Utilization of Low Altitude Remote Sensing to Estimate Canopy Growth and Determine Proper Amount of Top-dressed Nitrogen in a Rice Cultivar “Yamadanishiki” for Sake Brewing

Abstract

Demand of rice grains from the cultivar “Yamadanishiki” for sake brewing is increasing in Yamaguchi prefecture. However, steady supply of high quality grains is still difficult. The objectives of this study are to determine the relationship of output value S1 obtained by proximate remote sensing, with nitrogen accumulation in plants, yield, spikelet number and protein content of brown rice in “Yamadanishiki”. The analysis was carried out in rice fields with different levels of nitrogen fertilization applied at different stages and with different levels of soil fertility in 3 cropping seasons (2016–2018). The nitrogen accumulated in plants, spikelet number, and protein content of brown rice showed a positive correlation with the S1 value. From the correlation, the targeted range of S1 value at full heading was established to control spikelet number and protein content rate at proper levels. The S1 value at full heading increased with increase of nitrogen fertilizer at the panicle formation stage. Therefore, the target S1 value at full heading could be achieved by measuring the S1 value at the panicle formation stage, and by calculating and applying the proper amount of nitrogen fertilizer.