中文摘要：

【目的】针对大豆产量提升过程中随种植密度增加而引发的倒伏问题,开展不同群体结构下,大豆植株抗倒性状的综合比较研究.【方法】以大豆新品种吉农30和吉农40为材料,通过设定5个种植密度,研究茎秆及根系的抗倒机制.【结果和结论】种植密度改变了群体的内部结构,随着密度的增加,倒伏逐渐加重且与低密度差异显著.高密度群体结构下,节间长度增长趋势较低密度明显、低节位单位茎长鲜质量小于高节位,而低密度下则表现相反;随密度增加,低节位茎粗、节间鲜质量降低幅度较高节位明显.可见,茎秆1-5节的物质分配发生了变化,这些性状的改变削弱了植株的抗倒能力.茎秆抗倒性状表现为：茎秆压碎强度、抗倒指数、单位茎长鲜质量随密度增加显著降低,与倒伏呈极显著负相关;而株高/茎粗、重心高度、节间长度显著增加,与倒伏呈极显著正相关.地下部根系的根瘤数、根干质量和伤流量等随密度的增加而逐渐降低,与倒伏呈负相关,其中倒伏级数与伤流量、根干质量相关系数最高,达极显著水平.本试验得出地上部茎秆压碎强度、抗倒指数和地下部根系伤流量、根干质量与倒伏关系最为密切,用其判断大豆植株的综合抗倒伏能力是可行的;大豆群体在轻、中度茎倒伏的情况下,植株具备一定的自我恢复能力。

英文摘要：

【Objective】To solve the problem of lodging with density increase in the soybean production improving process and the soybean lodging-resistance characters in different population structures.【Method】Five levels of planting densities were designed to study the lodging-resistance mechanisms of stem and root selecting the new soybean varieties of Jinong30 and Jinong40 as the tested materials. 【Result and conclusion】Density could change the inner structure of plant population. With the population density increasing,lodging aggravated gradually and the difference was significant compared with the low density. In the high density population structure,the internode length became obviously long compared with the low density; the fresh mass unit stem length of basal internodes was lower than that of upper in-ternodes,and low density was opposite. With the density increasing,the decreasing range of basal stem diameter and fresh mass was more obvious than that of upper internodes. The matter distribution of stem basal from the first to the fifth internodes was changed,which weakened the lodging resistance of the plant. The stem lodging-resistance characters were as follows： with the plant density increasing,the stem crushing strength,stem lodging-resistant index and fresh mass unit stem length decreased significantly;there were significantly negative correlations between all above indexes and lodging; the plant height /stem diameter,height of gravity center,internode length / diameter increased significantly,and there were significant positive correlations. The root nodule number,root dry mass and bleeding amount of soybeans decreased with the density increasing,and there were negative correlations,the correlations between lodging series and bleeding amount and root dry mass reached an extremely significant level with the highest correlation coefficients. The experiment showed that the above-ground stem crushing strength,tem lodging-resistant index,the root bleeding amount and root dry mass most closely correla