High-Yielding Performance of Paddy Rice Achieved in Yunnan Province, China. I. High yielding ability of Japonica F1 hybrid rice, Yu-Za 29.

Abstract

Rice seedlings of cultivar Yu-Za 29 were planted by the conventional cultivation method with a planting density of 78.5 hills per m2 (dense planting) in Binchuan, Yunnan Province and achieved a paddy yield of 1, 664 gm-2, the sampling area being 700m2. In addition, a very high paddy yield of 1, 982 gm-2, the sampling area being 6m2 in total of three sub-plots, was recorded by reducing the planting density to about half of the conventional one (42.7 hills per m2, sparse planting). The average daily incident solar radiation during whole growing period (19.3 MJ m-2 d-1) was about 20% higher compared to the mean value (16.1MJ m-2 d-1) obtained in the five-year experiment of the Japanese International Biological Program (JIBP). On the other hand, the efficiency for solar energy utilization (Eu) of Yu-Za 29 for biological production during the whole growth period was higher by 28-50% in comparison with the average Eu (1.25%) of the five-year experiment of JIBP. Eu for grain production exceeded the highest Eu (0.59%) in the JIBP by 17-49%. In Yu-Za 29, the harvest index was estimated at more than 0.6 for top-dry weight over 2, 500gm-2 and the grain-straw ratio reached more than 1.4 for straw weight over 1, 180 gm-2. The spikelet number per m-2 was 71, 000 to 87, 700 and the filled-spikelet percentage was 76.0 to 76.2%. An increase in both components of dry-matter production and the partition ratio of dry matter to grains as well as the high percent of the filled spikelets, regardless of a very large number of spikelets, had been attained with the sparse planting comparing with dense planting.