为从茎秆强度的角度研究套作大豆苗期对荫蔽胁迫的响应及耐荫抗倒机制,采用耐荫性不同的3个大豆材料,在玉米大豆套作和单作两种种植模式下,对茎秆的纤维素、可溶性糖、蔗糖、淀粉含量及蔗糖代谢中关键酶活性以及茎秆抗折力、抗倒伏指数等进行测定,研究它们与套作大豆苗期倒伏的关系.套作大豆苗期倒伏严重,茎秆抗折力、抗倒伏指数、纤维素、可溶性糖、蔗糖、淀粉含量和相关酶活性均显著低于单作.不同大豆材料受套作荫蔽影响程度不同,强耐荫性大豆南豆12茎秆抗折力降低幅度最小,在套作环境下其茎秆抗折力、抗倒伏指数大,纤维素、可溶性糖、蔗糖、淀粉含量高,酶活性强.相关分析表明:套作大豆苗期茎秆糖含量均与抗折力呈极显著正相关,与倒伏率呈极显著负相关;蔗糖含量与蔗糖磷酸合酶(SPS)、蔗糖合酶(SS)、中性转化酶(NI)活性呈极显著正相关,与酸性转化酶(AI)活性相关性不显著;纤维素含量与SPS、SS呈极显著正相关,与NI呈显著正相关,与AI相关性不显著.套作环境下,强耐荫性大豆苗期茎秆中较高的SPS、SS活性是其维持高蔗糖和纤维素含量的酶学基础,而高纤维素含量有利于提高茎秆强度,进而增强其抗倒伏能力.本研究应用玉米大豆套作种植系统,从苗期抗倒角度,探明了光环境对不同基因型大豆茎秆纤维素代谢的影响机制,为下一步筛选耐荫抗倒大豆品种提供了理论依据. In order to study the response of shading soybean seedlings to shading stress and shading tolerance mechanism from the perspective of stalk strength, three soybean materials with different shading tolerances were used. The content of cellulose, soluble sugar, sucrose and starch, the key enzyme activity in sucrose metabolism and the stress resistance and lodging resistance index of stems were measured to study their relationship with the intercropping soybean seedling lodging. The seedling lodging was serious, the anti-fracture ability, lodging resistance index, cellulose, soluble sugar, sucrose, starch content and related enzyme activities of the stems were significantly lower than those of the single crops.So different soybean materials were affected by the shade, Soybean Soybean 12 had the lowest decrease in the bending strength of its stems, and its stems had high anti-collapse and lodging resistance index, high cellulose, soluble sugar, sucrose and starch content and strong enzyme activity under the environment of intercropping. The contents of sucrose and sucrose phosphate synthase (SPS), sucrose synthase (SS), neutrality Invertase (NI) activity was extremely significantly positive (P <0.05), but not with the activity of acid invertase (AI). The content of cellulose was significantly and positively correlated with SPS and SS, but positively correlated with NI, but not with AI The high SPS and SS activity of Soybean in seedling stage was the basis of its enzymatic activity to maintain the content of high sucrose and cellulose, while the high cellulose content was beneficial to improve the stalk strength and thus its lodging resistance.In this study, Maize and soybean intercropping systems were used to study the mechanism of light environment on the cellulose metabolism of different genotypes of soybean stalks from the anti-chamfer angle at seedling stage, which provided the theoretical basis for the next screening of tolerant and anti-resisting soybean varieties.