Abstract: To explore the difference in leaf characteristics of alfalfa with different nitrogen efficiency and their effect on yield, this study adopted a field trial and set up four alfalfa cultivars with different nitrogen efficiency (‘LW6010’, ‘Gannong No.3’, ‘Gannong No.7’ and ‘Longdong Alfalfa’) and two nitrogen treatments (0 and 103.5 kg·hm^-2), to compare the leaf characteristics and production performance of alfalfa with different nitrogen efficiency, and used path analysis to explore the influence of leaf characteristics on yield. The results showed that the leaf area, specific leaf weight, leaf number, leaf protein content, vascular bundles, phloem, xylem area, vessel number and total yield of ‘LW6010’ were significantly greater than that of ‘Longdong Alfalfa’ without nitrogen application or with 103.5 kg·hm^-2nitrogen supply. Path analysis showed that the effects of various factors of ‘LW6010’ leaf characteristics on yield were as follows:leaf area > leaf weight > leaf number > leaf increment > specific leaf weight > leaf-stem ratio. In summary, the leaf characteristics of alfalfa are different among different nitrogen-efficiency varieties. Regardless of the level of nitrogen, the comprehensive performance of the nitrogen-efficient alfalfa variety ‘LW6010’ is always better than that of ‘Longdong Alfalfa’. According to the path analysis, among the leaf characteristics of alfalfa, the leaf area and leaf weight are the prominent effectors on production,.

Key words: Alfalfa, Nitrogen efficiency, Leaf characteristics, Production performance, Path analysis

摘要： 为探讨不同氮效率紫花苜蓿（Medicago sativa）叶特征差异及其对产量的影响，本研究采用田间小区试验，设4个不同氮效率紫花苜蓿品种（‘LW6010’、‘甘农3号’、‘甘农7号’和‘陇东苜蓿’）和2个施氮处理（0，103.5 kg·hm^-2），对比研究不同氮效率紫花苜蓿的叶特征及其生产性能，并采用通径分析法探讨叶特征各因子对产量的影响。结果表明，在不施氮和供氮103.5 kg·hm^-2时，‘LW6010’的叶面积、比叶重、叶片数、叶蛋白含量、维管束、韧皮部、木质部面积、导管数量和总产量显著大于‘陇东苜蓿’。通径分析表明，‘LW6010’叶特征各因子对产量的影响依次为：叶面积>叶重>叶片数>叶增量>比叶重>叶茎比。综上，紫花苜蓿的叶特征在不同氮效率品种间存在差异，无论氮水平高低，氮高效紫花苜蓿品种‘LW6010’叶特征综合表现总是优于‘陇东苜蓿’。利用通径分析发现，紫花苜蓿叶特征各因子中叶面积和叶重的产量效应最突出。

关键词: 紫花苜蓿, 氮效率, 叶特征, 生产性能, 通径分析