Dry Matter Accumulation and Partitioning in Wheat Genotypes as Affected by Sowing Date Mediated Heat Stress

Dry matter accumulation and its partitioning to grain are important factors which directly or indirectly affects the grain yield. Heat stress during grain filling period of wheat negatively effects the dry matter produc- tion of wheat genotypes. Delay in sowing date significantly reduces the dry matter accumulation of wheat genotypes at anthesis as well as maturity. Grain yield was positively correlated with dry matter at maturity (r = 0.640 and r=0.584 timely and late sown re- spectively) indicating that plant dry matter is important for grain formation and grain filling in wheat genotypes. At maturity, timely sown genotypes had more percentage of dry matter partitioned to grain as compared to late sown genotypes. High yielding genotypes showed more dry matter accumulation in grain whereas low yielding genotypes retained much dry matter in stem, leaves and chaff. This reduction in dry matter accumulation in grain may be attributed to high temperature stress faced by late sown genotypes during their grain filling period.