[Specific density of leaf as a characteristic of the photosynthetic apparatus].

At early stages of ontogeny (up to 50-60% of the maximum leaf area) of wheat (Triticum aestivum L.), meadow fescue (Festuca pratensis Huds.), reed fescue (F. arindinacea Schreb.), and sugar beet (Beta vulgaris L. var. saccharifera (Alef) Krass), there is correlation between changes in the specific leaf density (SLD), rate of photosynthetic CO2 assimilation; activity of the key photosynthetic enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco, EC 4.1.1.39); and concentration of chlorophyll (Chl) a, Chl b, carotenoids, and soluble leaf proteins. However, there is no correlation of SLD with the activity of phospho(enol)pyruvate carboxylase (EC 4.1.1.31). Senescence of leaves was accompanied by a decrease in the SLD value. Treatment with cytokininomimetics (6-benzylaminopurine and Metribuzin) caused an increase in the SLD value. The specific leaf density is suggested to be a structural and functional characteristic of the photosynthetic apparatus of agricultural plants.