Leaf and fruiting phenology and gas exchange of Mangabeira in response to irrigation

Abstract

The mangabeira (Hancornia speciosa Gómez) is a native species of Brazil occurring in the savanna (Cerrado) and Atlantic Coastal forests. It is a promising species for large-scale horticulture due to the high-protein properties of its fruits, but extensive cultivation has not yet been accomplished. Research is still needed to determine cultivation techniques that will optimize productivity. As irrigation is considered to be the most important agronomic technique to enhance productivity, the goal of this investigation was to evaluate the effects of irrigation on leaf gas exchange (net photosynthesis rate and transpiration rate) and foliar and fruiting phenology. Our results suggest that irrigation acts by increasing the growth and fruit production of mangabeira due to its effects on phenology. Gas exchange of adult plants was only marginally affected by irrigation; however, irrigated plants retained leaves longer than non-irrigated plants during the dry season, which increased the C gain over an annual period. The increase in C gain presumably led to irrigated plants having a higher relative frequency of fruited plants than the non-irrigated. A significant positive correlation between net photosynthesis rate per unit dry mass and specific leaf area was found for irrigated plants, which suggests that irrigation can promote the development of new leaf cells with no direct contribution to photosynthesis.