The Origin and the History of Main Agronomic Characters of a Paddy-Rice Variety Koshihikari and its Sib Varieties, : II. Varietal differences in grain quality and eating quality

Abstract

Koshihikari, its sister varieties and their pollen parent, Norin 1, were grown under different fertilizer levels at Fukui Agricultural Experiment Station in 1975. Heavy fertilizer application slightly increased the dry matter weight of Norin I in spite of apparent increase in number of tillers and leaf area index. On the other hand, the dry matter weight of Koshihikari and its sister varieties highly increased in the same condition. This difference was caused mainly by the resistance to blast and lodging; Norin I was very susceptible to blast and liable to lodge compared to other varieties. The superiority of these varieties over Norin I was considered as being derived from Norin 22, one of the parental variety. The application of heavy fertilizer lowered brown rice quality and milling percentage. The deterioration of these traits in the sister varieties was much less than that in Norin 1. It was presumed that such a desirable stability in the sister varieties were also inherited from Norin 22. Varietal difference in eating quality became small under the heavy fertilizer condition. Among varieties used, Koshihikari took the first rank in eating quality based on the sensual-test and also in the texturometer value. It can be presumed that Koshihikari accumulated desirable genes concerning eating quality from the ancestral varieties. Protent content of brown rice increased by the application of heavy fertilizer in all the tested varieties. Its rate of increase was high in the high protein varieties. The protein content of Koshihikari was the lowest. Sister varieties. Honenwase and Hatsunishiki, and the parental variety, Norin 1, were ranked in the high protein group. The protein content was not correlated with the cooking quality based on various tests including texturometer test.