First study on the reproductive biology of Justicia brasiliana Roth (Achantaceae) in the Brazilian Pampa

Abstract

The reproductive system of Justicia brasiliana Roth (Acanthaceae), a species from southern South America, so far remains unknown. We aimed to describe the reproductive biology of J. brasiliana as well as to assess the species pollen viability, stigma receptivity, fruit formation and seed viability. The study was conducted at the Irmão Teodoro Luis Botanic Garden in Capão do Leão municipality, Rio Grande do Sul state, southern Brazil. To analyze the species reproductive system, we established five treatments that tested for allogamy and autogamy, in addition to the control group. Pollen viability was determined by grain staining with 2% Carmine Acetic, whereas stigma receptivity was analyzed by hydrogen peroxide deposition on stigmatic papillae. Fruits were analyzed for the number of produced seeds, which themselves were subjected to a germination test to determine their viability. Data was analyzed in the statistical programs Bioestat and SPSS 20.0. J. brasiliana produced fruits at all autogamy and allogamy treatments, which thus enabled us to conclude that the analyzed species has a mixed reproduction system. All treatments yielded viable seeds, except for the control group. Neither pollen viability nor stigma receptivity differed significantly between the stages of flower bud and anthesis.