Caird Mairgareth A, Richards James H, Hsiao Theodore C
Department of Land, Air, and Water Resources, University of California, One Shields Avenue, Davis, CA 95616-8627, USA.
Funct Plant Biol. 2007 Apr;34(3):172-177. doi: 10.1071/FP06264.
Incomplete stomatal closure at night can result in substantial water loss at times when photosynthetic carbon gain is not occurring in C and C plant species. To investigate the magnitude of nighttime water loss for a crop species in the field, measurements of nighttime water loss by tomato (Lycopersicon esculentum Mill. cv. Heinz 8892) were made by three methods: a field-scale lysimeter and two leaf-level instruments, an automated viscous flow porometer and a portable photosynthesis system. The portable photosynthesis system indicated nighttime transpiration of 10% of maximal daytime transpiration and the viscous flow porometer demonstrated partially open stomata. Integrated crop water loss during the dark, non-photosynthetic hours measured on the lysimeter was 3-10.8% of total daily water loss. In the glasshouse, a survey of closely related wild and cultivated tomato species showed that under ambient conditions nighttime transpiration varied within and among species and was 8-33% of maximal daytime transpiration. Implications of such a substantial fraction of total daily crop water use occurring during the night are significant in agronomic, environmental, and economic terms. Further, variation within and among species in nighttime water loss has implications for breeding to improve crop water use efficiency.
在C₃和C₄植物物种中，夜间气孔不完全关闭会导致在不进行光合碳固定时大量失水。为了研究田间作物物种夜间的失水量，采用三种方法对番茄（Lycopersicon esculentum Mill. cv. Heinz 8892）的夜间失水量进行了测量：一种田间规模的蒸渗仪和两种叶片水平的仪器，即自动粘性流气孔计和便携式光合作用系统。便携式光合作用系统显示夜间蒸腾量为白天最大蒸腾量的10%，粘性流气孔计显示气孔部分开放。在蒸渗仪上测得的黑暗、非光合时段作物的累计失水量占每日总失水量的3 - 10.8%。在温室中，对亲缘关系密切的野生和栽培番茄物种进行的一项调查表明，在环境条件下，夜间蒸腾量在物种内部和物种之间存在差异，为白天最大蒸腾量的8 - 33%。夜间失水量占作物每日总用水量的很大一部分，这在农艺、环境和经济方面都具有重要意义。此外，物种内部和物种之间夜间失水量的差异对提高作物水分利用效率的育种工作也具有重要意义。
