Effects of Soil Drought on Accumulation and Remobilization of Stem Reserves in Wheat

Under rain-proof shelter culture condition,two types of winter wheat(Triticum aestivum.L),dryland cultivar Changwu 134(drought-resistant) and irrigated cultivar Shaan 253(drought-sensitive),were applied to study the effects of soil drought on post-anthesis dry matter accumulation,remobilization and contribution to grain yield of stems and their constituent internodes.The result indicated that the dry matter accumulation of main stem and constituent internodes,accumulation amount and accumulation rate of main stem spike during the middle and later grain-filling period decreased significantly as a result of soil drought,but the extent of reduction in Changwu134(except other internodes) was much less than that of Shan253.The dry matter remobilization that accumulated at the main stem could not compensate for the loss of grain yield.However,a close relationship was found between accumulation amount of main stems pike and reserves remobilization amount as well as the remobilization rate of the other internodes under soil drought condition.The extent of reduction in dry matter remobilization amount and remobilization rate of other internodes of drought-resistant wheat were significantly higher than those of drought-sensitive wheat,which directly resulted in a significant decrease in the contribution rate to grain yield of main stem of drought-resistant wheat.