The Pattern of Dry Matter Partitioning in Wheat Genotypes under Irrigation and Drought Stress Conditions

Wheat productivity depends not only on dry matter accumulation, but also on its effective partitioning to the grains; this is a key factor to yield stability under stress. The aim of this research was to investigate the pattern of dry matter partitioning to aerial parts in 81 Iranian wheat genotypes differing in agronomic traits. Moreover, its relationship with grain yield in drought conditions was studied. The plant materials were evaluated using two simple lattice designs with two replications under irrigation and drought conditions at University of Tehran Research farm (Karaj) during 2008-2009. Drought stress was imposed by withholding irrigation at the heading stage. Samplings were carried out at anthesis as well as at physiological maturity stages. There was a significant difference between irrigated and drought stress conditions in term of grain yield. Wheat cultivars exhibited diferent responses to drought stress. The rate of reduction in grain yield was variable from 7 to 90 percent. At anthesis, stem, leaf and spike had the highest amount of dry matter, respectively. The effect of stress on dry matter partitioning to different plant parts was not considerable at this stage. In stress condition, a kind of remarkable correlation was observed between grain yield and dry weight of leaf at anthesis. At maturity, spike had the highest amount of dry matter and drought stress decreased dry matter partitioned into spike. But the effect of stress was not considerable on the dry weight of leaf and stem. At maturity, there was a negative correlation between dry weight of stem and grain yield under stress condition.