Fig. 2. Relationships between grain weight and (A) rate of grain filling, and (B) duration of grain filling, for nine sunflower hybrids grown in October (S1) and December (S2) sowing dates at Venado Tuerto during 1996-1997 and 1998-1999. For genotype groups (i.e., G1, G2, G3) see legend of Fig. 1.