Effects of needle age, long-term temperature and CO2 treatments on the photosynthesis of Scots pine

Abstract

Naturally regenerated 20-25-year-old Scots pine (Pinus sylvestris L.) trees were grown in open-top chambers in the presence of an elevated temperature or CO(2) concentration, or both. The elevated temperature treatment was administered year-round for 3 years. The CO(2) treatment was applied between April 15 and September 15 for 2 years. The photosynthetic responses of 1- and 2-year-old needles to varying photon flux densities (0-1500 micro mol m(-2) s(-1)) and CO(2) concentrations (350, 700 and 1400 micro mol mol(-1)) during measurement were determined. The CO(2) treatment alone increased maximum photosynthetic rate and light-use efficiency, but decreased dark respiration rate, light compensation and light saturation regardless of needle age. In contrast, the temperature treatment decreased maximum photosynthetic rate and photosynthetic efficiency, but increased dark respiration rate, light compensation and light saturation. The aging of needles affected the photosynthetic performance of the shoots; values of all parameters except photosynthetic efficiency were less in 2- than in 1-year-old needles. The CO(2) treatment decreased and the temperature treatment enhanced the reduction in maximum photosynthesis due to needle aging.

Effects of soil warming and nitrogen fertilization on leaf physiology of Pinus tabulaeformis seedlings

“…It is also reported that most of the nitrogen is used for synthesizing components of the photosynthetic apparatus, and net assimilation rates increase linearly with leaf N concentration (Sugiharto et al 1990;Brown et al 1996). Consistent with the previous studies (Wang et al 1995;Chen et al 2005), warming and N fertilization significantly increased A max and U in P. tabulaeformis seedlings W experimental warming effect, F N fertilization effect, W 9 F the interactive effect of warming and N fertilization. NS not significant at the level of P = 0.05, significant at the level of *P = 0.05, significant at the level of **P = 0.01, significant at the level of ***P = 0.001 (Fig.…”

“…6; Zhao and Liu 2009). Soil warming generally increased the value of light compensation point (LCP) in literature (Wang et al 1995). Similarly, our results also implied that warming was favorable for improving LCP of P. tabulaeformis.…”

“…Warming was reported to increase the activity or the amount of Rubisco, and provide more optimal temperature conditions for photosynthesis (Wang et al 1995). It is also reported that most of the nitrogen is used for synthesizing components of the photosynthetic apparatus, and net assimilation rates increase linearly with leaf N concentration (Sugiharto et al 1990;Brown et al 1996).…”

Short-term responses of Picea asperata seedlings of different ages grown in two contrasting forest ecosystems to experimental warming

“…In this study, elevated temperatures significantly enhanced A, A max and R d . This was possibly because that warming provided more optimal temperature conditions for gas exchange (Wang et al, 1995). Moreover, in the present case, artificial warming significantly increased the leaf N concentrations for two age classes regardless of experimental sites.…”

Growth, physiological and biochemical responses of Meliaceae species - Azadirachta indica and Melia dubia to elevated CO2 concentrations

“…[12] and in seedlings of loblolly pine there was an increase in the optimum temperature for Anet in trees grown under elevated CO 2 . Contrarily, mature Pinus sylvestris (L.) [13] and Betula papyrifera, Picea mariana and Populus tremuloides [14] observed a decrease in Anet with an increase in temperature under both ambient and elevated CO 2 suggesting that there was no interactive effects of temperature by CO 2 treatment interaction. The present study was taken up to investigate the biochemical responses of two tropical tree species of family Meliaceae to elevated CO 2 .…”