Caracterização biométrica de frutos, emergência e vigor de sementes de Cryptostegia madagascariensis bojer ex decne., espécie invasora no bioma caatinga

Abstract

Biological invasion is the process in which an organism exotic to adapt is competing with advantages with native species, causing serious impacts. Introduced in Brazil with landscaping purpose, Cryptostegia madagascariensis, has been revealed as invasive species. Populations arise naturally and spontaneously form massive autorregenerantes mainly in degraded areas and the banks of watercourses and temporary ponds. The research objective was to evaluate the biometric characteristics of fruits, emergence and vigor of C. madagascariensis, in order to understand the processes of occupation by this species. The experiments were performed at the Laboratory of Plant Ecology, Centre for Agrarian Sciences, Federal University of Paraiba. Essay I: fruits and seeds were collected and had their dimensions measured, accounting is still the number of seeds per fruit and fresh fruit and seeds; Essay II: effect of position and depth of sowing on the emergence and seedling vigor. Seeds were placed on the substrate with the heel down, up or to the side, at depths of 0.5, 1.0, 1.5, 2.0, 2.5 and 3.0 cm. It was found most frequently fruit with length ranging from 6.03 to 7.06 cm, width 2.43 to 2.86 cm and; thickness 1.70 to 2.13 cm. For most fruit (67%) gave 97-131 seeds, predominantly 6.90 to 7.50 mm in length, from 2.50 to 3.50 mm and width; 0.76 to 1.03 mm thick. The depth of 1.0 cm was responsible for 83% of seedlings emerged, independent of seed position. There was a reduction in the percentage of emergency, first count, speed of emergence, root length and dry weight of roots and shoots, with increasing depth. Thus we can conclude that the fruits have high seed production that associated with high rates of emergency and lack of natural enemies, this species provides significant advantages over native ace, constituting a serious threat to phytodiversity Caatinga and associated ecosystems.