Glutamine synthetase activity, relative water content and water potential in maize submitted to drought

Two maize (Zea mays L.) hybrids, BR 201 and P 6875, were submitted to drought by withholding irrigation at the vegetative or reproductive phases. During water deficit, in both phases, the relative water content (RWQ was higher and leaf water potential (Psi(w)) was lower in the hybrid P 6875 than in the hybrid BR201. This response indicated a better osmotic adjustment capacity of the hybrid P 6875 when compared to BR 201. Glutamine synthetase activity was not affected by drought even at a RWC of 60 % and Psi(w) of -1.2 MPa or during rehydration.