Preparation Of Fish Protein Polypeptide And Its Application In Agricultural Production

China is rich in marine fishery,and has ranked highest in fishery output in the world.In recent years,with the rapid development of aquatic products processing,the production of low-value fish waste(hairtail,small yellow croaker)is increasing.The protein in low-value fish wastes is higher and cheaper,which is an excellent protein source with great potentatial of utilization.At present,a small proportion of low-value fish waste is used to produce the biological feed and compound seasonings,but most of them are not fully utilized and often treated as waste,resulting in a large number of fish protein waste and environmental pollution.An extensive body of research has demonstrated that exogenous peptides,as a new plant hormones apart from the five kinds of plant hormones(gibberellins,auxins,abscisic acid,cytokinins and ethephon),play an important role in promoting plant growth,raising the yield of crops and improving fruit quality,enhancing crop stress resistance.Therefore,to investigate the effects of fish protein polypeptide on plant growth,and its application has important guiding significance in agricultural production.Among the various methods of proten hydrolysis,enzymatic method has excellent properties such as mild reaction condition,strong specificity,easy control,no toxic products and so on.With aquatic product residues as raw materials,using of the protease hydrolysis to produce high value-added products has become one of the main trend of the current aquatic products processing industry.Proteases are biologically active substances,which are used widely in industrial production.Thus using proteases to hydrolyze low-value fish wastes into peptides can reduce environment pollution and improve the comprehesive ultilization of aquatic processing waste.In this paper,the effects of fish protein polypeptide on the seed germination of three vegetables(pepper,tomato and brinjaul)under salt stress,the effects of fish protein polypeptide on sweet-waxy maize seed germination and seedling growth under salt stress,the addition of fish protein polypeptide in substrate increases growth of cherry tomato plug seedlings in greenhouse were studied.With the method of compound enzyme hydrolysis,produce fish protein polypeptide from aquatic product residues and the effects of fish protein polypeptide on seed germination of three vegetables seeds(pepper,tomato and brinjaul)under 100mmol/L NaCl stress was explored.The optimal technology conditions were multi-enzyme 3.7%(E/S),52?,pH6.8,when neutral protease and flavourzyme were adopted together with a ratio of 1 to 3.When aquatic product residues was hydrolyzed for 360 min,the hydrolyzing degree of protein reached 41.41%,78.73%(w/w)of fish protein polypeptide with 76.82% purity under these conditions.Germination rate,germination energy,germination index and vigor index showed a trend of rising in varying degrees when of three kinds of vegetable seeds(pepper,tomato and brinjaul)were soaked with 0.1%-0.7% fish protein polypeptide under salt stress.However,the study found remission effect of 0.5% fish protein polypeptide was the best optimum.These results indicated that three vegetable seeds pretreated by fish protein polypeptide could effectively ease the damage caused by salt stress.In order to illustrate the alleviating action of fish protein polypeptide to sweet-waxy maize under salt stress,the effects of different concentrations(0,0.2%,0.4%,0.6%,0.8%)of fish protein polypeptide on seed germination and seedlings under the treatment of 150mmol/L NaCl were studied by using sweet-waxy maize ‘Jing kenuo 2010' as the test material.The result indicated that the germination rate,germination energy,the biomass of sweet-waxy maize seedlings showed a trend of rising in varying degrees compared with salt treatment group,under the preliminary condition of different concentrations fish protein polypeptide.The chlorophyll content(chlorophyll a,chlorophyll b,chlorophyll a+b)and antioxidant enzyme activity(SOD,POD,CAT)increased significantly,but the content of MDA decreased significantly after spraying fish protein polypeptide on the leaves in the appropriate concentration.However,the study found the optimum concentration of fish protein polypeptide was 0.6%.These results indicated that fish protein polypeptide can effectively alleviate the inhibition of salt stress and increase salt tolerance of sweet-waxy maize seeds and seedlings.In this study,the effect of different amount of fish protein peptide on cherry tomato plug seedling was studied by using ‘cherry tomato' as the test material,which will provide a theoretical reference for the application of fish protein polypeptide in plug seedling production.The results showed that plant height,stem diameter,dry weight of shoot and root,root to shoot ratio,health index,chlorophyll content(chlorophyll a,chlorophyll b,chlorophyll a+b),root activity of plug seedling showed a trend of rising in varying degrees compared with control group.However,the study found the optimum addition of fish protein polypeptide was 10g/L.Comprehensive analysis indicated that appropriate addition of fish protein polypeptide can promote the growth of cherry tomato plug seedlings.