Research advances in nighttime transpiration and its eco-hydrological implications

It is generally assumed that transpiration does not occur at night because leaf stomata are opened during the day and closed at night. Nonetheless, there is increasing evidence that the stomata are opening in many species and in a range of habitats at night. Nighttime transpiration rates are typically 5%—15% of daytime rates. This proportion of nighttime transpiration is often highest (30%—60%) in arid desert systems. Control of nighttime transpiration may have considerable complexity, it relates to the different levels control variables. The magnitude of nighttime transpiration with plant genetic factors, it is also affected by abiotic factors, such as vapor pressure difference, wind speed, soil moisture, atmospheric CO₂ concentration, soil temperature and so on. Study shows that water vapor pressure deficit is the most important environmental driving factors to nighttime transpiration. Nighttime transpiration has significant implications for water budgets as an inevitable process. It can reduce leaf water potential of plant, contribute to imbalance between predawn leaf water potential and soil water potential, reduce hydraulic redistribution, affect of ecological water balance, enhance nutrient availability, and affect the productivity and growth of plant.