Screening And Studying Of Seedings Substrate With Functional Microorganism

With extensive applications of plug seedling technology,the market requirement for seedling substrate increases rapidly.Peat is a kind of available substrate material with wide applications both in the domestic and overseas.It is an unrenewable and expensive resource.The aim of this study is to choose low-cost raw materials to take the place of peat and use them to develop substrate materials which are suitable for cultivating vegetable seedlings.In this study,cow dung compost and vinasse compost were selected as the main raw materials,supplemented with vermiculite,the proper substrate formula ratio was tested for raising seedlings of watermelon,cucumber and tomato.The optimal substrate formula was selected by measuring the physical and chemical properties of different ratio substrates,and according to the growth of watermelon,cucumber and tomato.In order to reduce the cost of seedling cultivation,improve the efficiency of vegetable production,we used vinasse composts,cow dung composts to replace peat and vermiculite.To find the optimal parameters of functional substrate for secondary fermentation,the important parameters during fermentation process were optimized by designing single-factor and BBD experiments,then we selected optimal substrates as carriers and inoculated them with functional bacteria for solid secondary fermentation.Finally,according to the optimized parameters,the optimized functinal bacterial strains were inoculated into the substrates for solid secondary fermentation and applied the fermentation production to pot experiment.We applied the theory to practice and screened the composite microbial functional seedling substrates which can provide products and technical guidance for industry.The results of this study were shown below:The results showed that adding a certain amount of vermiculite into vinasse composts and cow dung composts decreased pH,electrical conductivity(EC)and aeration porosity of substrates.Two formulas which were vinasse composts,cow dung composts,vermiculite was 65:15:25(V:V:V,T5)and vinasse composts,cow dung composts,vermiculite was 70:10:20(V:V:V,T6)showed advantages in the physical and chemical properties.The growth indexes of watermelon,cucumber and tomato seedlings were significantly correlated with the available N,electrical conductivity(EC)and available K in the substrates,and the correlation with available N was the highest.In addition,the growth of seedlings in T5 and T6 was better than other eight treatments based on the physiological index of seedlings,such as root and stem volume,fresh weight of one hundred seedlings,the root activity and chlorophyll content.For 26 d-growing watermelon,the root volume and fresh weight of one hundred seedlings in T6 was the highest,which were 91.3 mm3 and295 g,followed by T5 treatment,which were 80.8 mm3 and 283 g.While for cucumber and tomato seedings,the indicators of T5 treatment were greater than other treatments(the root volume,fresh weight of one hundred seedlings in cucumber were 70.9 m13,193.g;the root volume,fresh weight of one hundred seedlings in tomato were 78.6 mm3,146.7 g).For cucumber seedling experiment,the total chlorophyll content of T5 was 2.32 mg·g-1,and root activity was 256.4 mg·g-1·h-1,which were all higher than other treatments,but there was no significant differences with T6.For different kinds of fruit and vegetable seedlings,T6was the best formula for watermelon;T5 was more suitable for cucumber and tomato.According to the biological characteristics(phosphorus solubilization,pH value,siderophore production,IAA equivalent synthesis and the root colonization)of seven functional bacteria,the optimized strain composition H69+A6 werescreened out.This funtional bacteria composition showed advantages in both production of different in vitro traits and rhizosphere colonization.The triangular flasks were used to conduct solid fermentation.We added 40g optimized substrate in each 250 mL flask and adjusted the pH to 6,then intermittently sterilized them in 121 ? for 30 minutes twice.The frequency of turning over and initial moisture content of substrates had significant effects on the bacterial survival.The reciprocal terms also had significant effects on the bacterial survival.The regression coefficient(R2)was 0.9884,which indicated that the regression equation had a high correlation and a well fitness,and could better describe the relationship between each factor and the response value.The effect of three factors on the survival of bacteria in the substrate was that the initial water content(X2)>the time interval(X1)>the fermentation temperature(X3).The optimal parameters of the substrate(formulas which were vinasse composts,cow dung composts,vermiculite=65:15:25(V:V:V,T5))was as follows:when the fermentation period was 5 d,initial inoculation levels was 10%,time of rollover interval was 24.84 h,the water content was 60%,temperature was 33.25?,the survival bacterial got the highest.The number of bacteria in the substrate was 9.24(Log10CFU·g-1DW)under the optimal conditions.According to the optimal conditions,inoculated the functional bacteria into the substrates,and the microbial functional seedling substrates were formed by secondary solid fermentation.In the tomato potting experient,the results showed that comparing with the other treatments,the microbial functional seedling substrate increased by 9%,47.9%,27.3%and 28.7%with the emergence rate,dry weight of shoot and root,root activity.stem diameter of seedlings increased by 28%,indicating that functional microbial substrate enhances seedlings to get a stronger resistance and adaptability.