| Trichoderma guizhouense NJAU 4742,as a well-known bio-control fungus,is widely distributing in soil,which also has the ability to promote plant growth increasing crop yield and quality.However,there are few studies focusing on its capacity in solubilizing sparingly-soluble minerals or its effect on plant growth which grown in nutrient-limiting soils.The objectives of this study were 1)to investigate the contribution of NJAU 4742 to P and microelement(Fe,Mn,Cu and Zn)nutrition in tomato plants grown in soil and in hydroponic conditions,2)to underline the possible mechanisms involved in this progress and 3)to test the impacts of Trichoderma-enriched biofertilizer on the growth of saline-alkali soil cultivated tomato.The results were shown below:1.NJAU 4742 was able to solubilise phytate,Fe2O3,CuO,and metallic Zn but not Ca3(PO4)2 or MnO2.Organic acids,including lactic acid,citric acid,tartaric acid and succinic acid,were detected by HPLC and LC/MS in SY and glucose liquid culture filtrates.Titratable acid analyses showed an increase of titratable acid and a decrease of pH values(from pH 5.4 to pH 4.3)in glucose liquid culture filtrates.Phytate solubilisation,Fe chelation and Fe reduction were estimated quantitatively after incubation from the 0th to the 9th day.The production of siderophores in the SS cultures increased up to 56%over time compared with the uninoculated controls(CK).The absorption spectrophotometry analysis of ferric reductase release showed that the absorbance of the SS cultures increased over time(from 0.03 up to 0.16).The soluble P in Trichoderma culture filtrates(SS)rapidly increased and reached its peak value,until the death of hypha.2.The population of Trichoderma in tomato rhizospheric soil was 3.0×104 cfu per gram of dry soil,as measured by dilution plating.The pot experiments showed that inoculation with T.guizhouense NJAU 4742 significantly(P<0.05)affected the biomass and nutrient uptake of tomato seedlings.The seedling dry weight increased by 31%,and K,Fe and Zn uptake increased by 15-40%in the tomato shoots;the uptake of P,Fe,Cu and Zn by the roots was also higher(21-73%)than in the uninoculated control.Compared with the uninoculated controls(CK),the available Fe,Mn and Cu nutrient contents have significant effect of the SS treatment.3.We initiated a P-deficient hydroponic experiment,in which tomato seedlings were grown in a P-deficient nutrient solution supplemented with a solid phytate supply.In these conditions,we observed a significant decrease in plant biomass(82%,dry weight)in NJAU 4742-inoculated plants(SS)compared to uninoculated control plants(CK)(P<0.01).A prominent effect of NJAU 4742 inoculation(SS)was found on the growth of tomato seedlings grown in Cu-deficient hydroponic conditions.Moreover,root analysis suggested in the P-deficient condition,the tomato root surface area,the root volume and the numbers of root tips were increased by NJAU 4742 inoculation.By contrast,nearly the opposite phenomenon of root development was found in the Zn-deficient condition.All parameters of root development following SS treatment in the Fe-deficient and the Cu-deficient conditions were improved compared to the control(CK),although no significant difference in the root length in the Fe-deficient condition and the root surface area in the Cu-deficient condition was observed between the SS-treated and control plants.4.In the field trials,compared to the 100%conventional chemical fertilizer treatment(CF),a reduced application of chemical fertilizer(75%of the conventional application)plus Trichoderma-enriched bio-organic fertilizer(BF)increased the tomato yield by 15.44%,and improved the fruit quality.Also,BF enhanced the activities of soil urease,phosphatase and catalase.During the flowering and harvesting time,the activity of soil ferric reductase improved significantly(p<0.05)in the BF treatment.The available P and microelements in BF-treated and organic-fertilizer-treated soils increased significantly. |
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