| This paper was a partial content of '948' project of agricultural Department about introduction and breeding the new alfalfa varieties with high yield and fine quality and high resistance. The botanical character, economic character, biological character of diverse varieties were analyzed to evaluate their productive force and adaptation in order to select excellent alfalfa varieties with high yield and good adaptation for exploiting dry land agriculture, expanding introduced alfalfa varieties, integrating farming?livestock, improving grassland, constructing grass-industry field and exploit ting barren land.1. Thirty-one alfalfa varieties had obvious different botanical character. Bei Jiang alfalfa had good productive characters, such as large- diameter stem, high weight per stem, long internodes, large leaves areas, good power of productive stem, more leaves and root diameter. It had a few lateral roots and deeply root systems. Zhonglan alfalfa had analogous characters to Bei Jiang. It has good power of resisting water stress with deeply taproot and more lateral root. Ameristand201+z had good complex character and superiority In relative herbage yield potential, so were Ameristand401+z , Avalanche+z> Arriba, Affinity+z, 13Rsuperme> Aggressor. Application of gray system theory to evaluate productive power of thirty-one alfalfa varieties, Beijiang alfalfa had obtained the highest score. Avalanche+z, Ameristand201+z, Amerigraze401+z were secondary.2. Weight per stem , numbers of branches per stem, length per branch , weight per branch of diverse alfalfa varieties continued to increase with growth progress. Especially, length per branch, weight per branch increased quickly. 13R supreme and German large leave grew earlier in spring and their yield component factors were higher than other varieties. Beijiang and Zhonglan alfalfa adapted to local climate with high vigor and accumulated a lot of dry matter in every stage. Ameristand201+z and Amerigraze401+z grew late in early spring. With temperature ascending, they began to grow fast and accelerated dry matter accumulation to obtain high yield.3. There was obvious difference in economic characters of diverse alfalfa varieties. Beijiang alfalfa and Zhonglan alfalfa had good growth power, quick growth speed, high photosynthesis rate. Their low leaf-to-stem weight ratio and dry matter-to-fresh biomass weight ratio affected forage yield and quality.-Ill-13R superme and German large leave grew earlier in spring and had good growth vigor. They had Low power to produce branch that was a limit factor to improve forage yield. Ameristand201+z and Amerigraze401+z et had quick growth speed and high accumulation power, high photosynthesis rate, high leaf-to-stem weight ratio. They had superiority in relative yield potential than others. Application of cluster analysis to evaluate productive force of thirty-one alfalfa varieties showed that they were divided into four grades.4. The diverse alfalfa varieties had obvious difference on stem structure. Amerigraze401+z and Beijiang alfalfa et had strong power of producing branch and good stem structure. They have a superior basis of obtaining high yield . Vertical biomass structure on above ground was divided into four grades. The highest Biomass of the diverse alfalfa varieties concentrates on the height of biomass layer 20~60cm and slowly descended forward two end respectively. The height of biomass layer of Alfagrazc and Archer lay in 100?20cm.Their biomass structure patter displayed high weight on median layer and low weight on two ends. The maximum biomass layer weight of ISRsuperme and Abilene lay in 0?20cm. Its' biomass structure was "pyramid' pattern. The common character of biomass structure within underground slowly descended with the depth of soil layer. Biomass of diverse alfalfa varieties and different soil layer lay in obvious difference.4. Resistance to diverse alfalfa varieties had obvious difference. Beijiang and Zhonglan alfalfa hade high resistance to peronospora aestivalis. Zhongmu and Baofeng...
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