tailieunhanh - Báo cáo khoa học: "A comparison of photosynthetic responses to water stress in seedlings from 3 oak species: Quercus petraea (Matt) Liebl, Q rubra L and Q cerris L"

Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp quốc tế đề tài: A comparison of photosynthetic responses to water stress in seedlings from 3 oak species: Quercus petraea (Matt) Liebl, Q rubra L and Q cerris L. | 48s Ann Sci For 1993 50 Suppl 1 48s-60s Elsevier INRA Original article A comparison of photosynthetic responses to water stress in seedlings from 3 oak species Quercus petraea Matt Liebl Q rubra L and Q cerris L D Epron E Dreyer G Aussenac Laboratoire de bioclimatologie et d ecophysiologie forestldres INRA Nancy Champenoux 54280 Seichamps France Summary Photosynthetic responses of oak seedlings Quercus petraea Q rubra and o cerris to drought were investigated using gas-exchange and chlorophyll fluorescence. Decreases in predawn leaf water potential Wp led to pronounced reductions in both stomatai conductance gw and net co2 assimilation rate A . In contrast the maximal photochemical efficiency of photosystem II PS II measured predawn Fj Fm remained unaffected until complete cessation of co2 assimilation. Responses of PS II photochemical efficiency AF Ftf to increasing photon flux density PFD were determined for leaves of both control and water-stressed seedlings. Drought resulted in a stronger reduction of 4F Fm. at a given PFD in o rubra and o petraea but not in Q cerris and led to an overreduction of the primary electron acceptor pool decrease in photochemical quenching q . Such behavior could explain the observed increase in sensitivity to photoinhibition when these 2 species were water-stressed. In contrast drought did not promote such an increase in the susceptibility of o cerris leaves to photoinhibition. chlorophyll fluorescence oak photosynthesis I drought photoinhibition Resume Comparaison de la réponse au deficit hydrique de la photosynthèse de semis de 3 espèces de chêne Quercus petraea Matt Liebl Q rubra L et Q cerris L. La réponse de la photosynthdse à la sdcheresse a été étudiée sur des semis de chêne Quercus petraea Q rubra et Q cerris par des mesures d echange gazeux et de fluorescence de la chlorophylle. La diminution du potentiel hydrique de base ywp a entraĩné une reduction importante de la conductance stomatique gw et de I assimilation nette de .