Temperature and light requirements for germination of species of Velloziaceae from different Brazilian rocky outcrops

Abstract

Germination is the fi rst step to successful plant establishment. Th e range of factors that promote germination varies among species. Light and temperature requirements for the germination of species of Velloziaceae were investigated. Seeds of Barbacenia fl ava, B. markgrafi i, B. purpurea, B. williamsi, Vellozia alata, V. compacta, V. glochidea and V. plicata were collected from rocky outcrops located in diff erent Brazilian states and were incubated for germination at 10 to 40 °C in light or dark conditions. Seed mass and length were measured for each species. In general, all species exhibited a high germination percentage at temperatures of 15-40 °C in the light, with the optimal temperature being 25-30 °C for species of Barbacenia and 30 °C for species of Vellozia. Barbacenia fl ava, V. compacta and, particularly, B. markgrafi i, germinated in the dark. In contrast, B. purpurea exhibited an absolute requirement for light and the most restricted range of temperature to germinate. Germination responses and seed traits were related to the microclimate where the species were collected, and germinability in darkness is likely a common trait for species of Velloziaceae from the Espinhaço Range.Keywords: Barbacenia, darkness, granitic outcrops, inselbergs, ironstone outcrops, optimal temperature, quarzitic outcrops, Vellozia Acta Botanica Brasilica -32(2): 240-246. April-June 2018.