Abstract: To research the tiller emergence frequency of rice cultivars sown directly under aerobic conditions after winter wheat harvest, field experiments were conducted in Mengcheng, Anhui province, in 2005 and 2006. The experiment included two adjacent fields: the submerged and non-submerged field. Five drought resistance rice cultivars were used. They were HanDao502, HanDao297, HanDao277, NingGeng16 and NingGeng35. The aboveground biomass and grain yields of rice cultivars at maturity were 6.3-11.3 t ha-1 and 1.9-5.4 t ha-1 in 2005, 6.6-9.5 t ha-1 and 3.6-4.6 t ha-1 in 2006, respectively. For each cultivar, the differences of aboveground biomass or yield between the non-submerged conditions and the submerged conditions were not significant. Under the both conditions, the tiller emerging potential of HanDao277 was the highest among the cultivars and the contribution of productive tillers to yield was about 50%. Though the tiller emergence frequency of the 3rd to 5th node for Handao502 and Handao297 was high before elongation, most of them were aborted progressively before heading, however. For NingGeng16 and NingGeng35, there were few tillers emerged from the plants before elongation. For all of the cultivars except HanDao277, the contribution of main stems to yield was above 80%.

Key words: aerobic cultivation, Huang-Huai Plain, direct seeding, tiller