Soil application of calcium and magnesium fertilizer influences the fruit pulp mastication characteristics of Nanfeng tangerine (Citrus reticulata Blanco cv. Kinokuni)

• Fruit pulp mastication characteristic was related to the fruit pulp IDF and SDF.
• The fruit pulp IDF content was influenced by the fruit pulp P, Ca and B contents.
• The fruit pulp SDF content was influenced by the fruit pulp P and K contents.
• Fruit pulp mastication characteristic was improved by applying Ca and Mg fertilizers.

The objective of the present work was to examine the effect of soil-applied calcium (Ca) and magnesium (Mg) on the fruit pulp mastication characteristics of “Nanfeng” tangerine (Citrus reticulata Blanco cv. Kinokuni). A field experiment was conducted continuously in a red soil orchard from 2011 to 2013. Five fertilization treatments were involved; they were FF (farmer’s fertilization), RF (recommended fertilization), RF + Ca, RF + CaMg and RF + FMP (fused magnesium phosphate). In this study, the fruit pulp’s shear force and insoluble dietary fiber (IDF) contents of the RF + CaMg were significantly lower than those of the RF treatment, and fruit pulp’s boron (B) content and leaf potassium (K) and B contents were lower whereas the leaf Mg content was higher in the RF + CaMg treatment than in the other treatments. The fruit pulp’s shear force (higher shear forces meant inferior mastication characteristics) was significantly positively related with IDF but negatively related with the soluble dietary fiber (SDF). However, fruit segment shear force was significantly negatively correlated with fruit pulp N and P contents but positively with B content. We concluded that the fruit pulp mastication characteristic was significantly related to both IDF and SDF of the fruit pulp which were predominantly influenced by the fruit pulp B, P, Ca and K contents, so the mastication characteristic of NM fruit pulp could be improved by combining appropriate N, P and K fertilization rates with 500 g lime and 100 g magnesium oxide per tree.