Clifford Gerwick B, Williams George J
Department of Botany, Washington State University, 99164, Pullman, WA, USA.
Program in General Biology, Washington State University, 99164, Pullman, WA, USA.
Oecologia. 1978 Jan;35(2):149-159. doi: 10.1007/BF00344728.
Opuntia polyacantha was collected from the shortgrass prairie in Colorado. Carbon dioxide and water vapor exchange was monitored in plants pretreated and analyzed under cool temperatures (20/15°C) and warm temperatures (35/15°C). Well watered plants under a 35/15 thermoperiod supported the fixation of atmospheric CO during the night, early morning, and late afternoon. Plants under a 20/15 thermoperiod exhibited CO uptake only during the afternoon. The fixation of CO at night could be stimulated or induced by decreasing the night temperature. Plants from which water was withheld two or four weeks showed a decline in CO fixation with the uptake at night exhibiting the greatest sensitivity. Under conditions of water stress the enhancement of CO uptake at night by cool night temperatures was largely lost. Plants water stressed for 4 weeks recovered rapidly upon rewatering under warm or cool temperatures. Rates of CO fixation were comparable to well watered plants within 24 h. The effects of temperature and water stress on gas exchange are compared to the in situ growth pattern of O. polyacantha and contrasted with the regulation of gas exchange observed in C and C grasses of the shortgrass prairie.
多刺仙人掌采自科罗拉多州的矮草草原。在低温（20/15°C）和高温（35/15°C）条件下，对预处理和分析过的植株进行二氧化碳和水汽交换监测。在35/15温度周期下充分浇水的植株，在夜间、清晨和傍晚能够固定大气中的二氧化碳。在20/15温度周期下的植株仅在下午吸收二氧化碳。降低夜间温度可刺激或诱导夜间二氧化碳的固定。停水两周或四周的植株，其二氧化碳固定量下降，夜间吸收量表现出最大敏感性。在水分胁迫条件下，夜间低温增强的二氧化碳吸收量大部分丧失。水分胁迫4周的植株在温暖或凉爽温度下重新浇水后迅速恢复。24小时内二氧化碳固定速率与充分浇水的植株相当。将温度和水分胁迫对气体交换的影响与多刺仙人掌的原位生长模式进行比较，并与矮草草原C3和C4禾本科植物中观察到的气体交换调节进行对比。
