Intra-specific competition in maize: plant growth and kernel set of extreme plant hierarchies

PAGANO, E. AND MADDONNI, G.A

Seattle, Washington

Congreso; ASA, CSSA, SSSA Annual Meeting; 2004

ASA CSSA SSSA

The establishment of the intra-specific competition in maize results in the appearance of individuals with different skills in the raising of resources (dominant and dominated plants). This process begins well before the critical period for kernel set, but conditions kernel number per plant. We have analyzed plant biomass evolution, biomass partitioning to apical ear around silking, and kernel set of contrasting plant hierarchies of two maize hybrids previously characterized by their different tolerance to crowding (DK752, more and DK765, less tolerant). Hybrids were cropped at two stand densities (6 and 12 pl m-2) in rows 0.70m apart. For both hybrids, the largest difference in shoot biomass between plant types was detected at the nine ligulated-leaf stage and remained constant from this stage onwards. The less tolerant hybrid to crowding exhibited a significant trend to reduce biomass partitioning to ears in response to increased stand density, specially for dominated plants of the stand. Thus, extreme plant hierarchies of DK765 not only differed in plant growth rate around silking but also in ear growth rate, which was reflected in kernel set. These results give new evidences of the effect of early established plant hierarchies on kernel number determination, based on both plant growth rate around silking and assimilate partitioning to ears during this critical period.