株齡影響蝴蝶蘭對介質鹽度的耐受度

Developmental Age of Phalaenopsis Affects its Tolerance to Substrate Salinity

蝴蝶蘭（Phalaenopsis spp.）為著生植物，其根部對高鹽環境敏感，然而不同生育階段植株可耐受之鹽度卻少有研究。鹽度為溶液中鹽類離子之總合，相同鹽度下，鹽類離子的組成差異亦可能影響蝴蝶蘭生長及養分吸收。本研究以氯化鈉調配不同EC值之液態肥料，栽培大白花蝴蝶蘭小苗（6cm盆）、中苗（8.5cm盆）及大苗（10.5cm盆），液態肥料EC值之增加致使介質EC值上升，造成鹽類逆境，抑制蝴蝶蘭植株生長與大苗抽梗率。各苗期能耐受之液態肥料EC值各異，小苗低於1.15 dS．m^(-1)，中苗低於2.15 dS．M^(-1)，而大苗低於3.15 dS．M^(-1)；若欲維持大苗之抽梗表現，EC值應低於2.15 dS．m^(-1)。肥液之鹽度明顯影響蝴蝶蘭根部之生長，隨著鹽度增加，地下部乾重隨之下降；反之，以逆滲透水處理者，根部乾重最高。另以不同濃度肥料及氯化鈉調配不同EC值的肥液種植大白花蝴蝶蘭，離子吸收之拮抗作用隨澆灌液肥之EC值增加益趨明顯：施用EC值高於2.15 dS．m^(-1)之液肥，限制蝴蝶蘭對鈣離子及鎂離子的吸收；而相同EC值之養液，鈉離子濃度提高，會強化拮抗作用，使蝴蝶蘭對鉀離子、鈣離子及鎂離子的吸收更為困難。 The roots of Phalaenopsis spp., which are naturally epiphytic orchids, are sensitive to high salinity. Little work has been done to investigate the salinity tolerance of the plants during various growth stages. Even under similar salinity, different ionic composition may affect the growth and nutrient absorption of Phalaenopsis plants. Phalaenopsis Sogo Yukidian 'V3' plants grown in 6-cm pots, 8.5-cm pots, and 10.5-cm pots were treated with fertilizer solutions with different salinities, which were achieved by adding various amounts of NaCl to a base nutrient solution containing a 15N-2.2P-12.5K fertilizer at 150 mg．L^(-1) N. Under salinity stress, the growth and spiking percentage of Phalaenopsis plants are adversely affected. Phalaenopsis plants in different growth stages have different tolerance levels to fertilizer solution salinity. The upper limit of fertilizer solution salinity for young plants in 6-cm pots is 1.15 dS．M^(-1) whereas for medium-sized plants in 8.5-cm pots it should be lower than 2.15 dS．M^(-1). The fertilizer solution salinity for Phalaenopsis mature plants grown in 10.5-cm pots should be lower than 3.15 dS．M^(-1); however, the EC value should be lower than 2.15 dS．M^(-1) for acceptable spiking rate. Roots of Phalaenopsis were sensitive to high medium EC, its dry weight decreased as the salinity increased; plants treated with water resulted in greatest root growth. When Phalaenopsis plants were fertilized with nutrient solutions having different ionic composition and salinity, antagonism between ions became more pronounced with increasing fertilizer solution salinity. Fertigation with salinity higher than 2.15 dS．m-1 reduced the absorption of calcium and magnesium by Phalaenopsis plants. Under similar EC values, raising the concentration of sodium in fertilizer solutions intensified the antagonism between ions, making it more difficult for the plants to absorb potassium, calcium, and magnesium.