氮肥水平和栽插密度对杂交稻茎秆理化特性与抗倒伏性的影响

以杂交稻金优527为材料，分别在中低海拔地区雅安(600 m)和高海拔地区西昌(1 590 m)进行了以氮肥水平为主区，栽插密度为副区的田间裂区试验。结果表明,随施氮量和栽插密度的增加，茎秆基部节间变细长，茎壁变薄，秆型指数降低，茎鞘中淀粉、纤维素、木质素含量降低，充实度变差；氮肥水平和栽插密度还影响茎秆中氮、钾、硅、钙、镁、铁、锌、铜、锰等矿质元素的含量，从而影响茎秆的倒伏指数和抗倒伏能力。水稻基部茎秆的倒伏指数与株高、重心高度和基部各伸长节间的长度及氮、镁含量正相关，与茎粗、茎壁厚、比茎重、秆型指数及淀粉、纤维素、木质素和钾、钙含量负相关，与茎秆硅含量呈二次函数关系，适宜的硅含量为4.5~4.8 mg kg^-1。由于生态条件不同，两试点水稻茎秆抗倒能力和受氮肥水平与栽插密度影响的程度存在一定差异，高产、抗倒栽培要因地制宜。金优527基部节间的临界倒伏指数为200。

Effects of Nitrogen Rate and Transplanting Density on Physical and Chemical Characteristics and Lodging Resistance of Culms in Hybrid Rice

There have been a lot of studies onthe differences and variations in lodging resistance among different rice varieties, but few studies involving the combined effects of nitrogen rate and transplanting density on lodging resistance of a certain hybrid varieties at different planting areas. In order to study the relationship between lodging resistance and physical and chemical characteristics of rice culm and the effects of nitrogen rate and transplanting density on the physical and chemical characteristics and lodging resistance of hybrid rice culm, a split plot field experiment was conducted with hybrid rice Jinyou 527 at Ya’an which altitude is about 600 m and Xichang which altitude is about 1 600 m. The experimental results were as follows. With the increasing of nitrogen rate and transplanting density, the plant height and length of basal internodes increased, the diameter of stem and the wall thickness of culm reduced, and the culm phenotype index decreased. High nitrogen rate and planting density lowered the contents of starch, cellulose and lignin of culm. The contents of N, K, Si, Ca, Mg, Fe, Zn, Cu, and Mn of culm were also influenced by nitrogen rate and transplanting density. As a result, high nitrogen rate and transplanting density reduced the breaking strength and lodging resistance of rice culm. The lodging index positively correlated to plant height gravity center height, length of basal internodes and contents of N and Mg, and negatively correlated to diameter of stem, wall thickness of culm, ratio of weight to length of stem, culm phenotype index, contents of K, Ca and starch, cellulose, lignin of culm. However, the relationship between lodging index and Si content of culm was quadratic function. The optimum Si content for high lodging resistance of rice culm was 4.5–4.8 mg kg^-1. There were some differences in lodging resistance and sensitivities to nitrogen rate and transplanting density between Ya’an and Xichang, so the suitable techniques for high yield and high lodging resistance of culm should depend on the planting area. It was found that the critical lodging index for hybrid rice Jinyou 527 was 200.