Effects of terminal drought stress on yield and choosing best tolerance indices in promising lines of Barley

In order to study the effects of terminal drought stress on yield, yield components and drought indices of 19 promising genotypes of barley, two separate experiments in randomized complete block design with three replications was conducted at the Agriculture Research Center of Birjand during 2009-2010 growing season. To enforce drought stress experiment, irrigation stopped after the 50% of heading stage until harvest, and in the normal condition experiment, irrigation followed to the last growth stage. Grain yield, number of seed per spike, grain weight, spike and peduncle lengths and plant height were measured. The reactions of barley lines were different in the two conditions. Drought stress leads to reduction of yield and yield components. Also, MP, GMP, HARM, SSI, TOL and STI indices estimated. Lines No. 11, 13, 15, 18 and 19 were the most tolerant in both control and stress circumstances and lines No. 2, 5 and 7 have a good yield in the control condition. MP, GMP, HARM and STI had a high correlation with grain yield under both conditions, which considering to the correlation between all tolerance indices to drought, were the best indices in both conditions.