Fig. 5.

Stomatal conductance (g_s) in relation to leaf-to-air vapour pressure deficit (Δ_w) in four clones of robusta coffee under irrigated conditions, measured over several days under naturally fluctuating Δ_w. Data were collected between 1100–1300 h in plants grown under full irrigation to ensure comparable internal water status (xylem pressure potential = −0·8 ± 0·2 MPa). For clone 109A the relationship between g_s and Δ_w was not significant.