Impact assessment of the varieties and cultivation methods on paddy yield: Evidence from a large-scale farm in the Kanto region of Japan

This study aims to identify the impact of variety and cultivation method to paddy yield within the largescale farms, which have been increasing over the latest decades in Japan. The study objects are 351 paddy fields in a farm corporation over 113 ha, locating in the Kanto region of Japan, and the yield is measured by smart combine. The result of ANOVA (Analysis of Variance) indicates that variety of paddy is a significant factor affecting the yield; although the cultivation method is not significant, it is significant interacting with the effect of variety. According to the result of Duncan's new multiple range test (DNMRT), the varieties are divided into three groups. Further analyses with the adoption of four factors and results of the following ANOVAs show that time of transplanting or sowing, growth duration from transplanting or sowing to earring, total Nitrogen amount and field area are effective factors. Finally, the key points for higher paddy yield are summarized, including suitable variety adoption, earlier transplanting or sowing and hence longer period for vegetative accumulation, sufficient Nitrogen application, and appropriate field areas.