Source-sink relationships in tall fescue leaves. I.~Light intensity and photosynthesis. II.~Translocation of carbon-14-photosynthate

nderstanding leaf development is an important step towards the optimization of leaf production in forage species. In the present studies, the effect of light intensity during leaf development on tall fescue (Festuca arundinacea Schreb.) leaves is evaluated, and photosynthate partitioning along the elongating leaf blade is characterized.;Tall fescue plants were grown in the field at low light (30% of full sun) and in full sun. Leaves grown at low light were longer, had larger blade area, and lower specific leaf weight than leaves grown in full sun. Total stomatal density at low light was 20% less than at full sun with the larger reduction occurring on the abaxial epidermis. Leaves developed at 30% of full sun had carbon exchange rates per unit leaf area at irradiance saturation that were 20% lower when averaged over 2 years. However, internal CO;The youngest fully expanded leaf or the exposed tip of the elongating leaf blade of plants grown in continuous light (300...