Ethylenediurea Reduces Grain Nitrogen but Enhances Protein and Carbon Yield in Rice Cultivars

Abstract

Ethylenediurea (EDU) is an indicator of surface ozone (O3), has a high potential to be developed as an applicable protectant for crops against O3 phytotoxicity. Studies on the effects of EDU on grain quality are few, limiting evaluation of the efficiency of EDU protection. In order to understand the effects of EDU on grain quality in rice, a field study was conducted in a rice paddy, where EDU solutions were foliar applied to rice plants. At maturity, grain nitrogen concentrations (GN) in 21 rice cultivars and related traits were analyzed. Mean across 21 cultivars, GN was reduced by EDU by 3.81%, suggesting that O3 in ambient air is affecting grain quality. GN negatively correlated with grain weight and source/sink ratio, but positively correlated with spikelet density. Moreover, GN changes to EDU were rice type dependent, which were −0.43%, −0.72%, and 1.19% in indica, japonica, and hybrid rice, respectively. These results suggest that EDU promotes sink in rice, which helps to increase grain yield, but allocation of nitrogen is not enough to maintain GN in both indica and japonica cultivars. Rice types and cultivars’ variations in the responses of GN to EDU highlight a possibility to adjust grain quality by EDU, combining cultivar selection and agricultural management in response to surface O3 pollution.