Germination of Jacaranda mimosifolia (D. Don - Bignoniaceae) seeds: effects of light, temperature and water stress.
The effects and interactions of temperature (10-40°C), light and water stress (-0.3, -0.6 or -0.9 MPa) on germination of J. mimosifolia seeds collected in Sao Paulo, Brazil, were studied. Germination percentage and rate were highest at 25°C, but differences between the 20, 25 and 30°C treatments were not significant. No seeds germinated at 10°C. White light slightly enhanced germination at temperatures ranging from 20 to 35°C (compared with seeds in the dark), indicating the possible role of phytochrome B in the control of seed germination in this species. Germination percentage and rate decreased as water stress increased from 0 to -0.9 MPa at all 3 temperatures tested (20, 25 and 30°C). Light increased percentage germination in seeds at -0.3 and -0.6 MPa at all temperatures, but had no effect at -0.9 MPa where germination was low or nil at all temperatures, with or without light.