Assessing Specific Leaf Area of Maize Canopy Under Carbon Limitation.

Plant growth models often incorporate specific leaf area (SLA) or its reciprocal leaf mass per area (LMA) as a parameter to link leaf area expansion and carbon allocation. The two growth processes are coupled in that photosynthesis depends on the leaf area which thus determines the amount of carbon produced and allocated back to the leaf. Such a feedforward mechanism may remain on hold for some non-limiting conditions that might have provided a theoretical basis for linking two processes with a constant value of SLA, but the dynamics of SLA under various environmental conditions implying either source and/or sink limitation of carbon still need to be elucidated. In this study, we examined a comprehensive set of data collected from maize grown under multiple field conditions to better understand the dynamics of SLA. Three cultivars (Pioneer P32D79, P0636AMX, and P1690AM) were grown at two densities (30,000 and 79,000 plants per ha) and four nitrogen fertilization rates (0, 100, 200, and 300 kg per ha). Leaf area and dry mass of blade and sheath were measured for every individual leaf in the canopy.