Department of Botany, University of Illinois, Urbana, Illinois 61801.
Plant Physiol. 1971 Nov;48(5):532-6. doi: 10.1104/pp.48.5.532.
The inhibition of photosynthesis at low leaf water potentials was studied in soil-grown sunflower to determine the degree to which photosynthesis under high light was affected by stomatal and nonstomatal factors. Below leaf water potentials of -11 to -12 bars, rates of photosynthesis at high light intensities were insensitive to external concentrations of CO(2) between 200 and 400 microliters per liter. Photosynthesis also was largely insensitive to leaf temperature between 10 and 30 C. Changes in CO(2) concentration and temperature had negligible effect on leaf diffusive resistance. The lack of CO(2) and temperature response for both photosynthesis and leaf diffuse resistance indicates that rates of photosynthesis were not limited by either CO(2) diffusion or a photosynthetic enzyme. It was concluded that photosynthesis under high light was probably limited by reduced photochemical activity of the leaves at water potentials below -11 to -12 bars.
研究了土壤中生长的向日葵在低叶水势下光合作用的抑制作用，以确定高光下光合作用受气孔和非气孔因素影响的程度。在叶水势低于-11 至-12 巴的情况下，高光强下的光合作用速率对外部 CO(2)浓度在 200 至 400 微升/升之间不敏感。光合作用对 10 至 30°C 之间的叶片温度也基本不敏感。CO(2)浓度和温度的变化对叶片扩散阻力几乎没有影响。光合作用和叶片扩散阻力的 CO(2)和温度响应均缺乏表明光合作用的速率不受 CO(2)扩散或光合作用酶的限制。因此得出结论，在水势低于-11 至-12 巴的情况下，高光下的光合作用可能受到叶片光化学活性降低的限制。
