Effects of drought on mesophyll conductance and photosynthetic limitations at different tree canopy layers

Abstract

In recent years, many studies have focused on the limiting role of mesophyll conductance (gm) to photosynthesis (An) under water stress, but no studies have examined the effect of drought on gm through the forest canopy. We investigated limitations to An on leaves at different heights in a mixed adult stand of sessile oak (Quercus petraea) and beech (Fagus sylvatica) trees during a moderately dry summer. Moderate drought decreased An of top and lowest beech canopy leaves much more than in leaves located in the mid canopy; whereas in oak, An of the lower canopy was decreased more than in sunlit leaves. The decrease of An was probably not due to leaf-level biochemistry given that VCmax was generally unaffected by drought. The reduction in An was instead associated with reduction in stomatal and mesophyll conductances. Drought-induced increases in stomatal limitations were largest in leaves from the top canopy, whereas drought-induced increases in mesophyll limitations were largest in leaves from the lowest canopy. Sensitivity analysis highlighted the need to decompose the canopy into different leaf layers and to incorporate the limitation imposed by gm when assessing the impact of drought on the gas exchange of tree canopies.

Seasonal variations in photosynthesis, intrinsic water-use efficiency and stable isotope composition of poplar leaves in a short-rotation plantation

“…This is in line with other studies (Wilson et al 2000 b , Grassi and Magnani 2005, Niinemets et al 2005, Limousin et al 2010, Flexas et al 2012). The relative contribution of stomatal vs mesophyll conductance to total limitations may however vary with species, with drought intensity and also with canopy position (Diaz-Espejo et al 2007, Galmes et al 2007, Cano et al 2013, Flexas et al 2013). This was confirmed in our study by the fact that g s reached higher values than g m by the end of the growing season.…”

Photosynthesis and photosynthetic efficiencies along the terrestrial plant’s phylogeny: lessons for improving crop photosynthesis

“…(2011), Han (), Jin et al (), Whitehead et al (), Xu and Zhou et al . (2011), Peguero‐Pina et al (, ,b), Tosens et al (,b, ), Varone et al (), Cano et al (), Martins et al (, ), Tomàs et al (, ), Battie‐Laclau et al (), Brito et al (), Hommel et al (), Théroux‐Rancourt et al (), Bazihina et al (), Benomar et al (), Cai et al (), Carriquí et al (, ,b), Kitao et al (), Lima‐Nieto et al (), Mizokami et al (), Shi et al (), Xiong et al (, , ), Dong et al (), Fini et al (), Huang et al (), Jaikumar et al (), Lu et al (), Medeiros et al (), Veromann‐Jürgenson et al (), Nadal et al () and Yang et al (). The two extreme lines of the boxplot ( whiskers ) show the 10 and 90% percentiles, the two boundaries of the box the 25 and 75% percentiles, and the centre thick line the median.…”

A molecular approach to drought‐induced reduction in leaf CO2 exchange in drought‐resistant Quercus ilex

“…As the drought severity increases, low chloroplastic CO 2 concentration triggers metabolic changes (e.g. restricted abundance or activity of chloroplastic enzymes and proteins) that further impair photosynthesis (Flexas and Medrano , Cano et al ). The respiratory metabolism is also affected by drought.…”