Physiological differences in yield related traits between flint and dent Argentinean commercial maize genotypes

Grain yield, KNP, KW, plant growth rate and biomass partitioning around flowering, kernel set efficiency per unit of accumulated ear biomass at flowering and assimilate availability per kernel during flowering all showed significant kernel type (flints vs. dents) effects (p < 0.05). And significant genotype differences within each kernel type were evident for all traits (p < 0.01). Flint kernel type showed lower yields (ca. 80% of dents) due to reduced KNP and KW. This lower KNP in flints was mostly related to a lower plant growth rate around flowering, although they also showed a reduced biomass partitioning to the ear during this period. Flint genotypes, however, showed higher kernel set efficiency per unit of accumulated ear biomass when compared to dents (p < 0.01). Lower KW in flints was related to a reduced assimilate availability per kernel around flowering (p < 0.01), both kernel types showed similar assimilate availability per kernel during grain filling (p > 0.05). This indicated flint and dent kernel types had the same amount of assimilates to fulfill their early established potential KW. Our results emphasize the importance of the flowering period for understanding yield differences between flints and dents, and biomass accumulation rate during this period was identified as a key trait for increasing flint yields.