Abstract
A Chinese high-yielding large-panicle indica cultivar Yangdao 4 (YD) was examined for the response of yielding ability, sink size and percentage of filled grains (PFG), to the cultivation practice in comparison with a Japanese cultivar Hinohikari (HH) that had almost the same growth duration in 2005 and 2006. Treatments included planting density and number of seedlings hill-1, and supplement application of fertilizer to deep layer (SAFDL). Results revealed that the average sink size of YD was 17−28% larger than that of HH due to the larger number of spikelets panicle-1 and heavier grain weight. A significantly larger sink size was attained by the high density planting and SAFDL treatments in both cultivars, but not by changing the seedling number hill-1. The sink size of YD responded more significantly to the cultivation practices than that of HH. The average PFG in YD was about 10% higher than that in HH in both years. The PFG in both cultivars decreased with increasing sink size, but the decreasing rate in YD was 1/3 of that in HH and its yearly fluctuation was also less in YD than in HH. Consequently, the yield of YD increased with increasing sink size in contrast to HH. The average brown-rice yield of YD (640−653 g m-2) was 41−51% higher than that of HH (418−454 g m-2). In comparison with HH, the stable PFG in YD at increased sink size could be attributed to the increase of carbohydrate accumulation in the panicle (ΔW+ΔT ), larger amount of NSC in the LS+C and higher NSC/sink size.
