Comparative Study On Yield And Other Characteristics Of Alfalfa At Different Altitude

Grassland, which is the material basis of developing the local grassland animal husbandry, is one of the most precious natural resource in Tibet。This experiment study on the dynamic changes for characteristics of six alfalfas varieties at different altitude on total yield, reviving yield and height etc. By two successive years'research, I can draw the following conclusions.1.The two successive years'introduction experiment showed that at 2300m altitude, there is not obvious difference on each characteristics among Amerigraze, Affinity, Sitel, Gold Empress, and ZhongMu No. 1 during their growth period except Giant 201, and they can produce seed normally. Furthermore, there is not obvious difference on growth period interval and the total period of growth among these tested items. Comparing with the same varieties in inland, the period of seedling establishment of the tested items are 20 days later, while the growth period are 15 days longer. Therein the extentation of the growth period mainly concentrate on the period between the Budding stage and Fructicative stage. The yield for different cultivars at low altitude listed in descending order as Sitel〉Affinity〉Amerigraze〉ZhongMu No. 1〉Giant 201〉Gold Empress. Speaking of the yield, Amerigraze, Sitel, and Affinity are the alfalfa varieties that adapt to low altitude and have high and stable yield. Giant 201 and Gold Empress have lower yield and less inability of adaptation to the environment, thus it is not suitable to introduce these two to the low altitude area.2.Above 3800m altitude, Amerigraze, Affinity, ZhongMu No. 1 and Sitel didn't grow any more. The whole growth period stop at its growth period, and the yield was lower. At 4500m altitude, they didn't live. Meanwhile, the yield of Giant 201 decreased a lot, which is just about 40% to 50% of that at 2300m altitude. So it is not suitable to mass plant alfalfas at high altitude area in Tibet region expcept for Giant 201.3.At middle and low altitude, there's no big gap on average plant height among Affinity, Sitel, ZhongMu No. 1 and Amerigraze, The decrease degree of plant height was not positive correlations to that of altitude, while with the increase of the altitude, the paces of the decrease of the plant height slow down. The decrease degrees of plant height were different among the verieties and had a certain relationship with the yield. Althought plant height indicated the adaption for zoology, it couldn't be considered as a direct index for forage introduction.