銨態與硝酸態氮比例影響大白花蝴蝶蘭營養與生殖生長

Ammonium-to Nitrate-Nitrogen Ratio Affects Vegetative and Reproductive Growth in Phalaenopsis Sogo Yukidian 'V3'

為瞭解蝴蝶蘭於營養及生殖生長階段適宜之銨態及硝酸態氮施用比例，本研究以大白花蝴蝶蘭（Phalaenopsis Sogo Yukidian 'V3'）之中苗與大苗為材料，施用五種不同氮型態比例之肥料（NH4-N:NO3-N=0:100; 25:75; 50:50; 75:25; 100:0）。總氮濃度皆為15mM，試驗進行20個月。結果於兩個開花週期中，不同型態之氮肥比例對蝴蝶蘭大苗至抽梗與至開花所需天數無顯著影響。然而於第二開花週期時，持續施用銨態氮比例超過50%之處理，會降低植株之抽梗率、總花朵數、花梗直徑及長度。對於營養生長，蝴蝶蘭大苗及中苗之鮮重、葉片數及葉面積會隨著銨態氮比例的增加而減少。當肥料中銨態氮比例超過50%時，根部對於陽離子的吸收受到抑制，使得蝴蝶蘭植體中鈣、鎂濃度下降，並造成植株生長遲滯、葉片黃化及根部壞死等銨毒害現象。因此建議使用NH4-N與NO3-N比例為25:75之肥料，可使蝴蝶蘭有最高之抽梗率、鮮重及葉片數。 In order to understand the proper ammonium: nitrate fertilizer ratio for desirable vegetative and reproductive growth of Phalaenopsis Sogo Yukidian 'V3', five fertilizers varied in nitrogen form ratio (NH4-N: NO3-N=0:100, 25:75, 50:50, 75:25, 100:0) were applied at the same concentration (15 mM) for 20 months. Two independent experiments were carried out using young plants (20 cm in leaf span) and mature plants (32 cm in leaf span), respectively. The days to spiking and days to anthesis of the mature plants were not affected by ammonium to nitrate ratio differences during the observation in two flowering cycles. However, the spiking percentage, the number of flowers, and the diameter and length of stalk in the second flowering cycle decreased when plant received more than 50% NH4-N. The fresh weight, leaf number and leaf area of both young and mature plants decreased with increased NH4-N. When supplied with 50% or higher NH4-N, the absorption of cations by Phalaenopsis roots was inhibited; and, hence, the concentrations of calcium and magnesium in the plants decreased, while symptoms of ammonium toxicity such as growth retardation, chlorosis leaves, and necrotic roots, occurred. We therefore recommend to apply nitrogen fertilizers containing 75% nitrate and 25% ammonium nitrogen in ratio to Phalaenopsis in order to achieve the highest percentage of spiking, fresh weight, and leaf numbers.