Growth of Individual Leaves of Spring Wheat (Triticum aestivumL.) as Influenced by Temperature and Light Intensity

Abstract

Existing models of leaf area expansion of Gramineae species based on individual leaf growth are descriptive and assume that there is no effect of tiller type on individual leaf area. However, sound experimental data on the growth of individual leaves on a plant are lacking. A growth chamber experiment was carried out with young spring wheat (Triticum aestivumL.) plants, and individual leaf area parameters were measured. Treatments were temperature (daily mean 10.5, 15.5 and 20.5 °C) and light intensity (111, 191 and 286 μmol m-2s-1). Effects of leaf position and tiller type on maximum leaf width and leaf elongation rate (LER) could be explained by a new assumption, that maximum leaf width, and LER, of a leaf depend on the values for the previous foliar leaf on the same tiller, or on the parent tiller. LER increased linearly with temperature and was not affected by light intensity, whereas maximum leaf width was not influenced by temperature or light intensity. Leaf elongation duration was closely related to phyllochron expressed in days, although this relation was slightly modified by light intensity. Equations formulated for each leaf area parameter accounted for 90% of the variation in leaf area between different leaf types, temperatures and light intensities. The results give a better general understanding of individual leaf growth of Gramineae species and can be used in the development of more mechanistic models for the simulation of leaf area expansion.