Soil Application of Boron and Zinc Influence Fruit Yield and Quality of Satsuma Mandarin in Acidic Soils

Boron and Zn deficiency are frequently observed in citrus planted in acidic soil. The study was conducted to determine whether soil application of B and Zn could improve citrus yield and fruit quality. Field experiments were conducted over a 3-yr period. The effect of soil application of B and Zn alone or in combination on the B and Zn absorption, yield, and fruit quality of Satsuma mandarin (citrus unshiu Marc.) were investigated on a yellowish-brown acidic soil (Haplic Luvisols). The soil available B and Zn concentrations were raised by application of B and Zn, respectively. Applying B increased the B concentrations in leaf, flower and fruit, whereas applying Zn had no obvious influence on leaf or fruit Zn concentrations until the third year. The yield increased with the B and Zn + B applications due to the increase in the number of fruit per tree in 2012. Applying B alone had no significant effect on quality, whereas applying Zn or Zn + B led to higher total soluble solid (ISS) and titratable acid (TA) contents in 2012. The fruit vitamin C content increased significantly with the application of Zn + B. Therefore, B and Zn affect fruit yield and quality differently in acidic soil. The citrus yield was mainly affected by B, whereas fruit quality was improved by Zn. A continuous combined application of B and Zn over a 3-yr period resulted in a higher yield and quality of Satsuma mandarins.