A Preliminary Experiment on the Effects of Leaf Wetting on Gas Exchange in Tomato Leaves

Canopy conductance and gas exchange of a Japanese cypress forest after rainfall‐induced wetness

“…Higher NEE during the first several hours after wetness ended in relationship with R n was only obvious in spring, Nevertheless, annual summed-up data showed that the average carbon uptake during the first several hours after wetness ended was larger than the usual dry time. These results are consistent with the increased stomatal conductance and photosynthesis right after wetness ended reported by previous studies (Hanba et al, 2004;Yokoyama et al, 2018). This study is based on ecosystem flux data from a Japanese cypress forest having rainfall as the only leaf wetness source, so further study concerning the leaf level patterns (e.g., stomata dynamic at different time after wetness ended) as well as leaf traits (e.g., stomatal density and distribution, leaf wettability) and precipitation and canopy wetting patterns will help to build a better understanding on the mechanism of the active gas exchange of the dry canopy after wet.…”

“…Increased gas exchange patterns have been observed for water-repellent species right after wetness ended or removed (Ishibashi & Terashima, 1995). For examples, Yokoyama et al (2018) measured gas exchange of misted tomato leaf right after the evaporation of misted water drop and found a higher photosynthesis rate from misted leaf especially at midday, which can be attributed to the compensation to the midday depression; Hanba et al (2004) detected the CO 2 assimilation rate and stomatal conductance after wetness pretreatment and revealed that the increasing assimilation rate of a nonwettable species (pea, Pisum sativum) can be explained by the increasing stomatal conductance, but the decreasing assimilation rate in a wettable species (bean, Phaseolus vulgaris) was resulted from both the reduced stomatal conductance and photosynthesis activity, which can explain the physiological mechanism for photosynthesis change relating to leaf wetness. However, to have a better understanding of the links between forest yield and global climate change as well as the relating models, awareness of how evapotranspiration and photosynthesis changes (either stimulation or depression) after wetness ended can be kept along with the recovering meteorological factors right after wetness ended is important.…”

Contribution of diffusional and non-diffusional limitations to the midday depression of photosynthesis which varies dynamically even under constant environmental conditions

“…Diffusional limitation refers to CO 2 uptake, which is determined in part by the conductivities of stomata, the path through the mesophyll cells inside the leaf, and the leaf surface boundary layer. A low conductivity of stomata (decrease in stomatal conductance) was often observed during the midday depression (Roessler and Monson, 1985;Raschke and Resemann, 1986;Yokoyama et al, 2018), and therefore it should be regarded as one of the main factors behind midday depression. The other contributing limitations (e.g., photoinhibition and sugar accumulation) are collectively referred to as non-diffusional limitations.…”