Effects of precision rice hill-drop drilling on rice quality

Grain qualities including milling, appearance, cooking and nutritional quality, are important traits that have aroused rice researchers' attention worldwide. Head rice rate, an important milling quality together with grain yield affects head rice yield. The head rice yield is directly related to economic value of the grains, and has significant impacts on income of rice producers. Precision rice hill-drop drilling is a simplified technique, which can achieve high yield while is applied at appropriate rice growth regions. The precision rice hill-drop drilling technique has been applied in many rice growth regions in China. Previously, precision rice hill-drop drilling technique has been proven to influence rice yield, agronomic performances and grain qualities in small region only and assessing the effect of precision rice hill-drop drilling technique on grain qualities in national wide is therefore important. In order to investigate the influence of precision rice hill-drop drilling technique on grain qualities in multiple rice growth regions in China, the comparison experiment were carried out. In this study, comparisons of the grain qualities between precision rice hill-drop drilling and machanical transplanting were investigated in the mainly planting areas (viz: Anhui, Shanghai, Guangdong, Sichuan, Xinjiang and Shandong) of precision rice hill-drop drilling in China. Results showed that precision rice hill-drop drilling technique was beneficial to improve head rice yield. Rice by using precision rice hill-drop drilling had higher head rice yield than that by using machanical transplanting in Nanling Anhui, Mianzhu Sichuan, Wensu Xinjiang, and Gaoqing Shandong regions, which increased by 9.11%, 27.02%, 4.08%, and 11.11% significantly. Moreover, the effects of precision rice hill-drop drilling technique on protein content and amylose content in grains from different investigated regions were different because of the difference in cultivars and environmental conditions，and the decrease in protein content and amylose content in grains were detected for some investigated regions. Furthermore, precision rice hill-drop drilling technique significantly decreased chalky rice rate in grains in Gaoqing Shandong, while showed no significant effect on appearance qualities of grains for other investigated regions. This study have investigated the impact of precision rice hill-drop drilling technique on grain quality of the rice varieties planted in large areas of the rice planting regions in China, this work is beneficial to further promotion to the popularization and application of precision rice hill-drop drilling technique in appropriate areas.