Effects of Foliar Spraying of Polypeptides on Schima superba Seedlings and Their Physiological Characteristics

To improve the microbial environment within plants and enhance the quality of Schima superba Gardn.et Champ.stands,this study aimed to investigate the effects of peptides on the internal environment of S.superba by exogenously applying a peptide(KRGREEDSLPNSPKRFHGET RRRKKLFKKILKYL(-NH₂)).Three-year-old S.superba seedlings were treated with foliar sprays of the peptide solution.A stock solution was prepared at a concentration of 1 mg·mL^-1 using double-distilled water.The treatments included T₁(sprayed with a 500-fold dilution of the peptide solution)and T₂(sprayed with a 1000-fold dilution),while the control group(C)was sprayed with double-distilled water.Parameters such as seedling height,ground diameter,endogenous hormone levels(gibberellin,auxin,abscisic acid and brassinosteroid),nutrient element content(N,P,K)and nutrient substance content(total soluble sugar,total soluble protein and total fat)were analyzed across the three groups.The results showed that the seedling height and ground diameter in treatment T₁ were significantly higher than those in the control group C and treatment T₂(P<0.05).The average levels of gibberellin,abscisic acid and brassinosteroid in treatment T₁ were significantly higher than those in group C and treatment T₂(P<0.05).Additionally,the contents of N,P,K,total soluble sugar and total soluble protein in the leaves of treatment T₁ were significantly increased(P<0.05).The findings indicate that exogenous application of an appropriate concentration of the peptide promotes the growth and development of S.superba and enhances its stress resistance.