Effects of seeding rates and panicle nitrogen fertilizer rates on grain yield and quality in good taste rice cultivars under direct sowing

Abstract

<p id="C3">Seeding rate is one of the key factors affecting grain yield under direct sowing in rice, but there are fewer studies of its influence on grain yield and quality in good taste rice cultivars (GTRC). The application of panicle fertilizer is an important measure for high-yielding cultivation in rice production, however, the effects of panicle fertilizer rates on grain yield and quality in GTRC is still unclear. In this study, three representative GTRC (Suxiangjing 3, Nanjing 5055, and Nanjing 9108) in Jiangsu province were used as materials, and the effects of seeding rates (60, 90, 120, 150, and 180 kg hm^-2) and the effect of nitrogen (N) application as panicle fertilizer on grain yield and quality were investigated under direct sowing when the rowing spacing was fixed at 25 cm. The main results were as follows: (1) The yields of Suxiangjing 3, Nanjing 5055, and Nanjing 9108 all increased first and then decreased with the increase of seeding rates. The optimum seeding rates for the high yield of the three rice cultivars were 130.2-136.5 kg hm^-2, 118.3-119.3 kg hm^-2, and 90.0-96.4 kg hm^-2, respectively. Rice processing quality was negatively correlated with the seeding rates to different extents, while chalky grain rate, chalkiness, protein content, and setback was significantly or extremely significantly positively correlated with the seeding rates. Gel consistency, amylose content, taste value, and breakdown were significantly or extremely significantly negatively correlated with seeding rates. (2) Under the optimum seeding rates with the high yield, compared with conventional panicle N application rate, halving the panicle N application had no significant effects on the yields of Nanjing 5055 and Nanjing 9108, but it could significantly improve the appearance quality and taste value. The above results indicated that the optimum seeding rate in GTRC under direct sowing varied with cultivars. Excessive seeding rate would decrease the processing quality, appearance quality, and taste value. Appropriately reducing the amount of N application as panicle fertilizer was beneficial to further improve the appearance and taste quality in GTRC under direct sowing.