Abstract
Rates of photosynthesis per unit of leaf area (P) differed among 10 varieties of sugarcane in a replicated field test. The variety ‘F. 36‐819’ was significantly higher in P than all others and the hybrids of Saccharum officinarum were lower than the interspecific hybrids. A correlation between P and leaf thickness (0.77) and between P and porosity (0.57) was found. Leaf thickness and porosity are more readily determined than P and may prove useful in the search for sugarcane varieties of higher photosynthetic potential. No correlation was found between P and stomatal number, stomatal length or leaf density thickness.