栽培溫度對綠竹光合作用及生物質量之影響

Differences in Photosynthetic Characteristics and Biomass of Green Bamboo (Bambusa Oldhamii) Grown under Different Temperatures

本研究以盆栽綠竹壓條苗為試驗材料，於臺灣大學人工氣候室15／13、20／15、25／20、30／25及35／30℃下栽培11個月，並以無溫控之塑膠棚簡易設施栽培為對照組。各組綠竹之葉片平均壽命介於66-101天，而與溫度的關係呈顯著負相關（R^2＝0.94，P＜0.05）。低溫組下（20／15℃、15／13℃）葉片壽命較對照組（21-26℃）長22-25天。於光強度1,200μmol．m^-2．s^-1與二氧化碳濃度350μmol．mol^-1下，綠竹葉片淨光合速率介於2.7-6.9μmol．m^-2．s^-1，且隨溫度上升而增高。淨光合速率與溫度之關係可以二次曲線迴歸模式表示（YPn＝－0.01X^2＋0.7128X－5.6692，R^2＝0.92，P＜0.01）；最大淨光合速率發生於溫度35.6℃。氣孔導度（0.09-0.22 H2O mol．m^-2．s^-1）與蒸散速率（2.0-2.8 H2O mmol．m^(-2)．s^-1）隨著溫度上升的趨勢與淨光合速率相同。兩個低溫處理組之每欉綠竹鮮重及乾重皆顯著低於其他各組，植株總鮮、乾重與溫度之關係亦呈顯著二次曲線迴歸模式。綠竹乾物重在各部位所佔比例依序為：枝桿＞根＞地下莖＞葉，各組相同。二低溫處理組落葉之比率較低，而有較高的根部比率。枝桿、地下莖與葉之乾物重所佔比例受溫度之影響較小。生產最大全株乾物重的溫度約在28.1℃。 The temperature effects on photosynthetic characteristics and biomass production of green bamboo (Bambusa oldhamii Munro) were studied. Mosaic virus-free potted green bamboo layers were grown for eleven months at phytotrons with day/night temperatures of 15/13, 20/15, 25/20, 30/25, and 35/30℃. Plants grown at a polyethylene tunnel with prevailing temperature were as control. The results showed that the life span of green bamboo leaves ranged in 66-101 days, and was negatively correlated with temperature (R^2＝ 0.94, P＜0.05). The leaf longevity under two lower temperature treatments was extended for 22-25 days comparing to the control. The net photosynthetic rate (Pn) of mature leaf was 2.7-6.93μmol．m^-2．s^-1, and increased with temperature up to 35/30℃ under light intensity of 1,200μmol．m^-2．s^-1 and 350μmol．mol^-1 CO2. A curvilinear regression model (Y(subscript Pn)＝－0.01X^2＋0.7128X－5.6692, R^2＝0.92, P＜0.01) depicted the relationship between Pn and temperature. The maximum Pn value would occur at 35.6℃. The stomatal conductance (0.09-0.22 H2O mol．m^-2．s^-1) and transpiration rate (2.0-2.8 H2O mmol．m^-2．s^-1) followed similar trend to temperature as Pn. Both fresh and dry biomass were lowest in plants under two lower temperature treatments. A curvilinear regression model depicted the relationship between biomass and temperature. The biomass partition in plant parts followed in decending order of branch and culm, root, rhizome and leaves. Lower biomass of leaf litter and higher biomass of root were obtained in green bamboo at both temperatures of 20/15℃and 15/13℃ comparing to higher temperature. The ratios partitioned in branch and culm, rhizome, and fresh leaves showed small variation. The maximum total dry weight of plant would attain at 28.1℃.