Effect of Mowing Frequency on Yield Competition and Leaf Function of Mix-sowing Grassland of Bromus inermis and Alfalfa

Two-year grass Caoyuan NO.3 alfalfa and bromus inermis were used as the experiment materials,and two pasturages were treated to mow.By analyzing yield and net photosynthetic rate of head stubble of the next year,the results showed that the competition of bromus inermis decreased and yield reduced with pushing the first mowing time.Reducing the year mowing frequency could increase the competition of bromus inermis,but restrain the competition of alfalfa.The net photosynthetic rate,leaf stomata conductance and transpiration rate of head stubble alfalfa gradually reduced after mowing in the next year,with last year mowing frequency increased,and net photosynthetic rate,leaf stomata conductance and transpiration rate of bromus inermis gradually increased with increasing mowing frequency.The results showed that next-year alfalfa had competition advantage with low mowing frequency in growth course,and next-year bromus inermis had competition advantage with high mowing frequency in growth course.