HIGH-YIELDING PERFORMANCE OF PADDY RICE A CHIEVED IN YUNNAN PROVINCE,CHINA .1. HIGH-YIELDING ABILITY OF JAPONICA F1-HYBRID RICE, YU-ZA-29

Rice seedlings of cultivar Yu-Za 29 were planted by the conventional c ultivation method with a planting density of 78.5 hills per m(2) (dens e planting) in Binchuan, Yunnan Province and achieved a paddy yield of 1,664 gm(-2), the sampling area being 700 m(2). In addition, a very h igh paddy yield of 1,982 gm(-2), the sampling area being 6 m(2) in tot al of three sub-plots, was recorded by reducing the planting density t o about half of the conventional one (42.7 hills per m(2), sparse plan ting). The average daily incident solar radiation during whole growing period (19.3 MJ m(-2) d(-1)) was about 20% higher compared to the mea n value (16.1 MJ m(-2) d(-1)) obtained in the five-year experiment of the Japanese International Biological Program (JIBP). On the other han d, the efficiency for solar energy utilization (Eu) of Yu-Za 29 for bi ological production during the whole growth period was higher by 28-50 % in comparison with the average Eu (1.25%,) of the five-year experime nt of JIBP. Eu for grain production exceeded the highest Eu (059%) in the JIBP by 17-49% In Yu-Za 29, the harvest index was estimated at mor e than 0.6 for top-dry weight over 2,500 gm(-2) and the grain-straw ra tio reached more than 1.4 for straw weight over 1,180 gm(-2). The spik elet number per m(-2) was 71,000 to 87,700 and the filled-spikelet per centage was 76.0 to 76.2%. An increase in both components of dry-matte r production and the partition ratio of dry matter to grains as well a s the high percent of the filled spikelets, regardless of a very large number of spikelets, had been attained with the sparse planting compa ring with dense planting. Key wards:China, High yield, Paddy rice, Sol ar radiation, Yunnan Province, Yu-Za 29.