The Response Of Medicago Falcata L. To Mowing Intensity

Medicago falcata L. originated from Siberian area, it mostly distributed in cold areas of Xinjiang,northern Inner Mongolia and the north part of Northeast. Medicago falcata L. is rich in nutrition and tolerant to drought, cold, salt and alkali, and has good palatability. It takes an important role on resolving the problem that lack of protein in feed, as well as the soil fertility degradation problem. By taking Medicago falcata L. CV. Ximeng as the research object, analyzed the correlation between different stubble height and leaf area,branch number,photosynthesis,transpiration,energy accumulation of Medicago falcata L.,and revealed responding mechanism of mowing intensity in Medicago falcata L. provide scientific basis for rational utilization of artificial grassland and stable development of grassland animal husbandry.Getting the following preliminary conclusions:1.With the stubble height increased,the height,leaf area,branch number,internodes and internodes length of Medicago falcata L. had a tendency of decreasing. However, the number of secondary root decreased initially and then increased. When the stubble height was Ocm it had a promoting effect to the growth of Medicago falcata L.2.The diurnal changes in the photosynthetic rate of the control and the Medicago falcata L. whose stubble height was 8cm showed single peak curves, all the others showed double-peak curves, and the daily mean photosynthetic rate of the Medicago falcata L. which have different stubble heights were higher than the controls. However, the diurnal changes in the transpiration rate of the Medicago falcata L. all showed single peak curves, with the stubble height increased,the transpiration rate of Medicago falcata L. had a tendency of increasing. When the stubble height was Ocm, the Medicago falcata L. not only resisted losing water in a lower transpiration rate but also it had a higher water use efficiency. The photosynthetic active radiation (PAR) was the most important environmental factor which influenced the photosynthetic rate (Pn) and the transpiration rate (Tr) of the Medicago falcata L. which had different stubble heights.3.When the stubble height is 0cm, the aboveground biomass of the Medicago falcata L. showed a equal-compensation. The belowground biomass and stem/leaf ratio of that were much lower than the control (P<0.05),and the total biomass and the root/shoot ratio of the Medicago falcata L. which had different stubble heights were as follows:CK>0cm>5cm>8cm>3cm and 3cm>5cm>8cm>CK>0cm. The height and the branch number were the major factors which influenced the aboveground biomass of the Medicago falcata L.4.The stubble height had no distinct influence on the content of organic matter of soil in the rhizosphere of the Medicago falcata L.. Comparing with the control, the total N in surface layer of 0-10cm of the Medicago falcata L. whose stubble height were 0cm,3cm,5cm and 8cm, decreased 35.4%,24.8%,32.7%,37.2% separately. However, the total P in surface layer of 20-30cm of the Medicago falcata L. whose stubble height was 3cm was much lower than the control(P<0.05).5.The best stubble height was Ocm for the annual or biennial Medicago falcata L.