| Lodging is one of most important limiting factor in rice cultivation for high yield and good quality, and stability yield. The high yield is base on the biological yield and economic index, which result in the conflicts between high yield and lodging resistant increasingly conspicuous. Therefore, study on the lodging resistance was of great significance. In this study, 5 japonica varieties different in lodging resistance was used to investigate the dynamic change and cultural control during grain filling. The mechanics of lodging resistance, the morphological and physiological difference and dynamic changes of lodging-resistance characteristics during grain filling were detected, which provide the theoretical basis in establishing a cultivation system for lodging resistance and high yield and quality in our study. The results were showed as followed.1 The material dynamic characteristics, including plant height, stem length, 1st base internodes length, 2nd base internodes length, internodes diameter, fresh weight, internodes culms phenotype index the number of large vascular bundles and material dynamic characteristics of physical strength, maximum bearing capacity, breaking resistance, breaking resistance, bending moment, lodging index were different (p<0.01 or p<0.05) in different japonica varieties. The contents of chemical composition in stem and sheath, including potassium (K), silicon(Si), soluble sugar were different significantly. Strong lodging resistance varieties have a relatively short 1st base internodes length, 2nd base internodes length, thick internodes, and more number of vascular bundles. The physical strength and breaking resistance was strong and lodging index was small. Furthermore, the contents of chemical composition and total amount of potassium (K), silicon (Si), soluble sugar were higher.2 The physical strength was negatively correlated(p<0.01) with 1st base internodes length and 2nd base internodes length, the physical strength was positively correlated (p<0.01) with internodes diameter, the number of large vascular bundles, chemical composition contents of potassium(K), silicon(Si), soluble sugar in stem and sheath, while lodging index was negatively correlated(p<0.01).3 The physical strength, maximum bearing capacity of panicle and breaking resistance decreased and the lodging index increased gradually during grain filling and reached a minimum value on ripening stage. On 17-24 days after heading, physical strength, breaking resistance and chemical composition total amount of K, Si, soluble sugars in sheath decreased dramatically. Therefore, about 24 days after heading was a sensitive period of lodging for rice in cold region.4 The analyses of breaking resistance showed that 1st base internodes(N1) > 2nd base internodes (N2)> 3rd base internodes (N3) during grain filling, and lodging index showed that N2>N3>N1. Therefore, lodging internodes of paddy are mainly 2nd base internodes or 3rd base internodes.5 With the increase in fertilizer, plant height and internodes length increased. Internodes diameter, number of vascular bundle, the contents of potassium, silicon and soluble sugar in sheath and stem, stem substantial was decreased, which resulted in the decrease of lodging index and the increase of lodging resistance The application of nitrogen could increase the effective panicles, grain weight , protein content and yield was improved with increased in fertilizer.6 With increase in transplanting density, the internodes length increased, internodes diameter, the number of vascular bundles reduced. The absorption and accumulation of K, Si, soluble sugar content, stem substantial, which resulted in the decrease of lodging index and the increase of lodging resistance. With increase in transplanting density, the effective panicles and grain yield increased. The effect of transplanting density on eating quality was not significant in this study.7 10 days before Jointing, foliar application of "Lifengling" reduced effectively plant height,internodes length and increased internodes diameter, non structural carbohydrates such as soluble sugar and minerals content of potassium and silicon in stem and sheath, increased stem substantial and breaking resistance, enhancing the lodging resistance, and coordination of nutrition. The grain yield was increased with more than 5% and no adverse effects on the grain quality. Furthermore, foliar application of "Lifengling" improved the population structure and relieved the conflict between high-quality cultivation and rice lodging.
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