A Study On Eco-physiological Characteristics Of Alfalfa Under Low Phosphorus Stress

Phosphorus plays an important role in the process of plant growth.But the available phosphorus content cannot meet the growth of plants in most of the cultivated land in China.Alfalfa growth needs a large of number phosphorus.In the development of animal husbandry industry,alfalfa is important forage resource.At present,the shortage of phosphorus affect animal husbandry development.In order to explore the resistance to low phosphorus among different alfalfa(Medicago sativa L.)varieties,we selected the 10 alfalfa varieties from China and other countries.Alfalfa seedlings were adopted by solution culture method.Treat a normal phosphorus(500 ?mol·L-1 KH2PO4)as the control group and a low phosphorus(5 ?mol·L-1 KH2PO4)as treatment group.With 20 d of low phosphorus treatment,we detected the morphological indexes,Phosphorus content?Phosphorus using efficiency and ACP activity.By using principal component analysis and membership function analysis of the different varieties of low phosphorus tolerance ability.The main results are as follows:(1)Different indexes was of significant differences among various varieties in low phosphorus environment after 20 days.And low phosphorus limited the growth of alfalfa.Compared with the control group,plant height decrease(Coefficient of resistance to low phosphorus(0.6848 ~ 1.0219),dry shoot weight decreased(Coefficient of resistance to low phosphorus 0.4098~1.2781),dry root weight increased(Coefficient of resistance to low phosphorus 0.4274~1.5954),Root/shoot ratio increased(Coefficient of resistance to low phosphorus 0.9325~1.6983),root length increased(Coefficient of resistance to low phosphorus 0.60~1.10),Root surface area increased(Coefficient of resistance to low phosphorus 0.58~1.22),phosphorus content decreased Coefficient of resistance to low phosphorus 0.40 ~ 0.66),phosphorus utilization increased(Coefficient of resistance to low phosphorus 1.51~2.50),ACP activity increased(Coefficient of resistance to low phosphorus 0.7423 ~ 1.4969).By using principal component analysis and membership function analysis,Sort of low phosphorus tolerance as strong and weak.AoHan is the strongest among 10 varieties of alfalfa.Victoria is the weakest.(2)Compared with adaptation strategies,more resistance to low phosphorus species and low phosphorus species are different.The experimental results show: AoHan fell less than Victoria in steam height,dry shoot weight,phosphorus concentration,transpiration rate,photosynthetic rate,stomatal conductance under low phosphorus.The growth of AoHan more than Victoria in total root length,root surface area,dry root weight,ACPA under low phosphorus.We thought that Victoria is more sensitive to phosphorus.And AoHan more resistance to low phosphorus.