Effects of simultaneous furrow ridging and precision hill-direct-seeding on grain yield and quality of double-cropping indica rice in South China

This study aims to investigate the effects of different direct seeding methods on the yield and rice quality of early-late season double-cropping indica rice in south China. Taking the Xiangzaoxian45 (inbred indica rice) and Taiyou398 (hybrid indica rice) as the research materials in both early and late seasons, two direct seeding methods were set, including artificial seeding (AS), and precision rice hill-drop drilling machine (PHDD), to determine the yield and its components, emergence rate of seedlings, and quality of rice grain for the direct-seeded indica rice in a typical double cropping area for the early-late season. The results showed that the PHDD significantly increased the emergence rate of seedlings and grain yield of tested varieties, with the increasing rates of 7.4%-14.2% and 6.9%-8.0% in early season and late season, respectively, compared with AS. The PHDD was beneficial to increase the annual yield of tested varieties, with the range of 3.23%-21.66%. Specifically, the Xiangzaoxian45 increased significantly grain yield in the early and late season, while the Taiyou398 increased significantly in the late season. In terms of yield components, the increase in grain yield of tested varieties under the PHDD was mainly due to the relatively obvious achievement of effective panicles and grain number per panicle. Besides, the PHDD significantly increased the milled rice rate, head rice rate, and chalkiness degree in the early season of Xiangzaoxian45, while the chalkiness ratio in the late season of Taiyou398, but significantly decreased the head rice rate in the early season of Taiyou398, while the chalkiness degree, chalkiness ratio, and the protein content in the late season of Xiangzaoxian45. However, there was no significant difference in the amylose content of tested varieties. Meanwhile, the PHDD significantly increased the peak viscosity, hot paste viscosity, breakdown value, and final viscosity of Taiyou398 in late-season rice flour, whereas, significantly reduced the gelatinization temperature. The PHDD can contribute to improve the annual yield of high-quality rice varieties, which was mainly related to the coordination of panicles ratio and grain number per panicles. Nevertheless, the ways to increase production varied with the tested varieties and growing seasons. Specifically, the PHDD significantly improved the early season processing quality and late-season appearance quality of Xiangzaoxian45, while decreased the early season processing quality and late-season appearance quality of Taiyou398, but improved its cooking and eating quality in the late season. The quality of direct seeding rice in the late season was enhanced obviously under the PHDD regime. The finding can provide a theoretical basis for high yield and high-quality cultivation of double-season direct-seeding indica rice in South China.