Densidade estomática de duas espécies florestais: Ademanthera Pavonina L. e Hevea Brasiliensis Muel Arg.

Abstract

The Amazon concentrates the largest diversity of forest species on the planet, among which are Adenhantera pavonina L. and Hevea brasiliensis Muell Arg. Considering the scarcity of studies relating stomata to the physiology of these species in the literature, the objective of the present work was to analyze the stomatal density and its relationship with the physiology of the species. The leaf was chosen because it is part of the plant that has the largest number of stomata in a plant. The botanical material was collected in two green areas of Itacoatiara-AM, the “Horto Florestal”, where leaves of A. pavonina were collected and the “Bosque das Seringueiras”, where the leaves of H. brasiliensis were collected. For each species were collected leaves of the apex, middle and base, and three samples for each tree position of three different individuals, the leaves were conserved in alcohol 70% for further analysis. For the determination of the stomatal density, the epidermis was dissociated with sodium hypochlorite, safranin stained and later mounted on the slides for analysis under an optical microscope. The location and types of stomata were confirmed by freehand paradermic cuts. Both species have hypoestomatic leaves, presenting homeostomatic leaves (only one type of stoma). H. brasilienis has paracitic stomata. In frontal view, epidermal cells have irregular shape and size with sinuous walls presenting greater sinuosity on the adaxial face. The species showed significant difference in stomatal density for different tree positions (186.3 stomata / mm² at the apex, 153.5 stomata / mm² in the middle and 129.3 stomata / mm² at the base). A. pavonina has sinuous-walled cells and smooth-walled cells of irregular size and shape on the adaxial face and irregularly sized sinus cells on the abaxial face. This species has unicellular tectoral trichomes and can be observed throughout the leaf blade. A. pavonina showed no significant difference for different tree positions. (67.4 stomata / mm² at the apex, 69.1 stomata / mm² in the middle and 67.9 stomata / mm² at the base).