Effects Of Waterlogging Stress On Growth And Physiological-Biochemical Changes On Different Alfalfa Varieties

The areas along the Yangtze River are the important production base for pasture of Anhui province.However,the areas have high amount of precipitation in summer rainy season,so the alfalfa's productivity is lower or even death duo to the lack of waterlogging resistance ability.Filtering the pasture with stronger waterlogging resistance ability is conducive to the cultivation and utilization of alfalfa in these areas.In addition,it has great significance on the development of animal husbandry.In this paper,five alfalfa varieties,including Jinjuanghou(Jh),Aerjinggang(Ar),Weiduoliya(Wd),Juneng 551(J551) and Junengnaishi(Jn),are as the experimental objects for flooding experiment.The results showed that:1.The influence of waterlogging stress on growth and development of different alfalfa varietiesThe influence of flooding stress on the growth of five alfalfa varieties were different.Flooding stress had tiny effect on plant branch number and internode number of the five alfalfa varieties.The height,leaf number,length of root and dry weight of root are decline during the whole experiment,but there are increasing trends before the flooding treatment.The sequence of falling range of leaf number from low to high is that: Jh < J551 < Jn < Wd<Ar.The length of root of five alfalfa have no obvious change,the falling range of dry weight of Wd and Ar is higher than others.After flooding treatment,the growth rates of alfalfa raised at first,then decreased.The ability of damp tolerant of JH,J551 and JN has no significant difference,but that is much stronger than that of Wd and Ar.The high of Jh is the highest,while the height of others is no markedly difference.2.The influence of waterlogging stress on photosynthetic capacity of different alfalfa varietiesThe transpiration rates and photosynthetic capacity of 5 alfalfa varieties under water stress declined continuously,and the rate of transpiration decreased significantly higher than photosynthetic rate.In the early stage of the water stress,the photosynthetic rate of AR is relatively high.It decreased rapidly at the 2th day.In the stress cycle,the photosynthetic rate of Ar and Wd decreased significantly larger,and at the end of the stress,the photosynthetic rate of this two varieties was the lowest.The photosynthetic rates of 5 varieties from low to high were that: Wd < Ar < Jh < J551 < Jn.The tendency of the transpiration rate was consistent with photosynthetic rate.3.The influence of waterlogging stress on enzymatic activity of different alfalfa varietiesUnder water stress,the POD?SOD and CAT activity of 5 alfalfa varieties raised at first,then decreased,and the degree of change varied with varieties.At the end of the stress,the POD activity of 5 varieties from high to low were that: Jn <Jh< J551 < Wd < Ar.The SOD activity showed that: Jn <J551< Jh < Ar < Wd.The CAT activity are consistent with SOD.The activity of Ar and Wd had no obvious difference.At the end of the stress,the activity of Ar and Wd were almost unanimously.In the stress cycle,the content of MDA raised continuously.The biggest dropped in Ar and Wd,while Jh comes second,and the minimum dropped in J551 and Jn.At the end of the stress,the both reached extremely significant difference with other varieties.4.The influence of waterlogging stress on enzymes of different alfalfa varietiesIn the early stage of the water stress,the LDH ? ADH and PDC activity of 5 alfalfa varieties raised obviously and decreased after the peak value.At the 5th day the LDH activity of Ar and Wd was apparently higher than Jh.Jn and J551 was relatively the lowest,reaching extremely significant difference with other varieties.Under these conditions,the ADH activity of Ar and Wd was apparently higher than that of Jh.Jn and J551 was relatively the lowest,reaching extremely significant difference with other varieties.The PDC activity of Jn and J551 was apparently lower than other varieties.5.The influence of waterlogging stress on yield of different alfalfa varietiesIn the stress cycle,the yield of Jh and Ar declined continuously.The others showed a small increase at the 1th day,and then declined continuously.The biggest dropped in Ar and Wd.At the end of the stress,those dropped 57.40% and 38.38% respectively than control.Jh comes second.The yield of J551 and Jn dropped the minimum,dropping 19.860% and 13.11%respectively than control at the end of the stress.Because the yield of Jh under the control condition was significantly higher than the others,it has no significant difference with J551.6.The influence of waterlogging stress on quality of different alfalfa varietiesUnder waterlogging stress,the crude protein content of 5 alfalfa varieties raised at first,then decreased.The detergent fiber content changed in the opposite.Under the control condition,the crude protein content of Jh?J551 and Jn was higher than 18.Those were still significantly higher than other two varieties at the end of the stress.on this condition,the neutral detergent fiber content of Jh ? J551 and Jn had no significant difference,butsignificantly lower than the Ar and Wd.The change of acid detergent fiber content was similar.7.The influence of waterlogging stress on yield of different alfalfa varieties on next seasonIn the stress cycle,the yield of different alfalfa varieties on next season declined continuously.The yield of Jh dropped the minimum,while J551 and Jn comes second.The biggest dropped in Ar and Wd.The yield of Jh on next season at the 5th day reached 4297.84kg/acre,had extremely significant difference with other varieties.Jn comes second,reaching extremely significant difference with other 3 varieties.