Research And Comprehensive Evaluation On The Stress Resistance Of Six Gramineous Forages In Qinghai Province

Qinghai Province is located in the northeast of the Qinghai-Tibet Plateau.Its unique climatic characteristics determine the natural grassland that has been mainly distributed in alpine meadows.However,due to climate change and human activities in recent years,natural meadows have been extensively degraded,which has seriously affected the development of local animal husbandry and ecological balance.Therefore,it is imminent to study and select excellent forages that are suitable for local growth.This experiment was conducted on six kinds of alpine forage grass: Roegneria kokonorica,Alopecurusa equalis,Roegneria grandiglumis,Bromus inermis,Agropyron cristatum and Elymus breviaristatus cv.Tongde were treated under drought stress,salt and cold resistance,respectively,and measured under different stress treatments.The indicators of the physiological and biochemical mechanism of the anti-stress system were systematically described: Systemic analysis of the drought-tolerance,salt-coldity of the six grasses tested were performed using the membership function method and the cluster analysis method,respectively.The results are as follows:1.The effects of drought stress on seed germination and seedling stage physiological indexes were studied by PEG simulation of water stress and continuous drought,and the drought resistance of six gramineous grasses was evaluated comprehensively.The main conclusions of this study are as follows: The drought resistance of seed germination period showed that low PEG concentration(5%)promoted seed germination,and high PEG concentration(10% ~ 15%)significantly inhibited seed germination rate.The seedling of the seedlings treated by successive drought,and the relative water content,malondialdehyde content,soluble sugar content and chlorophyll content of the physiological indexes were measured.Two periods of membership value comprehensive analysis,the drought resistance of six kinds of pasture was obtained:Alopecurusaequalis>Bromusnermis>Elymusbreviaristatuscv.Tongde>Roegneria kokonorica>Roegneriagrandiglumis>Agropyroncristatum.2..The chlorophyll content,malondialdehyde(MDA)content,soluble sugar content and free proline(PRO)content in the germination stage and seedling stage were determined by different concentrations of NaCl solution.The results show that with the increase of NaCl concentration,proline content of six kinds of grass blades also will increase,the MDA content in the overall upward trend,chlorophyll andsoluble sugar content was lowered after the first change,Using a membership function to evaluate the antisalinity of six varieties of grasses and seedlings during the germination and seedling period: The salinity tolerance of six grasses is from large to small : Roegneria grandiglumis>Alopecurus aequalis>Bromusinermis>Elymusbreviaristatuscv.Tongde>Agropyron cristatum>Roegneria kokonorica.Tongde.3.Measuring the grass seed germination rate under different temperature treatment,the seedling stage herbage in artificial calibrate control in the low temperature cold resistance exercise,freezing process and thawing recovery growth,analysis to determine the phase six kinds of forage grass of MDA,soluble sugar and proline content.The results showed that the content of MDA increased significantly after cold resistance training,the contents of soluble sugar and proline increased after cold resistance training and freezing treatment,and decreased after returning to green.The membership function method was used to evaluate the cold resistance,the order of the coldness is: Bromus inermis>Alopecurus aequalis>Roegneria kokonorica>Elymus breviaristatuscv.Tongde>Agropyron cristatum>Roegneria grandiglumis.4.Results of a cluster analysis on three indicators of stress resistance revealed that in these six Forage grass species,Alopecurusa equalis had the strongest stress resistance ability,and Roegneria kokonorica,Roegneria grandiglumis,Agropyron cristatum,and Elymus breviaristatus cv.Tongde are next,consecutively.Roegneria kokonorica,Roegneria grandiglumis,Agropyron cristatum and Elymus breviaristatus cv.Tongde were belonged to one group in the cluster analysis.