Effects of combined organic/inorganic fertilizer application on growth, photosynthetic characteristics, yield and fruit quality of Actinidia chinesis cv ‘Hongyang’

In China, Hongyang Kiwifruit (Actinidia chinesis) is considered to be economically valuable because of its appealing red flesh, unique flavor and beneficial metabolites. A continuous 3-year field experiment was conducted in a private orchard in Dujiangyan, Sichuan Province, China, to determine the effect of different NPK ratios and organic fertilizer application on growth and yield. Approximately 162 vines were selected in a completely random design with nine fertilization treatments (PK; NK; NP; NPK; 2NPK; N2PK; NP2K; NPK + OM (organic matter)). Data on leaf number, leaf area, stem diameter, photosynthetic parameters, leaf N, P and K, chlorophyll content, yield and fruit quality were collected from individual kiwi vines for each treatment during the years 2011–2013. The application of inorganic fertilizer significantly increased fruit yield, leaf number, and leaf area and stem diameter increment as well as leaf photosynthetic rates and the concentrations of N, P and K in the leaves. However, the fruit yields were reduced in the unbalanced fertilizer treatments, NP, NK, and PK and in excess nutrient treatments, 2NPK, N2PK, NP2K, in contrast to the optimum NPK treatment. This was due to lower leaf photosynthetic rates and fewer photo-assimilates being available to the fruit. Moreover, the addition of organic fertilizer along with inorganic fertilizer (optimum NPK) did not increase plant growth, photosynthetic rates or fruit yields compared with only NPK fertilizer application, but significantly enhanced the fruit quality as a result of improving fruit chemical composition, such as soluble solids and reduced sugar.