Homeostasis of respiration under drought and its important consequences for foliar carbon balance in a drier climate: insights from two contrasting Acacia species

Abstract

Under drought, when photosynthesis (A) is impaired, foliar respiration (R) becomes crucial to estimate plant carbon balance. However, the effects of drought on R remain unclear and little is known about differences between congeners with divergent anatomy. In this study we compared the physiological response to imposed drought in plants of two Acacia species: Acacia pycnantha Benth. and Acacia floribunda (Vent.) Willd. in a controlled environment. We subjected half of the plants to two desiccation cycles. Relative water content (RWC), the ratio of variable to maximum fluorescence (F v /F m ), phyllode dark respiration (R dark ), stomatal conductance to water (g s ), light-saturated photosynthesis (A sat ) were monitored. Drought significantly reduced RWC, g s , F v /F m , and A sast ; increased the instantaneous water use efficiency in the species with higher foliage mass per area (FMA) (A. pycnantha) and did not have any significant effect on R dark but increased the R dark /A sat ratio. Although the shape of the response to drought of both species was similar, the two species differed in the magnitude in the increase of the R dark /A sat ratio, with drought-mediated increases in R dark /A sat being greater in A. floribunda than in A. pycnantha; the latter also showing greater recovery of photosynthesis. Collectively, our results highlight the extent to which drought alters the carbon balance of the two selected species. The homeostasis of R dark under drought is particularly relevant within a climate change scenario where more severe and frequent drought episodes are predicted to occur.

Implications of leaf-scale physiology for whole tree transpiration under seasonal flooding and drought in central Cambodia

“…(Huang et al, 2008;Novriyanti et al, 2012;Whitehead and Beadle, 2004) and Acacia spp. (Gimeno et al, 2010;Han et al, 2010;Pryor et al, 2006) have V cmax25 similar to the species in this study. The high V cmax25 reflects the successional status of the species measured in this study: eucalyptus and acacia were planted here as fast growing species (Forestry Administration of Cambodia, personal communication) and Tbeng and Popel successfully survive in this study site under frequent disturbance by human activities and wild fires, through resprouting from the stumps.…”

Mitochondrial Alternative Oxidase Maintains Respiration and Preserves Photosynthetic Capacity during Moderate Drought in Nicotiana tabacum

“…There is less consensus in the literature of how drought impacts respiration rate (Atkin and Macherel, 2009). In some cases, drought was reported to have little or no effect on respiration rate (Ribas-Carbo et al, 2005;Giraud et al, 2008;Gimeno et al, 2010), whereas other studies reported decreases (Haupt-Herting et al, 2001;Haupt-Herting and Fock, 2002;Taylor et al, 2005;Vassileva et al, 2009;Galle et al, 2010;Ayub et al, 2011) or even increases (Bartoli et al, 2005;Feng et al, 2008;Hummel et al, 2010;Begcy et al, 2011). We found that both R D and R L tended to be lower (by about 27%) in moderate drought-stressed than well-watered wild-type N. tabacum (Fig.…”

Characterizing the drivers of seedling leaf gas exchange responses to warming and altered precipitation: indirect and direct effects

“…Alternatively, other studies have found no effect of soil moisture changes on respiration (Galmes et al . 2007; Gimeno et al . 2010).…”