Short-term water stress impacts on stomatal, mesophyll and biochemical limitations to photosynthesis differ consistently among tree species from contrasting climates

Abstract

Predicting the large-scale consequences of drought in contrasting environments requires that we understand how drought effects differ among species originating from those environments. A previous meta-analysis of published experiments suggested that the effects of drought on both stomatal and non-stomatal limitations to photosynthesis may vary consistently among species from different hydroclimates. Here, we explicitly tested this hypothesis with two short-term water stress experiments on congeneric mesic and xeric species. One experiment was run in Australia using Eucalyptus species and the second was run in Spain using Quercus species as well as two more mesic species. In each experiment, plants were grown under moist conditions in a glasshouse, then deprived of water, and gas exchange was monitored. The stomatal response was analysed with a recently developed stomatal model, whose single parameter g1 represents the slope of the relationship between stomatal conductance and photosynthesis. The non-stomatal response was partitioned into effects on mesophyll conductance (gm), the maximum Rubisco activity (Vcmax) and the maximum electron transport rate (Jmax). We found consistency among the drought responses of g1, gm, Vcmax and Jmax, suggesting that drought imposes limitations on Rubisco activity and RuBP regeneration capacity concurrently with declines in stomatal and mesophyll conductance. Within each experiment, the more xeric species showed relatively high g1 under moist conditions, low drought sensitivity of g1, gm, Vcmax and Jmax, and more negative values of the critical pre-dawn water potential at which Vcmax declines most steeply, compared with the more mesic species. These results indicate adaptive interspecific differences in drought responses that allow xeric tree species to continue transpiration and photosynthesis for longer during periods without rain.

ORCHIDEE-MICT (v8.4.1), a land surface model for the high latitudes: model description and validation

“…Instead, a stress factor, which ranges from 0 to 1, is calculated based on the relative moisture content at each soil layer. This factor is applied to stomatal conductance and mesophyll conductance, as well as the maximum RuBisCO activity rate (Vcmax) and maximum electron transport rate (Jmax), in order to account for experimentally observed effects of drought on stomatal and non-stomatal photosynthetic limitation (Zhou et al, 2014). The stress factor (γ ) of water limitation is calculated as…”

A test of an optimal stomatal conductance scheme within the CABLE land surface model

“…Bonan et al (2014) showed that during drought periods, the formulation of the soil moisture stress scalar was likely to be the cause of error in g s calculations, rather than the g s scheme itself. Zhou et al (2013Zhou et al ( , 2014 demonstrated that the g 1 parameter could be linked to a more theoretical approach to limit gas exchange during water-limited periods, by considering differences in species water use strategies.…”

Algunos aspectos de la fotosíntesis y potenciales hídricos de la granadilla (Passiflora ligularis Juss.) en estado reproductivo en el Huila, Colombia

“…Entre los parámetros fisiológicos más importantes para evaluar la respuesta fisiológica de la planta, se encuentran los de intercambio gaseoso como fotosíntesis y transpiración, fuertemente controlados por factores ambientales como la luz y la temperatura que pueden reducir la asimilación de CO 2 , disminuir la producción de carbohidratos o incluso ocasionar un daño irreversible sobre el aparato fotosintético (Zhou et al, 2014;Stasik y Jones, 2007). La fluorescencia de la clorofila que brinda información sobre el estado del fotosistema II y de la presencia de algún estrés biótico o abiótico en la planta (Baker, 2008;Maxwell y Johnson, 2000), y el potencial hídri-co, además de determinar el estado hídrico de la planta, se identifican los puntos más críticos a lo largo del día y en prealba (Zhou et al, 2014;Eamus et al, 2006).…”

“…La fluorescencia de la clorofila que brinda información sobre el estado del fotosistema II y de la presencia de algún estrés biótico o abiótico en la planta (Baker, 2008;Maxwell y Johnson, 2000), y el potencial hídri-co, además de determinar el estado hídrico de la planta, se identifican los puntos más críticos a lo largo del día y en prealba (Zhou et al, 2014;Eamus et al, 2006).…”