Photosynthetic temperature responses of Eucalyptus globulus and Eucalyptus nitens

Abstract

Steady-state photosynthetic responses to leaf temperature of 4-year-old Eucalyptus globulus Labill. and E. nitens (Deane and Maiden) Maiden trees were measured between 10 and 35 degrees C at approximately monthly intervals from early spring to midwinter. The photosynthetic temperature optimum of recently expanded leaves in the sun canopy was linearly related to the average temperature of the preceding week during the 9-month measurement period. The optimum temperature for net photosynthesis of E. globulus increased from 17 to 23 degrees C as the mean daily temperature increased from 7 to 16 degrees C. Similarly, the optimum temperature for net photosynthesis of E. nitens increased from 14 to 20 degrees C as the mean daily temperature increased from 7 to 19 degrees C. The temperature for maximum photosynthetic response of E. globulus and E. nitens was similar at each measurement time, but the photosynthetic performance of E. nitens was less sensitive to temperatures above and below this optimum than that of E. globulus. In December, the apical shoots of branches of E. globulus had a net photosynthetic temperature optimum of between 10 and 15 degrees C. The corresponding values for expanding leaves, fully expanded leaves from the current year's growth, and fully expanded leaves from the previous year's growth were 15, 20 and 20-25 degrees C, respectively. In a second experiment, E. globulus clones taken from four mother plants originating from climatically dissimilar locations within Tasmania were acclimated at day/night temperatures of 10/15, 18/23 and 25/30 degrees C in temperature-controlled greenhouses. Another set of clones was acclimated in a shadehouse where temperatures ranged between 10 and 25 degrees C and with a mean daily temperature of approximately 15 degrees C. Plants grown at 25/30 degrees C had significantly lower net photosynthetic rates when measured at 10 and 20 degrees C than plants grown at lower temperatures. Plants grown at 10/15 degrees C had significantly lower net photosynthetic rates when measured at 30 degrees C than plants grown at higher temperatures. Plants grown at the ambient conditions prevailing in midautumn in Hobart had significantly higher net photosynthetic rates at 20 degrees C than plants raised in the greenhouses and were equal best performers at 10 and 30 degrees C. A comparison of the light response curves of the plants showed that the maximum rate of net photosynthesis was affected by the growth temperature, whereas the apparent quantum efficiency remained unchanged. There were no significant differences in the photosynthetic temperature responses of the four genotypes derived from climatically dissimilar locations within Tasmania. A comparison of temperature response models for E. globulus indicated that incomplete acclimation (defined by a slope value of less than 1 for the linear relationship between the temperature optimum for photosynthesis and the growth temperature) generally resulted in a greater daily carbon uptake than complete acclimation (slope value of 1).

Modelling temperature acclimation effects on the carbon dynamics of forest ecosystems in the conterminous United States

“…Similar slopes were observed or reported in Oxyria digyna (Billings et al, 1971), in Ledum groenlandicum (Smith and Hadley, 1974), in Eucalyptus globulus and E. nitens (Battaglia et al, 1996). Berry and Bjo¨rkman summarised that plants exhibit considerable differences in their photosynthetic response to temperature and reflect an adaptation to the temperature regimes of their native environments (Berry and Bjorkman, 1980).…”

Leaf-Level Gas Exchange and Foliar Chemistry of Common Old-Field Species Responding to Warming and Precipitation Treatments

“…Previous studies investigating how leaf-level gas exchange rates respond to changes in temperature have found both increases and decreases in plant photosynthetic rates and net primary productivity (NPP; Battaglia et al 1996;Rustad et al 2001;Nemani et al 2003;Welker et al 2004;Ciais et al 2005;Wu et al 2011). Even slight warming may cause some plant species to exceed their metabolic optima, reducing photosynthetic output and decreasing plant survival (Niu et al 2006;Sage et al 2008).…”

Different growth and physiological responses to experimental warming of two dominant plant species Elymus nutans and Potentilla anserina in an alpine meadow of the eastern Tibetan Plateau

“…Thus, prediction of ecosystem responses to climatic warming in a future world strongly relies on our understanding of plant physiological acclimation (Zhou et al 2007). Acclimation of physiological processes has been reported in the literature when plants were exposed to changed temperatures (Edward and Smith 1988, Battaglia et al 1996, Loik et al 2004, Xiong et al 2000, Bolstad et al 2003, Lee et al 2005, Yamori et al 2005. Among physiological parameters, light-saturated photosynthetic rate, apparent quantum yield of the photochemical efficiency of photosystem II and activities of antioxidant enzymes are temperature-dependent and the most sensitive parameters in response to global warming (Atkin et al 2005, Xiong et al 2000, Jarvis et al 2004, Xin and Browse 2000.…”