Spraying Foliar Fertilizer Affects Leaf Physiological Function and Improves Fruit Quality of ‘Ganshi 84-8’ Camellia oleifera Abel

Abstract

Foliar fertilization can supplement nutrients efficiently. We screened foliar fertilizers suitable for Camellia oleifera to improve leaf photosynthetic function, and enhance fruit yield and quality. Ten-year-old C. oleifera ‘Ganshi 84-8’ trees were used as experimental material, and the effects of different combinations of potassium dihydrogen phosphate (KH 2 PO 4 ), boric acid (H 3 BO 3 ), and brassinosteroids (BRs) were evaluated. Our results show that all foliar fertilizer treatments increased fruit set rates to varying degrees. In addition, these treatments exhibited differentiated improvements in fruit yield and quality parameters. Specifically, treatment 1 (T1) and T4 increased the fresh seed kernel yield rate and yield per plant significantly, and T2 helped increase oil content and yield per plant, with increases of 7.32% and 32.20%, respectively, compared with the control. Although T3 reduced yield per plant significantly, it increased fruit longitudinal diameter notably. Treatments 5 and 7 increased the fresh fruit seed yield rate and fresh seed kernel yield rate significantly. Treatments 6, 8, and 9 increased primarily the fruit transverse and longitudinal diameters, and T8 also increased oil content by 9.63%. A comprehensive comparison indicated that T8 (2.4 g·L –1 KH 2 PO 4 + 0.8 g·L –1 H 3 BO 3 + 0.06 mg·L –1 BRs) exhibited the best overall effect, improving fruit quality and yield substantially. Our results provide a theoretical basis and scientific reference for improving the quality of C. oleifera .