Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp quốc tế đề tài:"Stomatal and non stomatal limitation of photosynthesis by leaf water deficits in three oak species: a comparison of gas exchange and chlorophyll a fluorescence data. | 435 Ann Sci For 1990 47 435-450 Elsevier INRA Original article Stomatai and non stomatai limitation of photosynthesis by leaf water deficits in three oak species a comparison of gas exchange and chlorophyll a fluorescence data D Epron E Dreyer INRA-Nancy Laboratoire deBioclimatologie et d BcophysiologieForestieres Station de Sylviculture et Production Champenoux F-54280 Seichamps France Received 5 April 1990 accepted 6 June 1990 Summary Net co2 assimilation A stomatai conductance for co2 g intercellular mole fraction of co2 Cl kinetics of chlorophyll a fluorescence and their half decay time t1 z their ratio of fluorescence decrease Rfd and their adaptive index Ap have been monitored on potted trees from 3 oak species Quercus petraea Qpubescens and Q ilex grown in a climate chamber and submitted to drought. Use of A vs Cl representations for photosynthesis data revealed an apparent impairment of mesophyll photosynthesis together with reduced CO2 supply to mesophyll due to stomatai closure. But in all species chlorophyll a fluorescence kinetics displayed very similar shapes constant f 2and stable Hạ and A values until predawn leaf water potential dropped MPa. These observations led to the conclusion that photochemical energy conversion and photosynthetic carbon reduction cycle could be very resistant to leaf water deficits and that observed decreases in mesophyll photosynthesis had to be attributed to a possible artefact in C calculation. On the other hand the susceptibility of leaves to photoinhibition increased as a consequence of water shortage especially in Qpetraea and Q pubescens Differences in drought adaptation between the studied species could probably be related to susceptibility to photoinhibition rather than to a direct sensitivity of photosynthesis to leaf water deficits at least in the range of stress Intensities of ecophysiologlcal significance. photosynthesis I water stress chlorophyll a fluorescence I oak stomatai conductance drought I .
