Effects of integrated nutrient management on lodging resistance of rice in cold area.

【Objective】 The relationship between integrated nutrient management and the lodging resistance of rice was studied to elucidate the mechanism underlying the lodging resistance of rice plant in cold area. 【Method】 A field experiment was conducted with 4 nutrition managements and the physical properties, mechanical features and carbon-nitrogen ratio of the stems of rice were analyzed. 【Result】 The yield of the farmers fertilization practice (FFP) was 8.55 t·hm-2. Optimal fertilization practice (OPT) increased the yield, reduced the length of the first and second internode of the basal stem by 11.6% (P5%), 13% and 6% (P 5%), respectively, significantly increased carbon-nitrogen ratio, stem diameter, stem wall thickness, leaf sheath weight and area of cross section 30 d after heading, and reduced the index of lodging resistance by 14.18% (P5%). Compared to FFP, the yield of the farmers fertilization practice for high yield (FFP -H) was increased by 15.2% and achieved high-yield rice. Compared to FFP-H, the optimal fertilization practice for high yield (OPT-H) increased rice yield by 7.4%, the length of the first and second internode of the basal stem is reduced by 12% and 4% (P5%), separately, at the same time, carbon-nitrogen ratio, stem diameter, stem wall thickness, leaf sheath weight and area of cross section were significantly increased, and the index of lodging resistance was reduced by 6.19% (P5%) 30 d after heading. Compared to OPT, the harvest panicles of OPT-H was increased by 15.1% (P5%), yield was increased by 10.9% (P5%), but the index of lodging resistance between the two treatments was not significanty different. 【Conclusion】 OPT and OPT-H increased the height of gravity center and plant height, but reduced the distance of basal internode due to optimization of internode collocation of rice, and increased carbon-nitrogen ratio of rice stems and stem diameter, promoted stem substantiality, resulting in high grain yield and lodging resistance of rice plant.