Effects of one-time nitrogen basal application on the yield and quality of different direct-seeding rice crops by machine

Abstract: This study aims to explore the light, simple, and efficient production way for one-time basal application of nitrogen fertilizer in the whole process of high-quality eating rice under different types of mechanical direct seeding. The field experiment was conducted in 2018 and 2019 at an agriculture experiment station in Jiangyan District of Jiangsu Province, China. The material was used as the late-maturing medium japonica high quality rice variety Nanjing 9108. Two formulas of controlled-release available nitrogen fertilizer were set under the water and dry direct seeding: controlled-release-available nitrogen fertilizer formulation A basal application(T1), controlled release-available nitrogen fertilizer formulation B basal application(T2), and the application of common urea in several times as the control(CK). An investigation was made to clarify the effects of one-time nitrogen basal application on the rice yield and quality under two mechanical direct seeding. The results showed that the rice yield reached 9.0×103 kg/hm2 in the controlled release-available nitrogen fertilizer formulation, beyond that in various direct seeding. In water direct seeding, the yield of water direct seeding rice was ranked from large to small, CK, T1, and T2, indicating no significant difference between CK and T1. In dry direct seeding, the rice yield of dry direct seeding was ranked in a descend order: CK, T2 and T1, indicating no significant difference between CK and T2. The rice yield in a water direct seeding was larger than that of a dry direct seeding. In terms of quality, compared with CK, the controlled release-available nitrogen fertilizer treatments significantly improved the rice processing and nutritional quality, where the head milled rice rate and protein content increased by 5.79%-12.21% and 1.18%-3.86%, respectively, and chalkiness increased by 0.16%-15.12%, but the appearance quality became worse, and the amylose content decreased by 1.14%-5.12%. There was no significant difference in the taste value of dry direct seeding among treatments, or the water direct seeding between T1 and CK, but significantly higher than that of T2. In the RVA profile for the controlled release-available nitrogen fertilizer formulation, peak viscosity, trough viscosity, final viscosity, and breakdown were lower than those in CK, while, the setback and consistence were higher than those of CK. There was no significant difference in the rice processing and appearance quality among direct seeding. The amylose content was larger in the water than that in the dry direct seeding. The protein was higher in the dry direct seeding than that in the water direct seeding, indicating there was no significant difference in taste value. In the RVA profile, the water direct seeding was significantly higher than dry direct seeding in breakdown (P<0.05), indicating the dry direct seeding significantly better than the water direct seeding in setback value (P<0.05). One-time basal application of controlled release-available nitrogen fertilizer formulation A in the water direct seeding and formulation B in dry direct seeding can achieve the stable rice yield, and high quality of rice, indicating a great reduction of fertilization frequency. The finding can be beneficial to simplify the production of high quality, stable yield, and high efficiency of mechanical direct seeding rice.