Interactive effects of elevated CO2 and drought stress on leaf water potential and growth in Caragana intermedia

Abstract

We studied the responses of leaf water potential ( w ), morphology, biomass accumulation and allocation, and canopy productivity index (CPI) to the combined effects of elevated CO 2 and drought stress in Caragana intermedia seedlings. Seedlings were grown at two CO 2 concentrations (350 and 700 µmol mol −1 ) interacted with three water regimes (60-70%, 45-55%, and 30-40% of field capacity of soil). Elevated CO 2 significantly increased w , decreased specific leaf area (SLA) and leaf area ratio (LAR) of drought-stressed seedlings, and increased tree height, basal diameter, shoot biomass, root biomass as well as total biomass under the all the three water regimes. Growth responses to elevated CO 2 were greater in wellwatered seedlings than in drought-stressed seedlings. CPI was significantly increased by elevated CO 2 , and the increase in CPI became stronger as the level of drought stress increased. There were significant interactions between elevated CO 2 and drought stress on leaf water potential, basal diameter, leaf area, and biomass accumulation. Our results suggest that elevated CO 2 may enhance drought avoidance and improved water relations, thus weakening the effect of drought stress on growth of C. intermedia seedings.

Photosynthesis acclimation, leaf nitrogen concentration, and growth of four tree species over 3 years in response to elevated carbon dioxide and nitrogen treatment in subtropical China

“…Relatively low photosynthesis rate in the leaves of S. superba grown with the low N treatment and elevated CO 2 concentration in the later measurement period also supported the finding. During our measurement, O. pinnata growth was not affected by the CO 2 concentration treatments, which is contrary with most of previous studies where tree growth was positively affected by elevated CO 2 concentration (Xiao et al 2005;Ceulemans et al 1996;Sefcik et al 2007). However, we hypothesized that the greater growth would soon be found for the O. pinnata grown with the elevated CO 2 concentration as downregulation of photosynthesis was not found for this species.…”

The impact of climate change on the growth of tropical agroforestry tree seedlings

“…Markesteijn and Poorter (2009) suggested that an increase in S/R may occur to maximize growth under stress conditions. A significant increase in RMF in the TEMPx f CO 2 and TEMP treatments compared to ambient conditions was also reported by Xiao et al (2005) and Raizada et al (2009). For example, Raizada et al (2009) found a greater RMF when Caragana intermedia Kuang and H.C. Fu was exposed to 700 ppm, and suggested that this may indicate insufficient nutrient availability.…”

“…An increase in the S/R ratio for both tree species in the TEMP, f CO 2 and TEMPx f CO 2 treatments compared to AMB conditions was also reported in other studies (Wilson 1988;Shenglei and Ferris 2006;Xiao et al 2005;Overdieck et al 2007;Allen and Vu 2008). Markesteijn and Poorter (2009) suggested that an increase in S/R may occur to maximize growth under stress conditions.…”

“…A decrease in LAR in both G. sepium and C. odorata, was also reported by others (Hui et al 2002;Xiao et al 2005;Raizada et al 2009;Körner 2009), and may be due to an increased productivity on a smaller photosynthetic area (Xiao et al 2005). As such, f CO 2 and TEMPx f CO 2 may be more efficient photosynthetically compared to seedlings grown under AMB conditions.…”

“…Values followed by the same lowercase letter, comparing between treatments, for each G. sepium or C. odorata for C, N or C/N ratio are not significantly different at P[0.05 and temperate environments reported a positive effect on tree seedling growth parameters under CO 2 fertilization relative to current ambient conditions (Wurth et al 1998;Raizada et al 2009;Xiao et al 2005;Lindroth 2010). For example, Sigurdsson et al (2001) found a 45% increase in Populus trichocarpa Torr.…”