Lodging Resistance of <i>Japonica</i> Hybrid Rice Plants Studied in Relation to Mechanical and Physicochemical Characteristics

The research on rice lodging resistance holds immeasurable value for achieving high yield, stable production, and superior quality of rice. To investigate the effects of mechanical properties and physicochemical characteristics of <i>Japonica</i> hybrid rice on its lodging resistance ability under natural field cultivation conditions, <i>LY1052</i>, <i>LY9906</i>, and <i>GY1</i>, which were mainly popularized in northern China, were selected as the experimental subjects, and <i>NL313</i>, <i>Japonica</i> hybrid rice prone to lodging, was taken as the control (<i>NL313</i>).The max bending force, breaking moment, bending section coefficient, single stem weight mass moment, bending strength, Young’s elastic modulus, inertia moment, and other mechanical indexes were measured by the bending test and tensile test, and the correlations between mechanical indexes, physicochemical indexes, and lodging index were studied. There was an extremely significant difference in the lodging index of experimental subjects and control (<i>NL313</i>) (<i>p</i> < 0.05). Therefore, it was concluded that the lower plant height and lighter panicle were not the stronger lodging resistance under appropriate cultivation conditions. Optimization of rice plant-type structure can achieve the unity of high culm and high yield. The lodging resistance of rice could be improved by shortening the internode length, increasing the tissue thickness and vascular bundle area, and increasing the content of cellulose and potassium in the stem. It was also found that the lodging resistance of rice plants was positively correlated with the maximum stem bending force, breaking moment, bending section coefficient, bending strength, and Young’s elastic modulus (<i>p</i> < 0.01) and negatively correlated with single stem weight mass moment and inertia moment (<i>p</i> < 0.01). It is feasible to select them as reference indexes of the lodging resistance of rice. The experimental results not only help to enrich the theoretical system of rice lodging resistance research but also provide an essential reference and basis for formulating scientific cultivation and management measures and breeding lodging-resistant rice varieties in practical production, which is of great significance for ensuring global food security and promoting sustainable agricultural development.