The effect of fire and heat on germination of southeastern United States wildlife food plants with particular emphasis on the genus Cassia

Abstract

Prescribed burning is used in the southeastern United States to promote the growth of legume plants which produce seeds important as quail food. These seeds are characterized by a hard seed coat and the ability to remain dormant but viable for long periods of time. This study was conducted to determine the effect of heat on germination of seeds from several of these legume species and to investigate the factor responsible for maintaining dormancy. Eighteen species and two varieties of seeds were subjected to moist and dry heat treatment. Moist heat increased germination in eight species and two varieties of seeds, while dry heat increased germination in seven species and two varieties of seeds. The optimum moist heat temperature for maximum cumulative germination and germination rate of C. nictitans was 80°C. The factor responsible for maintaining dormancy appeared to be the hard seed coat, as removal of this structure by chemical or physical means increased germination. Chemical analysis of the seed coat showed that it contained a small amount of protein, and a relatively large amount of a uronic acid in addition to other carbohydrates. This hard seed coat may have been acquired after the seeds were physiologically mature with respect to germination.