磷水平和接根瘤菌对紫花苜蓿根系形态特征和根瘤固氮特性的影响

Effects of Phosphate Levels and Rhizobium Inoculation on the Root Morphology and Nitrogen-fixing Characteristic of Alfalfa

以‘甘农3号'紫花苜蓿(Medicago sativa‘Gannong No.3')为材料,采用营养液沙培法,研究了磷及根瘤菌对紫花苜蓿根系形态和根瘤固氮酶活性的影响,结果表明:接种根瘤菌或在一定范围内(0~2000μmol·L^(-1))提高磷水平,均可显著增加紫花苜蓿的根长、根表面积、根平均直径、根体积和根系活力,并使其根瘤数增多,根瘤重增大,固氮酶活性显著增强,植株全氮含量增加;与不接菌相比,接菌提高了紫花苜蓿对磷的需求;本试验条件下紫花苜蓿所需磷素最佳范围为1000~1500/μmol·L^(-1)。

The effects of phosphate levels and rhizobium on the root morphology and nitrogen-fixing characteristic of Medicago sativa ＇ Gannong No.3＇ were studied by sand culture method.The results showed that rhizobium inoculation and appropriately improving the phosphorus levels（0～2000μmol·L～（-1）） could markedly increase alfalfa root length,root surface area,average root diameter,root volume,root nodule number and root nodule weight,as well as root activities,nitrogenase activity and total nitrogen content;Rhizobium inoculation increased the demands of alfalfa for phosphate;The optimal phosphorus level of alfalfa is from 1000μmol·L～（-1） to 1500μmol·L～（-1）.