氮肥濃度對百香果生長發育之影響與葉片礦物元素含量之週年變化

Effects of Different Nitrogen Dosages on the Growth and Development on Passion Fruits and Seasonal Changes of Mineral Elements in Leaves.

以百香果臺農雜交1號盆栽試驗探討氮肥濃度（5、10、15、20mM）對其生長發育之影響；並於臺東之果園進行取樣分析，調查其葉片主要元素含量之週年變化。氮肥濃度以15mM處理較佳，無論地上部、根生長勢與元素含量均較5、10mM處理組為優。20mM處理雖地上部生長較佳，但根生長受阻且磷、鉀、鈣等元素吸收較少，且氮素在組織中累積，可能已呈氮素過量的現象。不同節位的葉片，由頂部往基部，氮及磷含量漸降，而鈣和鎂則漸升，鉀含量以葉片接近展開的時期為最高。分析要素含量週年變化顯示，氮、磷、鉀含量在11月達全年最高峰後漸降，至4月有一低峰出現，在生長期中受到開花著果與生長週期改變而起伏，鈣的全年變化幅度不大，鎂則較不規則。此等變化受植株生長發育、氣候因子及果園管理之影響。

The effects of nitrate concentrations (5, 10, 15, 20mM) on growth of potted passionfruit were studied. The seasonal changes of mineral elements in leaves grown in orchards at Taitung were also analysed. Application of 15mM nitrogen resulted in a more vigorous growth thn that of 5 or 10mM. Nitrogen with 20mM retarded root growth and the absorption of P, K and Ca, and meanwhile, nitrate was accumulated in the tissues. It appeared that 20mM nitrogen is excessive for the growth of passionfruit. As passionfruit leaves increased in age, the N and P contents decreased and Ca and Mg increased. K content attained maximum when leaf almost fully expended. The analysis of seasonal changes of macroelements in leaves showed that N, P and K contents reached their maximum in November and minimum in April. Only small difference for Ca content and no definite trend for Mg content were founded.