Increasing the Brown Rice Yield of Palatable Cultivar “Yamadawara” to over 800 g m^–2

Abstract

The food-service industry demands inexpensive and palatable rice. The cultivar “Yamadawara” produces high yields of palatable rice, thereby satisfying this demand. To clarify the requirements for high yields (above 800 g m^–2) of brown rice in “Yamadawara”, we examined the effects of nitrogen application on yield in different growth seasons. Increasing nitrogen application levels led to a significantly higher yield in 2016 but had no significant effect in 2015. Nitrogen application led to significantly higher spikelet number per area in both years. Therefore, the difference in yield response with the year was attributed to spikelet maturation. Solar irradiation during the first part of the maturation period (until 20 days after heading) had a significant positive correlation with yield. However, the mean temperature during the same period had a significant negative correlation with appearance quality. Based on these results, we concluded that the requirements for obtaining a yield above 800 g m^–2 in “Yamadawara” were (1) heading between 9 and 15 August in Fukuyama, and (2) application of nitrogen fertilizer sufficient to produce 41,000–45,000 spikelets m^–2.