| Alfalfa(Medicago sativa L.),a perennial herb of Leguminosae Medicago L.,is the most widely cultivated high-quality forage in China.In the re-growth period of alfalfa,the new sprouts have good edibleness and can be used as a good food for adjusting dietary structure.However,harvesting alfalfa sprouts may have an impact on subsequent hay production,appropriate proportion of harvest is of great significance to ensure the high quality and yield of alfalfa sprouts and hay,and to improve the total income and comprehensive utilization value of alfalfa grassland.In the study,a full-factoral random block design was used,and two factors of alfalfa sprouts harvesting period(early,middle and late stages)and harvest amount(10%,30%and 50%)were set to explore the influence of harvesting different amounts of alfalfa sprouts in each re-growth period on subsequent hay production and total income per unit area of alfalfa grassland in Songnen heavy alkaline-salined region.The results showed that:(1)Among the three re-growth periods,the yield of alfalfa sprouts and subsequent hay were both the highest when harvesting in late stage of re-growth.The sprouts yield was 170.38%and 40.45%higher than that in the early and middle stages,and the hay harvest was 25.64%and 64.54%higher,respectively.(2)With the increase of alfalfa sprout harvest,the average root germination branch number decreased significantly in early stage of re-growth,however,showed a trend of first increasing and then decreasing in middle and late stage of re-growth,harvesting30%alfalfa sprouts with the highest number of branches reaching to 104.5 per square meters and 110.08 per square meters.The average plant height of alfalfa tended to increase with the increase of sprouts harvest in each re-growth period,when 50%alfalfa sprouts were harvested,the average plant height of alfalfa was the highest,reaching to50.58 cm,48.28 cm and 53.40 cm.The total yield of alfalfa hay was the highest when harvesting 30%alfalfa buds in each re-growth period,which was increased by 40.77%and 17.24%(early stage),98.67%and 41.44%(medium stage),26.06%and 14.23%(late stage)compared with 10%and 50%harvest respectively,and the yield was least affected by harvesting sprouts at re-growth period.(3)When 10%alfalfa sprouts were harvested in each re-growth period,the content of crude protein,ether extract,coarse ash of hay was the highest.In addition,the content of calcium,phosphorus,potassium and magnesium in hay was the highest when harvested 10%sprouts,hay had the best quality.When 30%alfalfa sprouts were harvested in each re-growth period,the contents of lignin,neutral detergent fiber,acid detergent fiber of hay was the highest,relative feed value(262.67,158.42,121.55)was the lowest when harvested 10%sprouts,the hay quality was worst.(4)We considered that the sprouts harvested in early stage of re-growth were extremely small,the harvest cost was high,and the edibility of sprouts harvested in late stage was greatly reduced.Using the total income analysis method,considering the total income of harvested sprouts and subsequent hay,it was found that the total income was the highest when harvested 30%sprouts in middle stage of re-growth,reached to 20392yuan/hm~2.At this time,due to the compensatory increased of root germination branches and plant height,the total hay yield reached to 5082 kg/hm~2.The relative feed value of hay was 158.42,which was higher than the first-grade hay quality grade.Therefore,in the grassland with a heavy degree of alkaline-salined in Songnen,harvesting 30%sprouts in middle stage of re-growth could not only avoided the decrease of sprouts quality caused by late harvest,but also ensure higher hay yield in subsequent harvest,and finally improved the total income of alfalfa grassland. |
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