中文摘要：

为探究具有高固氮酶活性的变栖克雷伯氏菌DX120E回接甘蔗后的固氮能力和促生效应,以甘蔗品种B8和GT21的无菌组培苗为材料,采用根部接种的方法,研究固氮菌DX120E在甘蔗体内的定殖数量及其对甘蔗组培苗植株生长、氮代谢关键酶活性和硝态氮含量及矿质元素吸收的影响.结果表明：固氮菌DX120E能在甘蔗根和地上部分组织内生存和定殖;接种固氮菌DX120E可以有效促进甘蔗植株生长和对矿质营养的吸收;显著提高甘蔗植株体内的硝酸还原酶（NR）活性,同时也能在一定程度上提高植株体内谷氨酰胺合成酶（GS）活性,增加硝态氮含量.表明变栖克雷伯氏菌DX120E对甘蔗具有明显的促生效应,在生物固氮肥开发方面具有较大的应用前景.

英文摘要：

In order to investigate the growth promoting effect of inoculating Klebsiella variicola DX120E, a bacterial strain with high activity of associative nitrogen fixation, on sugarcane, the strain was inoculated through roots into the pathogen free micropropagated seedlings of two sugar- cane cultivars B8 and GT21. The bacterial numbers colonized in sugarcane plants, the activities of the key enzymes for nitrogen metabolism, the nitrate concentration and nutrient uptake were ana- lyzed. The results indicated that the DX120E strain could live, propagate and colonize in the roots and aerial parts of sugarcane seedlings. The DX120E inoculation could effectively promote the plant growth and nutrient uptake, significantly improve the nitrate reductase （NR） activities, and in- crease the glutamine synthetase （GS） activities and nitrate concentration in certain degree in the leaves, compared with the uninoculated seedlings. It was suggested that Klebsiella variicola DX120E possesses a significant growth promoting effect on sugarcane plants which has a great appli- cation potential in developing biological nitrogen fixation fertilizer for sugarcane.