Effect Of Trichoderma On Chinese Wolfberry Under Salt Stress And Application Of Trichoderma Fertilizer In Saline-alkali Soil

There are vast coastal saline-alkali soil area in the Yellow River Delta with high salinity and low soil nutrients,which seriously affects the development of local agriculture,especially cash crops.The application of microbial agents is an effective measure for improving saline-alkali soil.Trichoderma is an ideal strain for preparing bacterial fertilizer and agent because of its superior characteristics for improving soil environment and promoting plant growth concurrently.Chinese wolfberry(Lycium chinense)has strong salt and waterlogging resistance,is suitable to be planted in coastal saline-alkali soil area in order to obtain economic benefits.Studying the influence mechanism of Trichoderma on the salt resistance of Chinese wolfberry can promote the survival and growth of Chinese wolfberry in saline soil,in order to provide theoretical basis for the cultivation of Chinese wolfberry in coastal saline alkali soil area and realize the green development of the Yellow River Delta.In this study,a Trichoderma strain isolated in the early stage was used to evaluate the possibility of its application in bacterial fertilizer and agent by analyzing its salt tolerance and characteristics in promoting plant growth.In order to prepare Trichoderma fertilizer and agent which can be used in the experiment,the fermentation conditions were optimized by orthogonal test.The protective effects of Trichoderma on ion balance and PS? of Chinese wolfberry under salt stress were studied by designing pot experiments,revealing the mechanism of Trichoderma for improving the salt resistance in Chinese wolfberry.We further studied the growth promoting effect of Trichoderma fertilizer and agent on Chinese wolfberry in saline soil.Finally,the field experiment was designed to study the effect of Trichoderma fertilizer and agent on improving coastal saline alkali soil and promoting the growth of Chinese wolfberry under field conditions.The main experimental results are as follows:1.Study on growth promoting characteristics of Trichoderma and preparation of Trichoderma fertilizer and agentThe salt tolerance and growth promotion characteristics of the strain were determined in order to study the possibility of our Trichoderma strain obtained in the early stage applied to the growth promotion of crops in saline alkali soil.The result showed that the strain could still grow hyphae under the condition of 1000 mmol·L^-1 NaCl,indicating it has strong salt tolerance.In the meantime,the strain has strong ability to secrete ferritin and ACC deaminase,dissolve inorganic and organic phosphorus,and secretes a few of IAA.So it is suitable for applying to saline alkali soil.The results of multi factor orthogonal test showed that the optimal fermentation conditions of Trichoderma fertilizer were 20%inoculation,2.5%wheat bran content,28?fermentation for 15 days,and the optimal fermentation conditions of Trichoderma agent were 1%KH₂PO₄,20%inoculation,60%humidity,25?fermentation for 4 days.The living bacteria count of Trichoderma fertilizer can reach 2×10~8 CFU/g,the number of spores of Trichoderma agent can reach 3×10¹⁰ pieces/g,both of them can meet industry standards and be used in subsequent application experiments.2.Effects of Trichoderma on root and leaf ionic homeostasis and PS? in Chinese wolfberry under salt stressThe effects of Trichoderma on ion transport process and photosynthetic mechanism of Chinese wolfberry under salinity were studied by pot experiment.The results showed that under 300 mmol·L^-1 NaCl stress,Trichoderma significantly enhanced the Na⁺efflux in root and the aboveground transport of Chinese wolfberry,increased K⁺absorption,maintained ion balance in the plant,reduced the damage of ion toxicity and oxidative stress to PS?,protected photosynthesis and reduced biomass loss.3.Growth promoting function of Trichoderma fertilizer and agent on Chinese wolfberry in saline soilA pot experiment was conducted to study the growth promoting effect of Trichoderma fertilizer and agent on Chinese wolfberry in medium salinity barren soil.The results showed that Trichoderma in fertilizer could regulate the absorption and transport of K⁺,Na⁺and water,alleviate the oxidative stress caused by osmotic stress and ion toxicity,and maintain plant photosynthesis.But these effects were not lasting,which showed as the photosynthetic performance of plants decreased significantly in the later stage of culture.The organic matter in Trichoderma fertilizer can enhance the plant absorption of nutrients(especially K⁺)and promote chlorophyll synthesis,but the effect is relatively slow as well as the effect on leaf relative moisture content and Na⁺transport is not significant.The effect of Trichoderma fertilizer was always better than Trichoderma agent or single fertilization,and the photosynthetic performance of plants was not significantly decresed during the treatment,which indicated Trichoderma fertilizer has a stronger ability of promoting growth.4.Effect of Trichoderma fertilizer and agent in coastal saline alkali area of the Yellow River DeltaThe field experiment was designed to study the application effect of Trichoderma fertilizer and agent in coastal saline alkali soil.The results showed that Trichoderma fertilizer can significantly improve soil water holding capacity,improve soil structure and increase nutrient content in soil,which means it could improve coastal saline soil environment to a certain extent.In the same time,it can regulate plant water absorption,ion accumulation and photosynthesis,reduce oxidative stress and significantly increase plant biomass and yield.The effect of Trichoderma agent is not as good as Trichoderma fertilizer,but it still has a certain regulation ability without applying exogenous nutrients.