Variations of mineral elements contents in Sijiyou pummelo leaves and fruits during the development period

As an important part in fruit cultivation, fertilization becomes one of the most effective technologies to improve yield and quality of fruit. Combination with plant nutrition diagnostic techniques, the theory of mineral nutrition with fertilization techniques on fruit production was applied to understand surplusdeficit status of nutrient elements at fruit growth period of Sijiyou pummelo ［Citrus grandis (L.) Osbeck］ and to provide theoretical basis for the nutritional regulation and rational fertilization application. The contents of mineral elements in Sijiyou pummelo leaves and fruits at the fruit development period were measured to study their variation characteristics and correlations. The research was carried out in plants of over 40 years old in Sijiyou pummelo production base in Zhejiang province since 2009 The results show that during the development of leaves, the N and P contents decreased gredualy, the K, Ca, Mg, B and Zn contents increased in the early phase and decreased later, and the S content increased on the whole. The Fe content decreased gradually in the early phase, then steady, and increased later. The Cu content vept stable, and the content of Mn increased and then decreased, and finally increased. In the development of fruits, the N, P, K, Ca and S contents present downward trends all along, the Mg content increased at the early phase and decreased later, the Fe and Mn contents kept relatively stable, and the contents of B, Zn and Cu slightly different at the development period. The level of collaborative absorption of mineral elements was week between fruits and leaves, but strong between flesh and peel. Relatively high N and P fertilizer rates should be used before the budding, proper amount of Ca fertilizer in mid-June, K and Mg fertilizers in mid-July should be applied, and microelements fertilizer application should be emphasized.