馴化光度對白馬粗肋草組織培養苗出瓶後葉片光合作用與植株生長之影響

Effects of Photosynthetic Photon Flux during ex vitro Acclimatization on Photosynthetic Behaviors and Growth of Micropropagated Aglaonema 'White Tip' Plantlets

白馬粗肋草組織培養苗出瓶置於25±1℃之育苗室，每日分別處理16小時之80、130或200μmol m^(-2)s^(-1)光度馴化70天，再經溫室栽培90天調查後期生長狀況，結果顯示出瓶後以130μmol m^(-2)s^(-1)處理者生長表現最佳。瓶內生長葉片之Fv／Fm值，在剛出瓶時為0.79，出瓶1天時下降至0.64，以80或130μmol m^(-2)s^(-1)處理者之測值皆在第2天時即回升，之後回復至正常範圍；但以200μmol m^(-2)s^(-1)處理者，瓶內形成之葉片在處理約第3週時與瓶外形成之葉片Fv／Fm值皆降至正常範圍值以下。以80μmol m^(-2)s^(-1)處理者，其瓶外形成葉片之光量子產量與瓶內外葉片之淨光合作用速率皆低於以130μmol m^(-2)s^(-1)處理者。以200μmol m^(-2)s^(-1)處理之瓶外新生葉片，其光量子產量與光化學淬熄係數皆較低，而最低螢光量較高。組培苗之蒸散速率和氣孔導度測值，在剛出瓶時皆很高，出瓶1天之測值即急速下降。在瓶內形成葉片的二氧化碳交換速率在剛出瓶時約為1.6μmol CO2 m^(-2)s^(-1)，於出瓶3天時較低，之後以80和130μmol m^(-2)s^(-1)處理者即呈現上升趨勢；但以200μmol m^(-2)s^(-1)處理者，在出瓶35天內交換速率持續下降。 Micropropagated Aglaonema 'White Tip' plantlets were transplanted to a soilless mix and placed in a growth room at 25±1℃ under coolwhite fluorescent light providing 16 h daily photosynthetic photon flux of 80, 130 or 200μmol m^(-2)s^(-1). After having been acclimatized for 70 days in the growth room, the plantlets were then transferred to a shaded greenhouse for 90 days and their growth was measured. Plantlets under 130μmol m^(-2)s^(-1) had subsequent greater growth. In all plantlets tested, the Fv/Fm value of in vitro formed leaves was measured as 0.79 at time of transferring out of flasks and then decreased to 0.64 on day 1. This Fv/Fm value increased to 0.75-0.85 in plantlets under 80 or 130μmol m^(-2)s^(-1)from day 2. In contrast, the Fv/Fm values were below 0.7 in both in vitro leaves and ex vitro leaves on day 21 in plantlets under 200μmol m^(-2)s^(-1).Plantlets under 80μmol m^(-2)s^(-1) had lower quantum yield of in vitro leaves and net photosynthesis of ex vitro leaves than plantlets under 130μmol m^(-2)s^(-1). Ex vitro formed leaves in plantlets under 200μmol m^(-2)s^(-1)had lowest quantum yield and qP, and highest F0 value. For all the plantlets tested, the stomatal conductance and transpiration rate values in the in vitro formed leaf were high at transfer and decreased dramatically on day 1 after transfer. Photosynthetic rate of the in vitro formed leaf was measured as 1.6μmol m^(-2)s^(-1)CO2 at transfer, decreased on day 3 and increased in plantlets under 80 or 130μmol m^(-2)s^(-1) within 40 days after transfer, but decreased gradually in those under 200μmol m^(-2)s^(-1)during the 35 days after transfer.