Abstract
In this study, the influences of environmental conditions on the protein content of grain at different positions within a rice panicle were studied. The protein content of basal spikelets (BS) was higher than that of terminal spikelets (TS) and that of spikelets in the middle position on a panicle (SM) under all the environmental conditions studied. BS, TS, and SM produced in the lodging plot had the highest protein content, and BS, TS, and SM produced in the non nitrogen fertilizer plot had the lowest. BS showed a larger variation in the protein content (4.1%) than TS (2.2%) and SM (3.2%) did. Among BS, SM, and TS, there was an inversely proportional relationship between the protein content and the crude grain weight, and a proportional relationship between the amount of protein in a grain and the crude grain weight. Therefore, the high protein content of spikelets with low grain weight could be due to the deficiency of starch accumulation in rice endosperm as shown by the decrease in the amount of protein. It was concluded that variations in the protein content within a rice panicle were caused by the diffrerences in the crude grain weight, which was closely related to the flowering order of spikelets.
