Pirênios e plântulas de três espécies de malpighiaceae de uma savana amazônica: aspectos morfológicos e tecnológicos

Abstract

Byrsonima crassifolia (L.) Kunth, Byrsonima coccolobifolia Kunth and Byrsonima verbascifolia (L.) DC. of the family Malpighiaceae stand out as one of the commonest in the group of savannas vegetation of the “Rio Branco-Rupununie” landscape complex. The “Rio Branco-Rupununie” landscape complex lies in the state of Roraima and is one of the largest blocks of savannas in South America and in the largest area of savannas in Brazilian Amazonia. Morphological and technological studies of the reproductive organs of the native species of savannas area of Brazilian Amazonia are unknown. In Malpighiaceae, despite the unassailable economic and medicinal importance of the species of the genus Byrsonima the studies as to these aspects are few. So, it was intended to investigate morphological aspects of the pyrenes and seedling of B. crassifolia (L.) Kunth, B. coccolobifolia Kunth and B. verbascifolia (L.) DC. of an Amazonian savannas of Boa Vista, Roraima, as well as technological aspects of the pyrenes of three species of Byrsonima. For this purpose, weekly collections between the months of April to July of 2012 were conducted for the obtaining of the pyrenes coming from ripe fruits collected from 12 individuals of natural populations of an area of savannas, in the Água Boa Campo Experimental, of Embrapa Roraima, municipality of Boa Vista-RR. The pyrenes of the three species studied are similar, but, B. crassifolia presented pyrenes with greater diameter while B. coccolobifolia greater length and weight and B. verbascifolia lower weight and seeds with greater length, breadth and thickness in relation to the other two species investigated. The seedlings of the three species present distinct morphological pattern, B. crassifolia have phanerocotyledonary, epigeous and foliaceous seedlings, whereas B. coccolobifolia and B. verbascifolia present phanerocotyledonary, hypogeous and foliaceous seedlings. Other traits ranged among the species, the subsequent epicotyl and the internodes on seedlings of B. verbascifolia are reduced while the development of the plumule is lateral in relation to the cotyledons of B. coccolobifolia. The species B. coccolobifolia and B. verbascifolia present cryptogeal germination, underground plumule, cotyledonary node below soil level and fusion of the cotyledonary petioles as a way of keeping themselves protected from fire which is recurrent on areas of savannas. Pyrenes of B. crassifolia, B. verbascifolia and B. coccolobifolia present physiological dormancy and the method with immersed pyrenes in gibberellic acid solution at a concentration of 500 mg L-1 for 48 hours and integers was more efficient in overcoming seed dormancy of the three species of Byrsonima.