Effects of nitrogen fertilization strategies on yield-related traits of rice cultivars with different yield types at panicle development stage

Abstract Rice is one of the most important food crops in the world. About half of the world's people use rice as their staple food. Rice panicle morphogenesis plays an important role in rice yield formation. However, under different nitrogen ( N ) fertilization strategies, it is not clear whether the morphological and physiological state of panicles affects the formation of yield by changing the differentiation and development of panicle. To understand how the panicle differentiation and development, and grain yield are affected by the N fertilization strategies, and clarify the relationship between related traits and yield in the process of panicle development in different varieties. In this study consisted of five N treatments, a panicle weight type (PWT) and a panicle number type (PNT) rice cultivar were grown in the field. The results showed that N fertilization strategies could improve the nitrogen use efficiency and yield of rice, but the response of different rice varieties to N fertilizer strategies was different. The further increase of panicle N fertilizer ratio could not further improve the yield of PNT rice varieties. Correlation analysis showed that SDN and SSR were the main factors affecting yield of DF114. PCA results showed that ZR content in panicle of DF114 was significantly correlated with N concentration in panicle, and was significantly negatively correlated with SRN and RP in floret differentiation stage. ABA content in panicle was significantly positively correlated with SSR in grain filling stage. The floret differentiation of LD11 was the main factor affecting the yield. PCA results showed that IAA in the panicle of LD11 was significantly positively correlated with SDN in the floret differentiation stage. These results suggest that N fertilizer strategies can affect the content of phytohormones in rice at the panicle differentiation stage, and then regulate the differentiation and development of rice panicles to affect yield. It is of great significance to optimize the application mode of N fertilizer according to the characteristics of varieties to improve rice yield and ensure food security.