Abstract: To explore the reasons for the large biomass and strong stress resistance but no outstanding yield advantage of japonica hybrid rice, 140 hybrid combinations of japonica hybrid rice, which were cross-fertilized from 140 restorer lines and BT-type cytoplasmic male sterility (BT-CMS) line Liao-99A, were used to examine dry matter accumulation, transportation and their relationships with yield under two fertilization treatments: normal fertilization (including basic fertilizer, tillering fertilizer and spike fertilizer) and low fertilization (including basic fertilizer only). The results showed that lower seed setting rate and 1000-grain weight were the most important factors limiting the yield advantage of japonica hybrid rice. The yield of japonica hybrid rice was more dependent on dry matter accumulation after full heading stage. Under the low fertilization treatment, dry matter export percentage from stem and sheath increased and that from leaf decreased. Reducing the export percentage of dry matter accumulation in stem and increasing that in leaf were beneficial to decrease the yield discrepancy under different fertilizer treatments and promote the superiority of japonica hybrid rice in tolerating low-fertility. Our results could provide important insights in the selection of resistance breeding of japonica hybrid rice.

Key words: tillage, soil aggregation, microbial diversity, PCR-DGGE.