Abstract:

In order to illustrate the dynamic change of the production performance of alfalfa between cutting times and years, two experiments for seven years (22 varieties) and four years (14 varieties) were conducted in the Hai River Plain. The results indicated that the average dry matter yields decreased with the cutting times increasing; the dynamic of dry matter yields for 4 times one year was:1^st cutting > 2^nd and 3^rd cutting > 4^th cutting, the dynamic of dry matter yields for 5 times one year was:1^st cutting > 2^nd cutting > 4^th cutting > 3^rd cutting > 5^th cutting. The average dry matter yields of the 1^st and 2^nd cutting accounted for over 52% of the whole year, and the yields of 3^rd cutting could only account for less than 25%. The average plant height (both 22 varieties and 14 varieties) declined with the cutting times increasing. The average Leaf-Stem ratio (both 22 and 14 varieties) of the 2^nd cutting was significantly higher than the 3^rd and 4^th cutting (P<0.01), the 4^th cutting was the lowest. The average crude protein content (both 22 and 14 varieties) of the 2^nd and 3^rd cutting were higher than the 3^rd and 4^th cutting, and the differences were significant (P<0.01). There were obviously "summer slump" phenomena which could cause the waste of light, temperature and water resources. The seven years continuous test showed that the yields decreased from the fifth years, therefore the suitable utilized years were 4~5 year in the Hai River Plain.

Key words: Alfalfa, Production performance, Different cutting times, Interannual, Dynamic change

摘要：

在海河平原区，先后选取22个、14个苜蓿（Medicago Stiva）品种，雨养条件下通过7年和4年的试验结果表明：不同茬次干草产量表现为逐渐降低的趋势，每年刈割4次：第1茬 > 第2、3茬 > 第4茬；刈割5次：第1茬 > 第2茬 > 第4茬 > 第3茬 > 第5茬；前2茬苜蓿年平均干草产量均占全年总产量的52%以上，第3茬干草占全年总产量的25%以下；随茬次的增加，株高总体上表现为逐渐下降的趋势；第2茬草的叶茎比极显著高于第3、4茬（P<0.01），第4茬草的叶茎比最低；粗蛋白含量为第2、3茬>第1、4茬，并且差异极显著（P<0.01）。苜蓿在海河平原区存在明显的“夏眠”现象，造成了光、温、水资源的浪费。7年连续测定结果表明，在海河平原区紫花苜蓿适宜的利用年限为4~5年。

关键词: 紫花苜蓿, 生产性能, 不同茬次, 年际间, 动态变化