Evaluation of storage capacity and stem reserves contribution to grain yield of bread wheat affected by terminal drought stress

In order to evaluate the accumulation of dry matter and soluble sugars and their remobilization to the growing grains of wheat cultivars under terminal drought stress, a field experiment was carried out in a split-plot arrangement based on randomized complete block design with three replications during 2009-2010 in Razi University, Kermanshah, Iran. Water regime (includes: complete irrigation (control) and withholding irrigation from starting grain-filling stage till maturity) and wheat genotype (includes: Marvdasht and Pishtaz cultivars and DN-11 and 336 lines) were placed in main and sub-plots, respectively. Under control and drought stress treatments, DN-11 line and Marvdasht cultivar had the highest and the lowest grain yield. Drought stress significantly increased dry mater and soluble sugars remobilization of peduncle and penultimate internode in all genotypes and in 336 and DN-11 lines respectively. 336 and DN-11 lines significantly had higher capacity of stem reserves for remobilization from stem to the growing grains than Marvdasht cultivar (sensitive to drought stress). Among studied internodes, lower internodes in addition to having higher potential for accumulation of photosynthetic material also had higher remobilization rate than penultimate and the peduncle internodes. The evidence from this study suggests that DN-11 line with lower grain loss under terminal drought stress then had the highest drought stress resistance.