Maize canopy production under contrasted water regimes

Two field experiments were employed to investigate canopy production in two cultivars of maize (Zea mays), Pioneer 34N43 and Pioneer 31H50, under contrasted water regimes. Plants were sampled at 1–3 day intervals to quantify extension of leaves and internodes. Final lengths of leaf laminae, sheaths and internodes were reduced when the organ extension was exposed to water stress; however, Pioneer 34N43 appeared to be more sensitive than Pioneer 31H50. An effective linear phase by simplifying a four-phase model was used to characterise organ extension in response to water stress. The coordination of the timing of sequential extension events of laminae, sheaths and internodes was preserved under mild water stress, but rates of processes were reduced. The rate of linear extension was principally responsible for reduction in organ length. This study provides robust relationships for use in modelling organ extension and canopy production under mild to moderate water stress.