TAILIEUCHUNG - Báo cáo khoa học: "Temperature response of photosynthesis of silver fir (Abies alba Mill.) seedlings."

Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp quốc tế đề tài: Temperature response of photosynthesis of silver fir (Abies alba Mill.) seedlings. | Ann. For. Sci. 59 2002 163-170 INRA EDP Sciences 2002 DOI forest 2002003 163 Original article Temperature response of photosynthesis of silver fir Abies alba Mill. seedlings Piotr Robakowskia Pierre Montpiedb and Erwin Dreyerb University of Agriculture in Poznan Department of Forestry ul. Wojska Polskiego 69 60-625 Poznan Poland b Unité Mixte de Recherches INRA-UHP Écologie et Écophysiologie Forestieres 54280 Champenoux France Received 26 March 2001 accepted 12 November 2001 Abstract - Temperature responses of photosynthesis were assessed in a shade tolerant tree species silver fir Abies alba Mill. using leaf gas exchange and chlorophyll a fluorescence measurements. Four-year-old seedlings grown in a greenhouse in N-E France were transferred into a climate chamber and kept during 24 hours at six temperature levels 10 18 26 32 36 and 40 oC. Response curves of net CO2 assimilation to substomatal CO2 partial pressure were obtained on small twigs bearing a single row of needles under saturating irradiance. Maximal carboxylation rate Ucmax and maximal light driven electron flow Jmax were estimated by fitting Farquhar s model to the response curves at each temperature. Dark respiration Rd was estimated at the end of each response curve by measuring gas exchange after 5 min darkness in the chamber. The temperature responses of the three parameters were fitted to a thermodynamic model. Mean values at a reference temperature of 25 oC were 37 91 and qmolm-2 s-1 for Lcmax JmaxandRd respectively. Optimal temperature was higher for Lcmax oC than for Jmax oC and no optimum was detected for Rd. Such values are very close to those of broadleaved tree species. The Jmax Vcmax ratio decreased with temperature. Activation energies were estimated at 56 50 and 23 kJ mol-1 for Vcmax Jmax and Rd respectively. The maximal quantum efficiency of PS II estimated from chlorophyll a fluorescence declined significantly above 36 oC. It nevertheless fully recovered after 1 .

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