Dry Cultivation of Rice (Oryza sativa L.) Enhances Drought Resistance by Modulating Root System Architecture, Antioxidant Potential and Sugar Metabolism

Abstract

Rice is one of the world's major staple crops. Against the balance of population growth and water scarcity, improving drought resistance and yield of rice is essential for food security. However, the understanding remains limited regarding photosynthesis, antioxidant mechanisms and carbohydrate partitioning in the leaves and roots of rice under drought conditions. Based on our previous findings, this study compared the drought-resistant variety (Changjing616, CJ) and the drought-sensitive variety (Lianyu1013, LY) under flooding and dry cultivations. Our results revealed that CJ maintained comparable yields to those under flooding cultivation, whereas LY experienced a significant decline in yield. Furthermore, we demonstrated that CJ sustained a higher photosynthetic rate and enhanced the activities of antioxidant enzymes under dry cultivation. In terms of root morphology, CJ showed significant improvement in key growth parameters under dry cultivation, while LY demonstrated a significant decline in these characteristics. The sugar contents and the activities of related enzymes in both the leaves and roots of CJ were notably enhanced by dry cultivation. Notably, the correlations between root systems and sugar metabolism varied between the two cultivation methods. In addition, the study identified that the increased R/S ratio, resulting from alterations in sugar metabolism under dry cultivation, significantly contributed to the drought resistance of rice. Collectively, these findings elucidate the pivotal role of sugar metabolism in enhancing the drought tolerance of rice under dry cultivation practices.