Plant-to-Plant Variability in Conventional and Transgenic Maize Hybrids.

Residual heterozygosis in parental lines of a single cross maize hybrid, or in lines of a transgenic hybrid, may determine plant-to-plant variability. The conventional DK747 maize hybrid and the transgenic versions of this hybrid (DK747MG, DK747RR, DK747MGRR) and the transgenic hybrids DK190MG, DK190RR, DK190MGRR were cultivated at two plant population densities (6 and 12 plants per square meter) without nutrients limitations and water restriction. Individual plant biomass and phonological stages were recorded along the cycle. From the six-leaf stage, plant population density effect on individual plant biomass was detected. Contrary, hybrid effect on individual plant biomass was detected from the three-leaf stage. At any stand population density, during the pre-silking and the period around silking period, plant growth rate of DK747 resulted lower than those of the transgenic versions. Similarly, the DK190RR and DK190MGRR exhibited higher plant growth rates than DK190MG. At the lowest plant population density, hybrid DK747RR exhibited a longer anthesis-silking interval (ASI), than those of DK747, DK747MG and DK747MGRR, but the ASIs of DK190MG, DK190RR and DK190MGRR were similar. At the highest stand density hybrids DK747, DK747MG and DK190MG exhibited the longest ASIs. Hence, plants of a similar genetic background exhibited differences among versions in both plant growth and plant development. Some of them were sustained at both plant population densities.