Desempenho germinativo da invasora Leucaena leucocephala (Lam.) de Wit. e comparação com Caesalpinia ferrea Mart. ex Tul. e Caesalpinia pulcherrima (L.) Sw. (Fabaceae)

Abstract

Success in establishing and colonizing new areas is directly related to germination behaviour of seeds under local environmental conditions. This work aimed to compare germination performance of the exotic invader Leucaena leucocephala to two legumes (Caesalpinia ferrea, native, and C. pulcherrima, exotic) which are not considered invasive. Non-scarified seeds were exposed to constant temperatures of 15, 20, 25, 30, 35 and 40 oC, within a photoperiod of 12 hours, for 100 days. Both final germination percentage and germination speed showed significant differences among the three species. C. ferrea had low germination percentage, with optimal germination temperature at 25 oC, reaching germination percentage of 59% and germination speed of 0.68 seeds d -1. In contrast, C. pulcherrima had high germination percentages at all temperatures tested, with highest germinability from 20 to 40 oC. Seeds of L. leucocephala had the lowest germination percentage and optimal germination temperature was 35 oC. The germination performance of this exotic is not outstanding, and factors such as propagule pressure, natural scarification and good performance in other life stages must contribute to its invasiveness.