Responses of ribulose-1,5-bisphosphate carboxylase, protein content, and stomatal conductance to water deficit in maize, tomato, and bean

We compared responses of maize, tomato, and bean plants to water stress. Maize reached a severe water deficit (leaf water potential -1.90 MPa) in a longer period of time as compared with tomato and bean plants. Maize stomatal conductance (g(s)) decreased at mild water deficit. g(s) of tomato and bean decreased gradually and did not reach values as low as in maize. The protein content was maintained in maize and decreased at low water potential (Psi (w)); in tomato it fluctuated and also decreased at low Psi (w); in bean it gradually decreased. Ribulose-1,5-bisphosphate carboxylase/oxygenase activity remained high at mild and moderate stress in maize and tomato plants; in bean it remained high only at mild stress.