Donor side parameter (W
) and reaction center parameter (RC
) of PSII in leaves of grape plants sprayed with H
O ( filled circles ) and SA ( open circles ) under normal growth temperature (NT, 25°C), and treated with H
O ( filled triangles ) and SA ( open triangles ) under heat stress (HT, 43°C) and recovery. Each value is the mean ± SE of 4 replicates. Treatment conditions are described in Fig. 1. At the same time point, numerical values with different letters are significantly different (P < 0.05).