Effects Of Seaweed Polysaccharides And Spermidine On The Growth Of Vegetables In Arbuscular Mycorrhizal Fungi

Arbuscular mycorrhiza(AM)is a reciprocal symbiosis formed by the microbial arbuscular mycorrhizal fungi(AMF)in the soil and the host plant roots of the vascular bundles.By combining with the root system of the host plant,the surface area of the root system is improved,and the material secreted by the mycelium is also beneficial to the degradation and utilization of the phosphorus element.AMF symbiates the growth and metabolism of plants in different forms,including increasing the growth of plant plants,improving the rhizosphere environment of the host plants and improving the mineral nutrition of the plants.In the meantime,it can also enhance the ability of plants to tolerate stress and protect against other harmful microorganisms,Besidesit has positive effects on increasing crop yield and improving fruit quality.However,the activity,the infection rate and the effectiveness of AMF will be inhibited by the relatively high level nutrient content in the seedling substrate.Therefore,it is important for the development of AMF-containing vegetable nursery substrate to find a way to improve the AMF infection rate and activity.Seaweed polysaccharides(SP)and polyamines(PAs)can regulate the growth and development of plants,including the promotion of growth,delay aging,and other physiological effects,which showed a positive effect on improving crop resistance,improving quality and so on showed a positive effect.In this study,chrysanthemum Gai Lan,lettuce,mustard,lettuce and other leafy vegetables and 'Jinchun 2' cucumber as material,by adding SP and Spd to AMF in the mixed substrate,to explore the methods and ways to improve the effect of AMF infection by exogenous additives,in order to improve the application effect of the organic substrate provides the theoretical basis.The main findings are as follows:1.The addition of SP and AMF significantly improved the dry weight,fresh weight and stem diameter of leafy vegetables,and increased the soluble sugar,soluble protein,nitrate nitrogen and total chlorophyll concentration of leafy vegetables.The results showed that the addition of SP and AMF could promote the growth of leafy vegetables,and the effects of SP and AMF on the growth and development of leafy vegetables were the highest.Vegetable growth has a superposition effect.2.The addition of Spd and AMF increased the root vigor of cucumber seedlings,promoted plant growth and increased fruit yield and quality.The results also showed that Spd could increase the infection rate of AMF,and there was a superimposed effect between themselves,which had the most obvious effect on the growth of cucumber.It is suggested that the addition of Spd in the substrate of AMF is an effective method to enhance the AMF infection rate.3.The addition of Spd and AMF enhanced the contents of chlorophyll a and chlorophyll b in cucumber seedlings,and improved the net photosynthetic rate of light plant(Pn),stomatal conductance(Gs),transpiration rate(Tr),stomatal limitation value(Ls),water use efficiency(WUE)decreased,intercellularCO2 concentration(Ci);but Spd and AMF increase cucumber leaves the apparent quantum efficiency(AQY),carboxylation efficiency(CE)and light respiration rate(Rp)decrease,dark respiration rate(Rday);Spd and AMF increase cucumber maximum photochemical efficiency(Fv/Fm),the actual photochemical efficiency(PSII),and quenching coefficient(qP),non photochemical quenching coefficient(NPQ),effective photochemical efficiency(Fv'/Fm')and electron transport rate(ETR).The results showed that the addition of Spd and AMF in organic substrate promoted the accumulation of photosynthetic pigments in cucumber plants,increased the net photosynthetic rate and light energy utilization rate of cucumber plants,decreased the decomposition of photosynthetic products,which promoted the accumulation of assimilation products.Moreover,AMF and Spd also enhanced the photosynthetic electron transport,and enhanced the light capture efficiency of cucumber plant PS ?reaction center,which promoted the growth of cucumber plants.4.The addition of Spd and AMF promoted the uptake of nutrient content of cucumber plants,increased the number of bacteria and actinomycetes in the rhizosphere substrate,and decreased the number of fungi.Spd and AMF also increased the activity of sucrase,neutral phosphatase of catalase and urease in the rhizosphere substrate.The results showed that Spd and AMF could enhance the uptake of plant nutrient,promote the transformation of rhizosphere microbial flora from "fungal type" to "bacterial type",improve the rhizosphere microbial diversity and maintain the stability of rhizosphere ecosystem.promote the growth of cucumber plants.