Mesophyll conductance to CO2 in relation to drought in hybrid poplar

The study examines the physiological response of two hybrid poplar clones to two soil moisture: control (80% field capacity) and drought (40 % field capacity). Four weeks after treatments, we measured the photosynthetic CO2 response curve and estimated mesophyll conductance, Vcmax and Jmax. Amax, gse,  gm et Vcmax decreased under drought. The ratio gm to gs increased under drought conditions.