中文摘要：

2006—2008年调查了12个国外引进苜蓿品种头茬单株干重与产量性状间的关系。结果表明,主、侧枝数及主、侧枝节间数是构成苜蓿单株产量性状的第1主成分,占总方差的58.05%,其中侧枝数（r=0.689）、侧枝节间数（r=0.526）与单株干重显著相关（P〈0.05）,可作为苜蓿高产品种选育主要目标性状;苜蓿株高与单株干重不相关,与主枝数（r=-0.650）、主枝节间数（r=-0.637）显著负相关（P〈0.05）,栽培管理中适当限制植株高度有利于产草量的提高;依单株干重聚类的Ⅰ类苜蓿（Pondus、WL-414）头茬年均侧枝数显著高于其他两类苜蓿,年均侧枝节间数与Ⅱ类差异不显著,但显著高于Ⅲ类（P〈0.05）。Ⅰ类苜蓿年均叶茎比分别比Ⅱ类、Ⅲ类提高了6.05%和10.91%,且与Ⅲ类苜蓿差异显著（P〈0.05）,是具高产优质的种质资源。

英文摘要：

Yield of alfalfa （Medicago sativa L.） is closely related to its plant characteristics and the yield in 1st cutting contributes the majority to the annual harvest with the dry matter per plant （DMPP） determining the total community yield. The relationship between dry matter per plant in 1st cutting and yield-related traits （plant height, branch characteristics and leaf to stem ratio） of 12 introduced alfalfa varieties were studied in three continuous years （the 3–5 growth years） under field condition. There was a significant positive correlation between dry matter per plant and sub-branch number （SBN） （r = 0.689）, and between DMPP and internode number of sub-branch （SBIN） （r = 0.526）. The 1stprincipal component was composed of the branch number （BN）, SBN, branch internode number （BIN） and SBIN, which accounted for 58.05 percent of total variance. This suggests that SBN and SBIN may be considered as the main objective characteristics for alfalfa breeding selection. The plant height （PH） had no significant correlation with DMPP, but a significant negative correlation with BN and BIN （r = –0.650 and –0.637, respectively）, indicating that the control of the plant height of alfalfa by filed management appropriately is beneficial to the yield. The cluster analysis for DMPP showed that the 3-year average SBN in 1st cutting for group 1 varieties （the group with the highest DMPP including Pondus and WL-414） was significantly higher than other two groups. The SBIN had no significant difference between group 1 and group 2, but showed significant difference between group 1 and group 3 （P〈0.05）. The leaf to stem ratio （LSR） of group 1 was 6.05% higher than that of group 2 and 10.91% higher than that of group 3, and the difference was significant between group 1 and group 3 （P〈0.05）. Among the varieties, Pondus and WL-414 had higher breeding value in yield and palatability than other varieties.