Leaf-area based CO2 assimilation rate (ALA as an Indicator of genotypic differences in photosynthetic capacity is questioned on the basis of correlations found between ALA and specific leaf weight and small leaf size. To address this question of photosynthetic apparatus concentration In F. chiloensis genotypes differing significantly in ALA, visual image analysis software was used to quantify a number of leaf anatomy parameters. In 1991 and 1992, after gas exchange measurements in the field, leaf tissue was prepared In cross-sections and leaf clearings for light microscopy. Cross-sections were used to measure internal anatomical parameters and clearings for vein and stomatal densities.
Analysis of variance of 1991\92 measurements showed significant genotypic variation for leaf veination, leaf thickness, palisade cell length, cross-sectional area In mesophyll tissue and internal air space. Differences in stomatal density were observed in 1991. None of the anatomical parameters measured were correlated with ALA. This suggests that the concentration of physical apparatus Is not the major source of variation In ALA among these eight genotypes.