Influence Of Seaweed Functional Water Soluble Fertilizer On Drought Resistance,yield And Quality Of Chinese Cabbage Under Drought Stress

Drought stress is a significant factor that limits the production and quality of crops.Seaweed extract contains many physiological active substances which plays an important role in enhancing the drought resistance of crops.In this paper,four kinds of processing technologies of seaweed extract were compared.And then a kind of seaweed functional water soluble fertilizer was prepared with the seaweed extract made by the method of compound hydrolysis.On these bases,influence of the seaweed functional water soluble fertilizer on drought resistance,yield and quality of Chinese cabbage under drought stress was discussed.The main results were shown as follows:1.The processing rate,viscosity,concentrations of several chemical components of four kinds of seaweed extract respectively made by methods of acid hydrolysis,alkaline hydrolysis,enzymatic hydrolysis and compound hydrolysis respectively were compared.The seaweed extract made by compound hydrolysis method was found had the highest processing rate and lowest viscosity,which were 80.67% and 1.57 mpa·s respectively.Besides,it also contained the highest contents in soluble solids,alginate and reducing sugar,etc.The parameters of the enzymatic hydrolysis step in compound hydrolysis method were also optimized,the seaweed extract had the highest alginate content when the enzymolysis temperature was 40 ?,the enzymolysis time was 20 hours,the enzymolysis pH was 7.0,the adding amount of compound enzyme was0.1%,and the concentration of alginate was more than 20 g/L.A kind of seaweed functional water soluble fertilizer was manufactured by the seaweed extract made by compound hydrolysis method.2.Results from a pot experiment showed the biomass of Chinese cabbage treated by seaweed functional water soluble fertilizer were increased by 86.27% when compared with control treatment under drought stress.However,the biomass,soluble sugar,vitamin C,and soluble solids were increased by 33.62%,25.66%,18.37%,20.58% respectively when compared with equal nutrients compound fertilizer in the same environment.3.The experiment about effect of seaweed functional water soluble fertilizer on water-retaining showed that the moisture content of the soil treated by seaweed functional water soluble fertilizer was increased by 11.94%~16.94% compared with control treatment,equal nutrients compound fertilizer and water soluble fertilizer when the dosage was 4% of the soil mass.What is more,when compared with control treatment under drought stress,seaweed fertilizer could increase Chinese cabbage leaves antioxidant enzyme activities including SOD,POD,CAT,APX by 61.29%,37.61%,53.12%,15.02% respectively.These results revealed the drought resistance of the seaweed functional water soluble fertilizer.4.Seaweed extract was divided into components that molecular weight are more than 10 KDa,between 5 KDa and 10 KDa,between 3 KDa and 5 KDa,less than 3KDa respectively by ultrafiltration centrifugal technology.The efficiency of these components to understand free radicals were compared in vitro,and the component that molecular weight is less than 3 KDa was found had highest clearance rates for hydroxyl radical and superoxide anion which were 46.67% and 25.89%.Results from the water culture experiment showed that the component that molecular weight is less than 3 KDa could improve the biomass and plant relative water content of Chinese cabbage seedling by 36.23% and 5.11% in drought environment.It's worth mentioning that the component that molecular weight is less than 3 KDa contained higher levels of alginate,algae polyphenol and mannitol and so on.5.Results from the field experiment showed that seaweed functional water soluble fertilizer could promote the economic output of Chinese cabbage by 19.81%and 18.72% in Guangdong and Ningxia in drought circumstance,and the quality indicators,such as soluble sugar,soluble protein were also increased when comparedwith equal nutrients compound fertilizer.Furthermore,whether it was in well-watered or water-stressed environment,seaweed fertilizer reduced by 20% dosage would not shortened the economic output neither nor the quality index of Chinese cabbage.The above results showed that seaweed functional water soluble fertilizer could enhance the drought resistance of Chinese cabbage and promote the yield and quality.One of the mechanism may is that seaweed functional water soluble fertilizer increased the moisture content of the soil under drought conditions.And another may is that seaweed polyphenol,mannitol or other functional substances gathering in the part that molecular weight is less than 3 KDa in seaweed extract induced the drought resistance of Chinese cabbage.