摘要：

为研究不同氮素水平下接种大豆根瘤菌对大豆生长和结瘤固氮的影响,以大豆品种Williams 82为试验材料,采用蛭石法种植,设置无氮、低氮和高氮3种浓度的硝酸盐处理,接种USDA110大豆根瘤菌,研究不同氮素水平对大豆结瘤及氮含量的影响。结果表明,不同施氮水平对根瘤数目、根瘤干质量和根干质量都有不同程度的影响,施加高氮营养液会抑制大豆结瘤,而无氮处理则促进了大豆结瘤;根干质量呈现相反的变化趋势,无氮处理的根干质量最小,高氮处理的根干质量最大。不同施氮水平下,大豆不同器官氮含量在接菌和不接菌间表现出不同的变化趋势;高氮处理下的氮素含量显著高于低氮、无氮处理,不同器官氮含量整体表现出叶>根>茎的现象;不同氮水平条件下,不同叶位叶绿素值(SPAD值)在接菌与不接菌间无明显差异。叶形态指标的测定结果显示,高氮处理下叶面积、叶周长、叶长和叶宽均显著高于无氮处理;无氮接菌后叶面积和叶周长显著大于无氮不接菌处理,表明接菌不仅促进了根生长,还刺激了叶片增大。由此可知,不同氮素水平下,接种根瘤菌对大豆幼苗的结瘤固氮和生长发育的变化规律不同,适当增施氮素营养、配合根瘤菌剂的使用可促进大豆生长发育及氮素利用吸收。

关键词: 大豆, 氮水平, 固氮结瘤, 氮素积累, 生长

Abstract:

To study the effect of soybean rhizobia inoculation under different nitrogen levels on soybean growth and nodulation and nitrogen fixation,soybean Williams 82 was used as the test material to be planted by vermiculite method,and nitrate treatments with three concentrations of no nitrogen,low nitrogen and high nitrogen were set up.Inoculate USDA110 soybean rhizobia to study the effect of different nitrogen levels on soybean nodulation and nitrogen content.The results showed that different levels of nitrogen application had different effects on the number of nodules,nodule dry weight and root dry weight.The application of high-nitrogen nutrient solution could inhibit soybean nodulation,while no nitrogen treatment promoted soybean nodulation.At the same time,the root dry weight showed the opposite trend,the root dry mass of the no nitrogen treatment was the smallest,and the root dry mass of the high-nitrogen treatment was the largest.Under different nitrogen levels,the nitrogen content of different organs of soybean showed different changing trends between inoculation and non-inoculation.Under different nitrogen levels,the nitrogen content under high nitrogen treatment was higher than low nitrogen and no nitrogen treatment,and the nitrogen content of different organs showed the phenomenon of leaf>root>stem overall.Under different nitrogen levels,the chlorophyll values(SPAD)of different leaf positions showed that there was no significant difference between inoculation and non-inoculation.The measurement results of leaf morphological indicators showed that the leaf area,leaf circumference,leaf length and leaf width of high nitrogen treatment were significantly higher than low nitrogen and no nitrogen treatments.Leaf area and leaf circumference after nitrogen-free inoculation were significantly greater than those without nitrogen-free inoculation,indicating that inoculation not only promoted root growth,but also stimulated leaf enlargement.It can be seen that rhizobium inoculation had different changes for nodulation,nitrogen fixation and growth and development of soybean seedlings under different nitrogen levels.Appropriate increase in nitrogen nutrition combined with the use of rhizobia was an effective way to promote the growth and development of soybean and the utilization and absorption of nitrogen.

Key words: Soybean, Nitrogen level, Nodulation and nitrogen fixation, Nitrogen Accumulation, Growth