番石榴之營養及肥培管理

Abstract

番石榴係淺根性熱帶果樹，合理之肥培管理影零其產量及品質甚大。葉片分析結果，葉面增施磷肥，可逐漸增加葉面之磷含量，但對氮、鉀含量不受影響。季節間氮、磷、鉀和乾物量之濃度，以生育開始前及終止後濃度最高，而以果實完熟時最低，因此在產量顯著增加時，可噴施磷肥。番石榴葉片氮、磷、鉀之含量隨著葉齡之增加而滅少，枝梢頂端葉片氮、磷、鉀、鈣及鎂之含量較基部葉片多，不結果枝條磷、鉀之含量較多，而氮之含量除頂端葉片外，以結果枝較多。調查資料顯示，鈣對番石榴果實硬度，及成熟果之蒂腐病有關，因此夏威夷番石榴葉片之鈣標準含量定在1.25%以上。又土壤中可置換性鈉百分比增加，常常會造成營養之不均衡現象。 As the root system of guava is shallow, yield and fruit quality of guava are strongly influenced by fertilization management. Leaf analysis results indicated that increasing the P supply through foliar application would gradually increased the leaf P content, but had no effect on N and K contents. The seasonal variation study on the concentration of N, P, K and dry matter showed that for each constituent two peaks was observed, one before growth commencement and the other after growth cessation. The lowest concentrations was found after full fruit maturity. Therefore, superphosphate application is recommended when there is an apparent increase in yield. The N, P, and K contents of guava leaves decreased as the leaf age increased. Terminal leaves had more N, P, K, Ca and Mg than basal leaves. Non-fruiting branches had more P and K than fruiting ones. The preliminary data indicated that Ca was related to the firmness of fruits and blossom-end rot of mature fruits. In Hawaii, leaf calcium level of more than 1.25 % is standardized for preventing the above-mentioned problems. Hight exchangeable sodium percentage in soil usually causes nutrient imbalance in guava.