A biochemical model of photosynthesis for mango leaves: evidence for the effect of fruit on photosynthetic capacity of nearby leaves

摘要

Variations in leaf nitrogen concentration per unit mass (N-m)and per unit area (N-a), mass-to-area ratio (M-a) total nonstructural carbohydrates (T-a), and photosynthetic capacity (maximum carboxylation rate, electron transport capacity, rate of phosphate release in triose phosphate utilization and dark respiration rate) were studied within the digitized crowns of two 3-year-old mango trees (Mangifera indica L.) on La Reunion Island. Additional measurements of N-m, N-a, M-a, T-a and photosynthetic capacities were performed on young, fully expanded leaves of 11-year-old mango trees. Leaves of similar gap fractions were taken far from and close to developing fruits. Unlike N-m, both N-a, and T-a were linearly correlated to gap fraction. Similar relationships were found for all leaves whatever their age and origin, except for T-a, for which we found a significant tree effect. Photosynthetic capacity was non-linearly correlated to N-a, and a unique relationship was obtained for all types of leaves. Photosynthetic acclimation to light was mainly driven by changes in Ma, but allocation of total leaf N between the different photosynthetic functions also played a substantial role in acclimation to the lowest irradiances. Leaves close to developing fruits exhibited a higher photosynthetic capacity than other leaves, but similar T-a. Our data suggest that T-a does not control photosynthetic capacity in mango leaves. We used the data to parameterize a biochemically based model of photosynthesis and an empirical stomatal conductance model, allowing accurate predictions of net photosynthesis of leaves in field-grown mango trees.