EFFECT OF TEMPERATURE AND LIGHT ON SEED GERMINATION AND SEEDLING GROWTH OF Swietenia macrophylla King

The significant economic potential of Swietenia macrophylla has caused immense reductions in the native populations, jeopardizing their survival. Restoring these populations requires the establishment of quality seedling production, which depends on adequate evaluation of the physiological state of seeds. Thus, the aim of this study was to evaluate the effect of temperature and light on seed germination and seedling growth of S. macrophylla. The experimental design was completely randomized, with ten treatments of four replicates of 50 seeds. Treatments consisted of: constant temperatures of 23, 29, 35 and 41 degrees C, with photoperiods of 24 and 12 h of light, and alternating temperatures of 25-35 degrees C and 30-40 degrees C, with 12 h of light. Water content, germination, germination speed index, stem diameter, root length, shoot length, root dry mass and shoot dry mass of seedlings were evaluated. At 41 degrees C, S. macrophylla seeds failed to germinate. A constant temperature of 29 degrees C under 24 h of light favors the germination process of seeds and initial seedling growth.