Modeling canopy transpiration and stomatal conductance of young apples using a parameterized Penman-Monteith equation

Kullaj, E.; Avdiu, V.; Lepaja, L.; Thomaj, F.; Kučera, Jiří

doi:10.17660/actahortic.2017.1177.58

Cited by 1 publication

(1 citation statement)

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“…There are two stages of the stomatal conductance reaction to the VPD changes. At the first stage, the conductance is close to the maximum at low or moderate VPD, but it shows a strong decrease after a certain threshold, which has been found in apple trees (Kullaj et al, 2017) and wheat (Schoppach et al, 2017). It is assumed that at low VPD, stomatal conductance is adjusted according to the feedback by the products of photosynthesis.…”

Section: Discussionmentioning

confidence: 90%

Impact of air drought on photosynthesis efficiency of the Siberian crabapple (Malus baccata L. Borkh.) in the forest-steppe zone of Transbaikalia, Russia

2019

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The adaption of photosynthesis, being a key metabolic process, plays an important role in plant resistance to air drought. In this study, the Siberian crabapple (Malus baccata L. Borkh.) in the forest-steppe zone of Transbaikalia region, Russia, was subjected to air drought stress and its photosynthesis characteristics were analyzed. The results show that air drought and sufficient soil moisture supply lead to the decrease in the total chlorophyll (Chl) content, while the ratio of Chls to carotenoids is constant in the Siberian crabapple tree. The function of photosystem II (PS-II) in the crabapple trees is characterized by a decrease in the fraction of absorbed light energy spent on the photochemical work and an increase in the proportion of non-photosynthetic thermal quenching. These changes indicate the photosynthetic down-regulation that acts as a universal photoprotective mechanism. During the midday hours, the combination of high air temperature and low air humidity leads to the decrease in the maximum photochemical quantum yield of photosystem II (F v /F m) and the efficiency of photosynthesis (P ABS). The parameters of leaf gas exchange show the significant differences in these values between the control and experimental variants. During the morning hours, the Siberian crabapple, growing in the Irkutsk City, assimilates carbon dioxide more intensively. Due to the higher air humidity, the stomata are kept open and the necessary amount of carbon dioxide entries the sites of carboxylation. The low air humidity combined with wind in the experimental variants leads to the unreasonably high water loss in the crabapple leaves by more than 27% as compared to the control variant (Irkutsk City). However, water use efficiency in the morning hours increases during plant photosynthetic processes, i.e., 42% higher than that of control. This, apparently, is a reflection of the adaptation processes of the Siberian crabapple to the air drought and parching wind.

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Section: Discussionmentioning

confidence: 90%