Effect of expansion time and sunlight radiation on the functional and anatomical traits of mango tree leaves

Abstract

The mango tree (Mangifera indica L.) is cultivated on a large scale in Brazil for economic purposes. Since the leaves, as the main photosynthetic organs, play an essential role in fruit production, the primary objective of the present study was to analyze comparatively the morphological
characteristics of leaves at different stages of expansion and of leaves exposed to different levels of solar radiation. Leaves were collected at the beginning of expansion, during intermediate expansion and when completely expanded, and sun and shade leaves were compared. The individuals were adult plants without flowers and fruits located along the South Lake, Brasília. The leaves were analyzed for area, specific leaf area (SLA), thickness, water content and anatomical traits. Data were analyzed by ANOVA post hoc Tukey test to test the influence of leaf expansion time and by the T-test to determine the effect of radiation (α = 5%). Greater scleromorphy was observed in the completely expanded leaves compared to the leaves at the beginning of expansion, with lower water content and SLA in completely expanded leaves. Higher sclerophyll content was observed in sun leaves than in shade leaves, with lower SLA, greater leaf thickness and greater thickness of adaxial epidermis, palisade parenchyma and mesophyll in sun leaves. Based on these results, greater care is indicated regarding leaf management at the beginning of expansion and the management of shade leaves, since they are
more susceptible to damage from herbivores. The objective of this management is to maximize fruit production.