Comparison of Dry Matter Translocation Efficiency into Grain as Decrescent of Yield Lose under Different Moisture and Nitrogen Regimes in Wheat

ABSTRACT: Stem reserves from pre-anthesis assimilation is the important source of grain filling under stress. In the present study, the main objective was to assess the affect of dry matter translocation efficiency in reduction of yield lose under stress in wheat. Seven wheat cultivars and lines (subplot) grown under well-watered condition (WC), terminal drought stress condition with 30% extra Nitrogen fertilizer (SCN) and terminal drought stress condition(SC) (main plot) in a split plot design. The mobilization efficiency of dry matter was measured in spike, total stem, peduncle, lower internode and leaves and sheath. Spike weight, specific weight of spike and spike length in 15 days after anthesis and in maturity stages were measured. The results showed that genotypes were different in mobilization efficiency of dry matter. Three different environments significantly affected on spike weight and specific weight of spike in maturity . Under SCN, the amount of mobilization efficiency of dry matter in spike, total stem and lower internode increased. It seems that extra N fertilizer lead to increase vegetative growth and reserve accumulation and finally reduce loses of grain yield. As spike weight increased in maturity stage, increase in specific weight represented addition of mobilization of dry matter into spike. Increasing of spike weight in normal conditions (32.3%) and drought/nitrogen conditions (12%) was more than drought conditions (8%). Pishtaz and sepahan varieties showed the highest amounts of mobilization efficiency of dry matter in different parts of plant and also the most ranking of grain yield under three environmental conditions.