Pollen Source and Post‐Flowering Source/Sink Ratio Effects on Maize Kernel Weight and Oil concentration

Previous studies have documented pollen effect on maize ( Zea mays L.) kernel oil concentration and the stability of this trait for a wide range of post‐flowering source/sink ratios. Few efforts, however, have been devoted to establishing the functional relations among pollen source, source/sink ratio, and kernel oil concentration. Kernels of a normal oil content hybrid (DK752) self‐pollinated and those of the same hybrid but pollinated with a high oil pollinator genotype (5MG) were sampled during the grain‐filling period to evaluate the effect of different post‐flowering source/sink ratios on kernel and embryo growth dynamics and oil deposition in the embryos. Final weight of kernels and embryos were related to post‐flowering source/sink ratio, but embryo oil concentration was not modified. Pollen source affected both embryo weight (∼31 and 41 mg for DK752×DK752 and DK752×5MG, respectively) and embryo oil concentration (∼330 and 380 g kg −1 for DK752×DK752 and DK752×5MG, respectively). Final weight of kernels and embryos were closely related to variations in their growth rates (R 2 = 0.79–0.82). The robust relationship between embryo growth rate and kernel growth rate determined the steady embryo/kernel ratio (∼12.6 and 16.1% for DK752×DK752 and DK752×5MG, respectively) and kernel oil concentration of each cross (∼68 and 93 g kg −1 for DK752×DK752 and DK752×5MG, respectively).