Ku S B, Edwards G E, Tanner C B
Departments of Horticulture and Soil Science, University of Wisconsin, Madison, Wisconsin 53706.
Plant Physiol. 1977 May;59(5):868-72. doi: 10.1104/pp.59.5.868.
Individual leaves of potato (Solanum tuberosum L. W729R), a C(3) plant, were subjected to various irradiances (400-700 nm), CO(2) levels, and temperatures in a controlled-environment chamber. As irradiance increased, stomatal and mesophyll resistance exerted a strong and some-what paralleled regulation of photosynthesis as both showed a similar decrease reaching a minimum at about 85 neinsteins.cm(-2).sec(-1) (about (1/2) of full sunlight). Also, there was a proportional hyperbolic increase in transpiration and photosynthesis with increasing irradiance up to 85 neinsteins.cm(-2).sec(-1). These results contrast with many C(3) plants that have a near full opening of stomata at much less light than is required for saturation of photosynthesis.Inhibition of photosynthesis by 21% O(2) was nearly overcome by a 2-fold increase in atmospheric levels of CO(2) (about 1,200 ng.cm(-3)). Photosynthesis at 25 C, high irradiance, 2.5% O(2) and atmospheric levels of CO(2) was about 80% of the CO(2)-saturated rate, suggesting that CO(2) can be rate-limiting even without O(2) inhibition of photosynthesis. With increasing CO(2) concentration, mesophyll resistance decreased slightly while stomatal resistance increased markedly above 550 ng.cm(-3) which resulted in a significant reduction in transpiration.Although potato is a very productive C(3) crop, there is substantial O(2) inhibition of photosynthesis. The level of O(2) inhibition was maximum around 25 C but the percentage inhibition of photosynthesis by O(2) increased steadily from 38% at 16 C to 56% at 36 C. Photosynthesis and transpiration showed broad temperature optima (16-25 C). At higher temperatures, both the increased percentage inhibition of photosynthesis by O(2) and the increased stomatal resistance limit photosynthesis, while increased stomatal resistance limits transpiration. Water use efficiency, when considered at a constant vapor pressure gradient, increased with increasing irradiance, CO(2) concentration, and temperature.
将马铃薯（茄属马铃薯L. W729R）这种C3植物的单叶置于可控环境舱中，使其受到不同的辐照度（400 - 700纳米）、二氧化碳水平和温度的影响。随着辐照度增加，气孔阻力和叶肉阻力对光合作用产生了强烈且在一定程度上平行的调节作用，因为二者都呈现出类似的下降趋势，在约85爱因斯坦·厘米-2·秒-1（约为全日照的1/2）时达到最小值。此外，随着辐照度增加至85爱因斯坦·厘米-2·秒-1，蒸腾作用和光合作用呈比例双曲线式增加。这些结果与许多C3植物形成对比，那些植物在远低于光合作用饱和所需光照强度时气孔就几乎完全张开。21%的氧气对光合作用的抑制作用几乎被大气中二氧化碳水平增加两倍（约1200纳克·厘米-3）所克服。在25℃、高辐照度、2.5%氧气和大气二氧化碳水平条件下的光合作用约为二氧化碳饱和速率的80%，这表明即使没有氧气对光合作用的抑制，二氧化碳也可能成为限制速率的因素。随着二氧化碳浓度增加，叶肉阻力略有下降，而当二氧化碳浓度高于550纳克·厘米-3时气孔阻力显著增加，这导致蒸腾作用大幅降低。尽管马铃薯是一种高产的C3作物，但存在明显的氧气对光合作用的抑制。氧气抑制水平在25℃左右达到最大值，但氧气对光合作用的抑制百分比从16℃时的38%稳步增加至36℃时的56%。光合作用和蒸腾作用表现出较宽的温度适宜范围（16 - 25℃）。在较高温度下，氧气对光合作用抑制百分比的增加以及气孔阻力的增加都限制了光合作用，而气孔阻力的增加则限制了蒸腾作用。在恒定蒸汽压梯度下考虑时，水分利用效率随着辐照度、二氧化碳浓度和温度的增加而提高。
