The objective of this study was to investigate whether and how exogenous abscisic acid(ABA)is involved in mediating starch accumulation in the grain and redistribution of carbohydrates during grain filling of two wheat cultivars with different staygreen characteristics.At blooming stage,plants of Wennong 6(a staygreen cultivar)and Jimai 20(control)were sprayed with10 mg L-1abscisic acid(ABA)for 3 days.The application of ABA significantly(P<0.05)increased grain filling rate,starch accumulation rate and content,remobilization of dry matters to kernels,and 1000-grain weight of the two cultivars.Exogenous ABA markedly(P<0.05)increased grain yield at maturity,and Wennong 6 and Jiami 20 showed 14.14%and 4.86%higher compared yield than the control.Dry matter accumulation after anthesis of Wennong 6 was also significantly(P<0.05)influenced by exogenous ABA,whereas that of Jimai 20 was unchanged.Application of ABA increased endogenous zeatin riboside(ZR)content 7 days after anthesis(DAA),and spraying ABA significantly increased endogenous indole-3-acetic acid(IAA)and ABA contents from 7 to 21 DAA and decreased gibberellin(GA3)content at 14 DAA,but increased GA3content from 21 to 35 DAA.The results suggested that increased yield of staygreen was due to greater starch assimilation owing to a higher filling rate and longer grain-filling duration. The objective of this study was to investigate whether and how exogenous abscisic acid (ABA) is involved in mediating starch accumulation in the grain and redistribution of carbohydrates during grain filling of two wheat cultivars with different staygreen characteristics. At blooming stage, plants of Wennong 6 (a staygreen cultivar) and Jimai 20 (control) were sprayed with 10 mg L -1 abscisic acid (ABA) for 3 days. The application of ABA significantly (p <0.05) increased grain filling rate, starch accumulation rate and content, matters to kernels, and 1000-grain weight of the two cultivars. Exogenous ABA markedly (P <0.05) increased grain yield at maturity, and Wennong 6 and Jiami 20 showed 14.14% and 4.86% higher than yield than the control. after anthesis of Wennong 6 was also significantly (P <0.05) influenced by exogenous ABA, whereas that of Jimai 20 was unchanged. Application of ABA increased endogenous zeatin riboside (ZR) content for 7 days after anthesis (DAA), and sp raying ABA significantly increased endogenous indole-3-acetic acid (IAA) and ABA contents from 7 to 21 DAA and decreased gibberellin (GA3) content at 14 DAA, but increased GA 3 content from 21 to 35 DAA.The results suggested that increased yield of staygreen was due to greater starch assimilation owing to a higher filling rate and longer grain-filling duration.