| Mango(Mangifera indico Lin)and banana(Musa Nana low)are the main planting fruit trees in tropics of China.They have also become the pillar industry of agriculture in tropical crop areas of China.Due to the excessive application of chemical fertilizer,the soil in tropical crop area of China is facing a series of problems such as soil acidification,compaction,decreased fertility and frequent occurrence of soil borne diseases,which has led to the gradual decline of economic efficiency of mango and banana planting and seriously hampered sustainable development of the mango and banana industries in the tropical crop areas.A lot of researches showed that the application of bio-organic fertilizer could reduce improve the soil structure,fertilize the soil and accelerate the release of soil nutrients.Meanwhile it also can promote the growth of plants,improve the yield and quality of crops.Therefore,this study used dilution counting method and plate antagonistic confrontation to isolate thermotolerant Trichoderma strains with certain promoting and biocontrol effects from the tropic crop soil.And then bio-organic fertilizer was developed using the isolated Trichoderma strains and used in greenhouse experiment to-screen the best plant growth promotion strain.Finally,the effect of bio-organic fertilizer containing the Trichoderma strain on the growth of mango and banana in tropic crop areas and its effect on soil microorganism was evaluated under field condition.The main results are as follows:1.A total of 60 Trichoderma strains were isolated and screened from mango and banana orchards soil samples in tropic crop areas and these strains belongs to 8 Trichoderma species when identified by ITS(Internal Transcribed Spacer)sequence analysis.By observing the growth of Trichoderma at different temperatures,it was found that all Trichoderma strains could grow at 20-28℃,but only 13 Trichoderma strains could grow at 35-40℃.The growth diameter of these 13 strains was large at 35℃ and 40℃,but was small at 20℃.The results of plate confrontation test with Fusarium oxysporum f.sp.cubense race(FOC4)showed that the antagonistic ability of strain MD30(Trichoderma longibrachiatum)and JS84(Trichoderma citrinoviride)to FOC4 was 48.4%,48.9%and 49.7%respectively at 20℃,and that of strain JS84 was 47.6%at 28℃.The activity of enzyme secreted by the strain at different temperatures showed that the ability of producing cellulase and chitinase of strain JS84 significantly increased under the conditions of low temperature(20℃)and high temperature(35℃ and 40℃).The activity of producing chitinase and β-1,3-glucanase of strain MD30 significantly increased,and the activity of producing β-1,3-glucanase of strain JS84 significantly increased under the conditions of high temperature(35℃ and 40℃).2.The results of two seasonal pot experiments showed that the application of bioorganic fertilizer made from strain MD30 and JS84 could effectively promote the growth of cucumber seedlings and improve the soil fertility.In the first season,compared with control(CK),treatment of application of chemical fertilizer(CF),treatment of application of organic fertilizer(OF)and treatment of application of bio-organic fertilizer containing Trichoderma NJAU4742(4742),both treatment of application of bio-organic fertilizer containing Trichoderma JS84(JS84)and treatment of application of bio-organic fertilizer containing Trichoderma MD30(MD30)significantly increased the fresh weight and dry weight of cucumber shoot.In the second season,the plant height of cucumber for treatment of JS84 was significantly higher than that of CK,CF,OF,4742 and MD30 treatments,which was increased by 140%,59%,39%,36%and 34%,respectively.And the fresh weight of cucumber shoot for treatments of both MD30 and JS84 was significantly higher than that of CK,CF and OF treatments,among which was increased by 116%、28%and 15%,respectively for MD30 and,135%,40%and 25%,respectively for JS84.Both MD30 and JS84 treatments displayed a significant higher content of soil organic matter and nitrate nitrogen,and a higher abundance of soil total bacteria and fungi.3.The results of field experiment showed that the application of bio-organic fertilizer containing Trichoderma MD30 and JS84 could effectively improve the yield and fruit quality.Under the conditions of equal nutrient settings for each treatment,treatment of application of 8 kg of bio-organic fertilizer containing Trichoderma MD30 per mango tree(MD30)exhibited a higher yield compared to control(CK),treatment of application of chemical fertilizer(CF)and treatment of application of organic fertilizer(OF),which showing a 13%,7%and 6%increase,respectively.Compared with other treatments,MD30 treatment significantly increased the average weight of single mango,the weight of commercial fruit,and the content of total soluble solid and reducing sugar in mango fruit.Meanwhile,MD30 treatment showed a significant higher contents of total phosphorus and available phosphorus and a higher abundance of total soil bacteria and fungi.Under the conditions of equal nutrient settings for each treatment,treatment of application of 8 kg bio-organic fertilizer containing Trichoderma JS84 per banana tree displayed a significant higher yield compared to CK,CF,OF and 4742 treatments,which showing a 32%,18%,8%and 6%increase,respectively.Compared to CK,JS84 treatment showed a significant higher content of edible rate and total soluble solid,vitamin C,reducing sugar and protein in banana fruit.JS84 treatment also showed a significant higher contents of soil available phosphorus,available potassium,and nitrate nitrogen.Moreover,JS84 treatment also showed a significant higher abundance of total soil bacteria and fungi and a lower abundance of Fusarium oxysporum.In summary,Trichoderma longibrachiatum MD30 and Trichoderma citrinoviride JS84 can grow faster at 20-40℃,with strong antagonistic ability and high enzyme producing activity.And bio-organic fertilizer developed based on this two isolated Trichoderma strain could effectively promote crop growth,increase fruit yield and improve fruit quality,and improve soil nutrient and soil biological activity,which could support sustainable development of agriculture. |
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