Abstract: To explore the relationship between root characteristics and productivity of alfalfa in early growth stage,in this study,a field experiment was conducted with alfalfa ‘Gannong NO. 7’,‘Gannong NO. 3’,‘LW6010’ and ‘Longdong’ as experiment materials,and two treatments of no nitrogen application and nitrogen application (103.5 kg·hm^-2) were set to study the performance and root characteristics of the 1^st cut alfalfa cut in the planting year and their correlation. The results showed as follows:regardless of nitrogen application,plant height,yield,taproot length,root volume,root surface area,root nodule number per plant,nodule weight per plant,crude protein content and relative feeding value of ‘LW6010’ were the highest,and the plant height,yield,taproot length,root surface area,crude protein content and relative feeding value of ‘LW6010’ were significantly higher than those of ‘Longdong’ alfalfa (P<0.05). The agronomic traits and quality of all varieties were better than that without nitrogen application. According to the correlation analysis,the root characteristics of alfalfa were positively correlated with yield,The root length,root volume,root surface area and nodule weight were positively correlated,and the number of nodule was positively correlated. Therefore,improving the taproot length,root surface area,root volume and nodule characteristics in the early growth stage of alfalfa will improve its yield.

Key words: Alfalfa, Root characteristics, Production performance, The correlation

摘要： 为探究紫花苜蓿生长初期根系特性与其生产性能的关系，以紫花苜蓿品种‘甘农7号’ ‘甘农3号’、‘LW6010’和‘陇东’苜蓿为试验材料，设不施氮和施氮(103.5 kg·hm^-2)2个处理，进行田间小区试验，对种植当年第1茬刈割的紫花苜蓿生产性能和根系特性及其相关性进行研究。结果表明：无论施氮与否，‘LW6010’的株高、产量、主根长、根体积、根表面积、单株根瘤数、单株根瘤重、粗蛋白含量、相对饲用价值最高，其中株高、产量、主根长、根表面积、粗蛋白含量、相对饲用价值显著高于‘陇东’苜蓿(P<0.05)，且和不施氮处理相比均有不同程度的提高，各品种农艺性状和品质均表现为施氮优于不施氮。通过相关性分析可知紫花苜蓿产量与其早期根系特性呈正相关，与主根长、根体积、根表面积及根瘤重呈显著正相关，与根瘤数呈极显著正相关，因此，改善紫花苜蓿生长早期主根长、根表面积、根体积及根瘤特性有助于提高其产量。

关键词: 紫花苜蓿, 根系特性, 生产性能, 相关性