Seed dormancy dynamics and germination characteristics of Solanum nigrum

Four experiments were conducted to study seed dormancy and germination requirements in Solanum nigrum. In Expt 1, seeds were stratified at different constant and stepwise rising temperatures and their germinability was tested at three germination regimes at weekly intervals. In Expts 2-4, seeds dry stored at 4 degrees C and stratified at 5 and 15 degrees C were tested at constant temperatures, as well as fluctuating temperatures with constant and increasing amplitudes. Results suggest that the rate of dormancy release increased with increasing temperatures ranging from 4.5 to 18.6 degrees C. However, prolonged strati. cation at higher temperatures caused subsequent induction of dormancy. When tested at constant temperatures, stratified seeds germinated between 18 and 34 degrees C, with the optimum between 26 and 30 degrees C, while dry-stored seeds showed no germination. Fluctuating temperatures, with amplitudes ranging from 5 to 15 degrees C, promoted germination of seeds from all treatments. The dormancy dynamics and germination characteristics of the species will have implications for its survival and establishment. This information can be used to predict time of emergence and, thus, improve control of the species in weed management systems.