Relationship between leaf color change and ammonia volatilization in rice during grain filling

The objective of this study was to determine whether leaf color change in rice plants predicts ammonia (NH₃) volatilization during the late grain-filling period. In a pot study of indica and indica–japonica hybrid cultivars, the leaf color-changing rate was highly significantly positively correlated with NH₃ volatilization during the grain-filling stage. Cultivars with fast leaf color-changing had higher NH₃ volatilization loss due to their higher apoplastic NH₄⁺ concentration and NH₃ compensation point, along with lower glutamine synthetase (GS) activity. N application, although it delayed leaf color change, led to increased NH₃ volatilization. Selecting cultivars with slow leaf color-changing characteristics and managing fertilization to delay the leaf color change process could reduce N gas loss and increase N use efficiency.