Morphogenesis of ratoon crops in response to preharvest nitrogen application in japonica rice

Abstract

Context

Nitrogen (N) application during grain filling of the main crop increases yield of ratoon rice. However, the morphological development of ratoon crops in response to preharvest N management is not well documented.

Objective

We hypothesized that plant N nutrition during grain filling of the main crop mediates the morphogenesis of ratoon tillers and panicles. Our objective was to elucidate the morphological characteristics by which preharvest N promotes ratoon crop growth.

Methods

Two N treatments were compared in a lowland rice field for 2 years: with or without 60 kg N ha^–1 applied at 5 days after heading of the main crop. The lengths of the tiller buds and young panicles at each node of the ratoon crop were monitored by dissecting the stubble. Logistic functions simulated the ratoon development dynamics.

Results

Preharvest N application increased ratoon crop yield by enhancing ratooning ability. It also advanced the onset of ratoon tiller growth and shortened the development period of tiller buds and young panicles at the upper nodes. In contrast, ratooning ability and ratoon crop growth at lower nodes were not affected.

Conclusion

Increased ratoon crop yield after preharvest N application resulted from advanced ratoon development and enhanced ratooning ability at the upper nodes.

Implications

This study provides scientific support for the importance of preharvest N application in ratoon rice cultivation. Our findings will contribute to improvement of N management in riceratoon-rice systems.