Analysis of rice yield formation using the data of the performance test for breeding

Genetic and environmental factors in rice yield formation were analyzed using the data of the performance test for breeding conducted at the NARO Tohoku Agricultural Research Center obtained during a 14-year period. Transplanting and direct seeding with standard fertilization conditions were conducted with the good tasting varieties 'Akitakomachi' and 'Hitomebore', high yielding variety 'Fukuhibiki' and good tasting variety suitable for direct seeding 'Moeminori'. Transplanting and direct seeding with high fertilization conditions were conducted with 'Fukuhibiki' and the large grain high yielding variety 'Bekoaoba'. Although the yield of 'Moeminori' was not significantly different from that of 'Hitomebore' in transplanting, that of 'Moeminori was significantly larger than that of 'Hitomebore' in direct seeding because of less lodging. Although the yield of 'Bekoaoba' was not significantly different from that of 'Fukuhibiki', the average yield for 12 years was 3.4% higher in 'Bekoaoba' than in 'Fukuhibiki' in transplanting with high fertilization. The yield was closely correlated with the number of panicles and total dry weight. The correlation of yield with climate factors; average temperature and sunshine hours in June, July and August were investigated. In three of four varieties in transplanting with standard fertilization, a significant relation was observed between the yield and sunshine hours in Jun. The yield was not clearly correlated with other climate factors. These results suggested that the longer sunshine hours during vegetative growth increased the number of panicles and total dry weight, resulting in a high yield. The generality and specificity of these results need to be examined using the data of a yield test obtained at various places in Japan.