Phenological effects on photosynthesis : suggestion for modeling

Results are presented about the effects of fruiting and flowering on leaf nitrogen content and photosynthetic capacity in mango. The relationship between leaf photosynthetic capacity and the total amount of nitrogen per unit leaf area, Na, seems to be a robust one in mango, but the presence of inflorescences changes the origin and slope of the linear relationship between mitochondrial respiration rate and Na. The presence of developing fruits has a positive effect on Na of leaves experiencing the same light regime than control leaves. This effect was found to be mediated mainly by an increase in the mass-to-area ratio of leaves, Ma. On the contrary, the leaf-to-fruit ratio per se has a negative effect on Na by decreasing the leaf nitrogen concentration per unit mass, while Ma remains constant. The possibility of incorporating such effects in a biochemical model of leaf photosynthesis is discussed.