Suitable Levels of Grain Yield and Yield Components of “Akebono”, a Rice Cultivar Mainly Produced for the Food Service Industry

Abstract

The farmers who must meet the demands of the food service industry for less expensive rice, while securing their income, need a technique for high and stable yield. To clarify the suitable yield level of a cultivar “Akebono” for the farmers, I examined grain yields, yield components, lodging indices and inspection grades of grain quality, under several different amounts of fertilizer application in Okayama prefecture, Japan, for three years. Both in 2016 and in 2017, grain yield reached 700 g per m² without heavy lodging in one experimental plot, but not in 2018 when sunshine was lacking during the maturing stage. In order to reach this yield level, approximately 33000 spikelets per m² was required, and the percentage of ripened grains had to be kept above 86%. On the other hand, increase in the number of spikelets per m² above 33000 led to a higher risk of heavy lodging and poor grain quality. Therefore, I concluded that the suitable level of grain yield was 700 g per m² for “Akebono”. A new technique needs to be developed to produce constantly 33000 spikelets per m² and keep the percentage of ripened grains above 86%.