Maize kernel growth at different floret positions of the ear

The variation of individual kernel weight can have a large impact on final yield of maize (Zea mays L.). The goal of this research was to investigate the variation of maize kernel dry weight (KW) along the rachis of the ear and to determine the effect of kernel growth parameters on this variation. Field experiments were conducted for three years using two hybrids with contrasting plant densities. The fresh and dry weights of each kernel from one row of the ear were measured. Kernel growth at the basal, upper and apical sections of the ear was compared with that at the lower third section. The KW distribution in one row was the highest for the lower third section, followed by the basal and upper sections and the lowest for the apical section. The relative decrease in final KW of the other sections relative to the lower third section was determined by both the decrease in rate and duration of linear grain-filling for the normal density treatments, and was only determined by the decrease in growth rate for the low density treatments. The distribution of kernel water mass in one row showed the same trend as KW. However, the developments of kernel moisture content among sections were quite similar. The relative change in final KW of the other sections relative to the lower third section was closely correlated with the relative change in kernel maximum water mass (R2 = 0.99). This study reflects the substantial difference in KW along the rachis of the ear and indicates that the mechanism of individual kernel growth should be integrated into maize simulation models in order to predict yield more accurately.