The effects of inarching Citrus reticulata Blanco var. tangerine on the tree vigor, nutrient status and fruit quality of Citrus sinensis Osbeck 'Newhall' trees that have Poncirus trifoliata (L.) Raf. as rootstocks

Inarching is an agronomic technique to repair trees that have been girdled as a result of damage caused by mice, rabbits and other rodents as well as mechanical injury. In addition, inarching significantly influences the growth, productivity and quality of citrus trees. In the present study, field observations and laboratory experiments revealed that inarching nursery stock Citrus reticulata Blanco var. tangerine trees could affect the tree vigor, nutrient status and fruit quality of Citrus sinensis Osbeck 'Newhall' trees that have Poncirus trifoliata (L.) Raf as rootstocks. The results showed that the parameters related to tree vigor (circumference, height and diameter) and yield significantly increased in response to inarching. Moreover, the leaf contents of trace elements, including manganese (Mn), iron (Fe) and calcium (Ca), increased after inarching, while the contents of copper (Cu), zinc (Zn) and potassium (K) decreased. However, compared with those in the control (CK), the contents of magnesium (Mg), phosphorus (P), boron (B) and nitrogen (N) after inarching did not significantly change. In addition, fruit quality, the total soluble solids (TSS) content, the soluble sugar content (SSC) and the TSS/titratable acid (TA) ratio significantly decreased in the inarching treatment, while the TA, vitamin C (Vc) content, single fruit weight, fruit shape index and fruit mastication did not sigthficantly differ. Fruit flavor evaluations revealed that sourness, fruitiness and juiciness significantly increased after inarching, while sweetness and gumminess decreased. Taken together, these results provide a novel direction for improving the production of Citrus sinensis Osbeck 'Newhall'.