Dynamics of the Elongation of Internodes in Maize (Zea mays L.). Effects of Shade Treatment on Elongation Patterns

The dynamics of elongation of individual maize internodes havepreviously been characterized under standard agronomic conditions.In this paper these dynamics are compared with those under ashading treatment. Shading was applied after the tip appearanceof leaf 6, using a black net that transmitted 20% of light,without altering spectral composition. Internode length wasdetermined as a function of thermal time by measuring the verticaldisplacement of individual leaf collars. Shading slowed plantdevelopment and caused significant reductions in internode length.The onset of the linear phase of elongation was delayed by shading,but its duration was not affected. The reduction in the linearelongation rate was almost totally responsible for the reductionin the final length of phytomers in the shade treatment. Theco-ordination between collar emergence and the onset of linearelongation remained. These results support the contention thatthe kinetics of internode elongation are controlled by the emergenceof leaf collars. Copyright 2000 Annals of Botany Company Zea mays L., internode, elongation, dynamics, model, shade, light, phytomer, stem, thermal time, photomorphogenesis