dasht cv. with reduction, 2.34% of grain yield have highest and lowest sensitivity to drought, respectively. Grain yield showed positive correlation to some traits such 1000 grain weight, ear number per unit area, harvest index, plant height and peduncle length. Also, the highest correlation of grain yield relevant to harvest index (r = 0.74) and total dry matter (r = 0.67), respectively. The cultivar of Dasht had the highest number of spikes per unit area and cultivar GoharJo had the least number of spike per square meter (1181.78, 234.28, respectively). Stress condition had not a significant effect on number of grain per spike, but cultivars had a significant effect on this trait so that the highest number of seeds per spike was shown in Basil cultivar (45.7 seeds) and the lowest of it was shown in Dasht (16.08 seeds). In this regard, the Kavir cultivar has a loss of 36.66% yield in stress conditions and Dasht cultivar have a decreasing of 34.2% with the least susceptibility. Conclusions Kavir cultivar has a reduction of 36.66% of grain yield with the highest susceptibility to stress and cultivar of Dasht have a decrease of 34.2% grain yield and shown the least susceptibility to stress. The highest correlation was observed between grain yield and harvest index (r = 0.74) and total dry matter (r = 0.67).