Coupling time to silking with plant growth rate in maize

In maize (Zea mays L.), progress towards pistillate flower maturity (silking) is highly dependent upon the environmental conditions around flowering. Under conditions that inhibit plant growth, female flower development is delayed relative to that of the male flowers resulting in an increase in the anthesis-silking interval (ASI). Although variation in ASI has been extensively documented, its relationship to plant growth is not well understood. Therefore, we developed a conceptual basis and experimental approach for quantifying and analyzing the process of female flowering in maize in response to variation in plant growth rate during the flowering period. Time to silking depends on biomass accumulation at the ear level, as silking for each plant is a developmental stage dependent upon ear expansion growth. Because plants within a maize canopy differ in their growth rate around flowering, plants with rapid growth rate reach silking earlier than the ones growing at lower rates. This is a consequence of differential accumulation of ear biomass around anthesis. As such, quantifying canopy plant-to-plant variability in ear growth around anthesis is a critical component for resolving time to silking for the population of plants. Moreover, plant biomass partitioning to the developing ear (ear growth rate/total plant growth rate around flowering) differs depending on the plant growth rate, and among genotypes. In order to resume this complexity, we developed a simple plant biomass growth framework to quantify time to silking for maize plant populations that takes into account plant-to-plant growth variability and partitioning of biomass to the developing ear around flowering. (C) 2007 Elsevier B.V All rights reserved.