铝胁迫下大豆根系分泌物对根际土壤的影响

以2个大豆品种（浙春2号和浙春3号）为材料，设置了4个铝浓度，分别在铝处理7d和14d时，测定大豆根系分泌物中的氨基酸、有机酸及可溶性糖，同时对大豆根际土壤的pH值、土壤酶和土壤呼吸速率进行分析。实验结果显示，虽然根系分泌物对根际土壤具有一定的酸化作用，但是随着铝浓度的升高，根系分泌物有使根际土壤酸碱度趋向平衡的效应。低铝浓度下，大豆根系分泌较多的可溶性糖和氨基酸，促使根际土壤酶活性的增强和土壤呼吸速率的提高，同时还可分泌较多的柠檬酸，与大豆的耐铝性相关。高铝浓度抑制主要根系分泌物的分泌，降低土壤酶活性和土壤呼吸速率；但高铝胁迫增加可溶性糖分泌量。实验结果表明，浙春2号大豆比浙春3号大豆耐铝；随着铝处理时间的延长，铝毒害作用明显。

Root exudates of soybean(Glycine max)under aluminium stress and their effect on rhizosphere soils

The potential effects of soybean(Zhechun No.3 and Zhechun No.2) root exudation on rhizosphere soils were studied with soil cultivation and four different concentration of aluminium(Al3 ) were designed.Amino acids,organic acids and soluble sugars,as well as pH,respiration rate and enzymes in soybean rhizosphere and bulk soils(control) were mensurated after treated for 7 days and 14 days respectively.The results indicated that root exudates had a function of soil acidification.Under low concentration of Al3 ,more amino acids and soluble sugars were exudated from Al3 -stressed soybean roots,promoting the activities of soil enzymes and the respiration rate of rhizosphere soil,and more organic acids were exudated.High concentration of Al3 restrained the main root exudates,decreasing the activities of soil enzymes and the respiration rate of rhizosphere soil in some degree,but increasing the soluble sugars.It was also showed that Zhechun No.2 had stronger ability of Al-tolerance.With prolonging of Al3 treatment time,the poison effect of aluminium to soybean was more remarkable.