| Trichoderma is a filamentous fungus widely distributed in the soil,which has strong antibacterial ability,promoting plant growth and development and improving plant disease resistance.At the same time,it can regulate the soil microbial environment and relieve salt stress in the soil.Therefore,Trichoderma is widely used in soil improvement,ecological environment restoration and disease control.Cowpea,one of the delicacies on people’s table,can not only adjust the skin and nourish the body,but also has the effect of invigorating the stomach and invigorating the kidney.However,along with the excessive use of chemical fertilizers and continuous cropping,the issue of soil salinization and soil-borne diseases of Fusarium wilt,have been becoming more and more serious,which poses a certain threat to cowpea production.In this study,Trichoderma was isolated from the saline soils of Gansu,Qinghai,Heilongjiang and Ningxia,and tested for salt tolerance and antagonistic effects against Cowpea Fusarium Wilt to screen out Trichoderma with strong salt tolerance and antagonism.And,this study also carried out the evaluation of Trichoderma on alleviating adverse effects of salinity,promting growth and controlling Cowpea Fusarium Wilt in cowpea.The main results are as follows:1.Using the dilution plate method,64 strains of Trichoderma were isolated from saline-alkali soils in Gansu,Qinghai,Heilongjiang and Ningxia,and then all the strains were cultured in 2 %,4 %,6 %,8 % Na Cl medium separately to screen out the salt tolerance strains.8 strains of Trichoderma(HL167,HL05,HL07,GS04,QH03,QH05,NX08,NX11)can grow and produce spores in 8 % Na Cl medium,among them,only strain HL167 can normally produce green spores on salt-containing plates and its sporulation could cover 3/5 area of the colony,while other Trichoderma strains produce discolored white and yellow spores,and its sporulation cover only 1/5 area of the colony,indicating that HL167 has strong salt tolerance.At the same time,the plate confrontation method was used to detect the antagonistic effect of all strains on Fusarium oxysporum,showing that Trichoderma strains NX044,NX022,QH100 and HL167 have a strong inhibitory effect on F.oxysporum,and the inhibition rate of HL167 strain against F.oxysporum was 73.08 %.The above results indicate that Trichoderma HL167 not only has good salt tolerance but also a strong inhibitory effect on F.oxysporum.2.Through the method of morphological observation,the phylogenetic tree of TEF1 and RPB2 sequence,the HL167 strain was identified as T.longibrachiatum.3.The salt-relieving and promoting effect of T.longibrachiatum HL167 on cowpea was analyzed through a greenhouse pot experiment.The results showed that compared with salt stress alone(200 m M Na Cl),the plant pretreatmented with T.longibrachiatum HL167 under salt stress(200 m M Na Cl)got the result that its plant height and root length were increased significantly,the content of chlorophyll(chlorophyll a,chlorophyll b,and total chlorophyll),the content of soluble protein,the activity of POD enzyme and CAT enzyme were increased significantly,but the content of MDA content was decreased.The result indicated that the plant pretreatmented with Trichoderma can increase the photosynthesis of plants and reduce the damage to plants caused by salt stress.4.The result of field control experiment showed that the control effects of Cowpea pretreatmented with T.longibrachiatum HL167 and then inoculated with the pathogen was62.39%;the control effects of Cowpea inoculated with the pathogen first and then treatmented with T.longibrachiatum HL167 was 41.88%;when cowpea was treatmented with carbendazim,the control effect on cowpea wilt was only 30.77 %.The result indicated that Trichoderma is better than the traditional pesticide carbendazim in preventing and controlling Cowpea Fusarium wilt,and the preventive effect of Trichoderma on cowpea is better than the curative effect.The above experiments showed that T.longibrachiatum HL167 can not only effectively relieve the stress of salt on cowpea to promote the growth of cowpea,but also has a better control effect on cowpea wilt,indicating that it could be applied to cowpea production in reality. |
