Physiological Changes in Seeds of Solanum paniculatum L. during Heat Stress

Physiological changes occur in seeds before and during the germination process when subjected to high temperatures. Considering that Solanum paniculatum presents an adaptation to different environments, the aim of this study was to evaluate physiological changes of level of heat stress tolerance in seeds of S. paniculatum, before and during germination. Four-time periods (12, 24, 48 and 72 h for the 45°C temperature) were tested before and after the germination process in seeds of S. paniculatum. The degree of humidity, imbibition curve, percentage of germination, mean germination time (MGT) and germination uniformity coefficient (T7525), relative frequency at different times of temperature exposure of 45°C. The seeds of S. paniculatum, characterized in the period of 432 h (18 days), present the three-phase water absorption pattern. Seeds submitted to heat stress during the germination process presented higher tolerance than those submitted to high temperatures before imbibition, suggesting greater stability of the physiological constituents of the seeds to stress. Germinability of S. paniculatum can be intensified even under stress and suggests a broader frequency distribution than seeds that did not undergo stress during germination.