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

Abstract

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 (R2 = 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).