Fig. 6. Relationship between seasonal water deficit and grain yield of soybean, maize, sunflower, and wheat grown in commercial fields. Lines are fitted regressions. Correlation coefficients are shown for the linear regressions between yield and water deficit before (Pre), during (CP), and after (Post) the most critical period for yield determination and for the seasonal water deficit (Season). The most critical periods were defined as follows: Pod and grain set for soybean, i.e., between stages R3 and R5 (Calviño and Sadras, 1999); 40 d bracketing silking in maize (Tollenaar and Dwyer, 1999); 60 d bracketing anthesis in sunflower (Cantagallo et al., 1997); and 30 d before anthesis in wheat (Fischer, 1985). Significance levels are *, 0.05; **, 0.01; and ***, 0.001
