Changes in mineral nutrition during fruit growth and development of ‘Seike’ and ‘Newhall’ navel orange as a guide for fertilization

Abstract Changes in the accumulation patterns of mineral nutrients at different development stages of fruit reflect the requirements of citrus trees for different nutrients, and this information provides an essential reference for rational fertilization. In this study, changes in the contents of 11 nutrients in the whole fruit, fruit pulp, and peel were studied during the whole developmental period of the fruit of ‘Seike’ and ‘Newhall’ navel oranges. We found that the two navel orange cultivars showed very similar changes in nutrients. Specifically, the N, P, Mg, S, Mn, and Zn contents were high in the young fruit stage (April), the K and Fe contents were high in the fruit expansion stage (July and August), and the Ca content was high in the fruit maturation stage (October). As the fruit developed, the N, P, Mg, S, Zn, and B contents decreased to the lowest levels at fruit maturity in November. In addition, the contents of N, P, K, Fe, Zn, and Cu were ranked as fruit pulp > whole fruit > peel, while Ca, Mn, and B contents were ranked as fruit peel > whole fruit > fruit pulp. N, P, K, and Mg accumulated in the fruit in June and July, in contrast to the June to September period for the micro-elements. During these accumulation periods, it is recommended that suitable fertilizers be applied in a timely manner.