The Impact Of Different Mowing Date On The Seed Yield And Forage Production Of Medicago Sativa L. In Western Jilin Province

Alfalfa (Medicago sativa L.) is an important leguminous plant which is widely cultivated in the world. Northeast China is one of the advantages of alfalfa producing region. However, the low seed yield of alfalfa restrict the large area cultivation in northern China.The alfalfa seed yield is strongly lead to climate, temperature and other ecological factors, in especial, the main reason why seed yield has significant difference is the alfalfa florescence precipitation. Therefore, this research investigates the influences of different mowing time on alfalfa growing period, flowering dynamic change, seed yield, seed quality, forage yield based on the precipitation of different month in Changling County, the west of Jilin Province. We take the Zhaodong alfalfa which is wildly cultivated in the northeast China as the study subject. It is our goal to seek the effective way to alfalfa seed yield increase. The result of this research has important practical value for guiding seed production in northeast China. The results showed that:(1) In west of Jilin Province, when precipitation is≤2.0mm/d, the time of assurance rate less than80%was late June and July. In late August, September and October, the assurance rate was above80%.(2) The single flowers of alfalfa bloom at about8:00, and the peak blooming is just between13:00-16:00. At the full flowering stage, the peak of wilt and podding appears at night. The single flowers of Medicago sativa L. at the early and full flowering stage almost stop blooming at about18:00.(3) The different mowing treatment have an enormous affect on the forage yield. With the alfalfa growing, the yield is on the increase until full flowering stage to the climax. In the production practice, the mowing time should not be earlier than the early flowering stage only taking forage yield into consideration.(4) The different mowing treatment have an enormous affect on the forage nutrition. With the alfalfa growing, the content of CP is falling, however, the content of ADF and NDF is increasing. At early growing stage, the content of alfalfa nutrition changes at a slower speed. At late growing stage, especially the full flowering stage, the content of nutrition changes dramatically.Consequently, the mowing time should not be later than early flowering stage in order to get the high quality alfalfa.(5) The different mowing treatment have an enormous affect on the seed yield. The seed yield is increased significantly after mowed compared to the control group. In our experiment, we adjust the florescence to mid-August. The result showed that the seed yield of treatment group had significantly exceeded the yield of control groups (P<0.01). Therefore, the adjusting of florescence by mowed improves the yield of alfalfa seed production in western Jilin Province.(6) The different harvest time has great impact on alfalfa seed germination and seeding growth in the same mowed treatment. In order to gain high-quality seed, we should harvest in10-15days after milky ripe stage in the un-mowed group. While, in the mowed group,we consider5-10days after milky ripe stage as the appropriate harvest time.(7) The different mowing treatment is also an influence in alfalfa seed germination and seeding growth. The mowing treatment of June10has significantly improved the seed germination rate and seedling growth rate (P<0.01).