Morphological analysis of leaf growth of maize: responses to temperature and light intensity

Existing models of leaf-area expansion of Gramineae species are empirical and species-specific. To increase understanding of the mechanisms involved in leaf-area expansion, effects of environmental factors on leaf growth of the non-tillering species maize (Zea mays L.) were analysed quantitatively. A growth chamber experiment was carried out with the cultivar Luna including different combinations of temperature (day/night temperatures 13/8, 18/13, 23/18 and 28/23 degreesC) and photosynthetic-photon-flux density (PPFD) (104, 185 and 277 mu mol m(-2) s(-1)). At 13/8 degreesC, a large proportion of the plants died due to prolonged exposure to cold stress. Both high temperatures and high PPFDs increased leaf-appearance rate. Maximum leaf width was highest at intermediate temperatures and high PPFDs, and was strongly related to specific-leaf weight (R-adj(2) = 0.88). Leaf-elongation rate increased and leaf-elongation duration decreased with temperature, the resultant being a maximum final leaf length at 23/18 degreesC. Leaf length decreased slightly with PPFD, caused by a shorter leaf-elongation duration. Leaf shape has been described with a new function and was different for Leaves 1 and 2 than for higher-positioned leaves. Leaf width was closely associated with specific leaf weight. The observed relationships can be used in dynamic simulation of leaf area based on plant morphology.