A dynamic model and its characteristics for nitrogen accumulation after transplanting in medium-maturity types of Yongyou <italic>japonica/indica</italic> hybrids

Abstract

<p indent="0mm">In order to quantitatively describe the dynamics of nitrogen accumulation after transplanting of medium-maturity types of Yongyou <italic>japonica/indica</italic> hybrids (MJIH), and to elucidate the mechanism of high yield based on modelling methods, MJIH Yongyou 2640 and Yongyou 1640, <italic>japonica</italic> conventional rice (JC) Yangjing 4038 and Yangjing 4227, and <italic>indica</italic> hybrid rice (IH) Xinliangyou 6380 and Yangliangyou 6 were used to compare the differences in nitrogen uptake characteristics after transplanting in 2015 and 2016. Grain yield of MJIH averaged <sc>11.65 t</sc> hm^–2 across two years, significantly higher than JC <sc>(10.74 t</sc> hm^–2) and IH <sc>(10.01 t</sc> hm^–2). Similar trends were also observed in nitrogen accumulation amount at maturity and nitrogen accumulation per <sc>100 kg</sc> grain. For MJIH, the nitrogen accumulation and its ratio to total nitrogen accumulation at maturity was the highest in panicle, the medium in leaf, and lower in stem. For JC and IH, the nitrogen accumulation and its ratio to total nitrogen accumulation at maturity was the highest in panicle, the medium in stem, and lower in leaf. Compared with JC and IH, MJIH had higher ratio of leaf nitrogen accumulation, while lower ratio of panicle nitrogen accumulation to total nitrogen accumulation at maturity. There was a good fitness between Gompertz equation and dynamics of nitrogen accumulation of rice varieties in our study. Compared with JC and IH, MJIH had higher nitrogen accumulation amount in the early, middle and late nitrogen accumulation stages, which was due to long time of accumulation and higher accumulation rate in the middle stage, and higher nitrogen accumulation rate in the early and late stages. This study applied Gompertz equation to simulate the dynamics in nitrogen accumulation after transplanting of different rice varietal groups, and analyze the superiority of nitrogen accumulation of MJIH based on Gompertz equation.