Seed development and germination of Miscanthus sinensis
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Seed development and germination research was conducted to understand the biology of Miscanthus sinensis (Andersson). A thermogradient table was used to determine whether M. sinensis germinated better under constant or alternating temperature conditions and which temperature treatments provided the best environment for maximum seed germination percentage for the species. It was determined that M. sinensis germinated best under alternating temperatures and achieved the highest germination with a combination of 22 and 16°C for 16 and 8 h. Results from the thermogradient table experiment were used to guide the design of the second experiment. The second experiment explored the effect of temperature combinations, light, and dormancy breaking techniques on seed germination and was used to determine a base for establishing a standard germination protocol for M. sinensis. Alternating temperatures commonly used by seed laboratories (15/25, 15/30, 20/30°C for 16/ 8 h) were compared to the best germination temperature combination from the first experiment (22/16°C for 16/8 h) obtained using the thermogradient table. In addition, seeds were subjected to either 8 h of light during the period corresponding to the higher germination temperature, or 24 h of dark. The influence of dormancy breaking techniques on seed germination was also explored. A 500 mg L-1 GA3, 2000 mg L-1 KNO3, and a 5°C prechill for 7 d were compared to an untreated control. The highest germination of freshly harvested seeds was recorded when germinated using 20/30°C for 16/8 h. There was no significant difference in the germination of one-year-old seed regardless of the germination temperature treatment. Across all seed lots and years there was no significant difference in the germination percentage between seeds germinated using light and those kept in the dark. The germination percentage of seeds treated with GA3 and prechill treatments was significantly higher than the germination percentage of seeds treated with KNO3 and control treatments. Finally, an experiment was conducted to examine the water relations and seed development of M. sinensis. Plants were grown in the greenhouse and crossed to produce seed. Light microscopy was used to create a seed development timeline. Seeds of M. sinensis reached physiological maturity at 30 d after pollination and moisture content of 33%. These results give us a better understanding of the biology of M. sinensis seeds. In the future when M. sinensis becomes a more widely cultivated species, these results will help seed producers and farmers make informed decisions on seed production and quality.