蝴蝶蘭涼溫催花前後之光需求

Light Requirement of Phalaenopsis during Prior to and Following Cool-Temperature Forcing

本研究以台灣原生蘭Phal. amabilis實生苗及大白花雜交種Phal. Joseph Hampton 'Diane'分生苗為材料，比較催花前營養生長期及其後抽梗和花序發育等生殖階段的光需求性，和影響開花品質的主要受光期。結果顯示蝴蝶蘭植株即使歷經4個月的高溫（35／30°C）及低光度等逆境，使葉面積及新葉的增長量不如30／25°C高光處理者，但此對其後續催花品質的影響卻不若涼溫催花期間光度強弱的影響大，所以涼溫催花期間的光度為影響蝴蝶蘭開花品質的關鍵受光期。Phal. amabilis植株以三種光度（250、50、25µmol•m-2•s-1）及光照期（12、6和2hrs）組合處理，其抽梗率及夜間淨CO2固定率，大致隨光強度之增強而提高，當夜間淨CO2固定率為負值者，抽梗率幾乎為零。整體而言，光積值高於1.1mol•m-2•day-1時抽梗率可達70%，至2.2mol•m-2•day-1時達100%，此後再提高光積值，抽梗率接近定值或反而下降。Phal. Joseph Hampton 'Diane'植株於抽梗前後以300、150、23µmol•m-2•s-1三種光度組合處理，顯示涼溫催花前期之光度會影響抽梗速率及花梗數，而抽梗後的光強度則為決定花朵數的關鍵期。

Comparison with light requirement of Phalaenopsis during various developmental stages on flower stalk emergence and flowering was examined in Phalaenopsis amabilis and Phal. Joseph Hampton 'Diane'. The reciprocal transfer experiments were used to investigate the time when (and if) the plants were sensitive to light intensity. Light intensity during cool-temperature forcing exert the paramount impact on the flower stalk emergence and flowering than those during vegetative stage prior to forcing. Furthermore, plants do not response to forcing temperature while under low photosynthetic photon flux or in darkness. Phal. amabilis forcing in 11 different light regimes (3 light duration - 12, 6, 2hrs - combined with 3 light intensity- 250, 50, 25µmol•m-2•s-1 ), it was shown that flower stalk emergence reached 70~100% as light integral increase up to 1.1-2.2mol•m-2•day-1 and thereafter remained approximately constant or decline. Due to low light intensity and short light duration, plants those failed to emerge flower stalks appeared negative dark CO2 fixation rate at 5 hours after dark period. Moreover, a 3 light levels (300, 150 and 23µmol•m-2•s-1) reciprocal transfer experiment at flower stalk visibility of Phal. Joseph Hampton 'Diane' indicated that floret number appeared to have a positive association with light intensity after flower stalk emergence.