Physiological Study of Maple Seeds

Abstract

River maple 1. Seeds lose their viability when the water content is reduced to 30-34 per cent. 2. Temperature seems to play no part in determining the critical point of water loss. Higher temperatures only hasten the rate at which the point of desiccation is attained. 3. Respiratory activity in the desiccating seeds at 25⚬C. first decreases slightly, then rises to a maximum, then gradually falls to zero as desiccation progresses. 4. After a slight initial increase, catalase activity gradually decreases in the desiccating seeds. Catalase activity increases enormously during the early stages of germination. 5. Seeds of a river maple may be kept in a vigorous viable condition for a considerable period of time at low temperatures (0⚬C.) stored over water. 6. There is a gradual decrease in peroxidase activity accompanying desiccation. Sugar maple 1. Seeds after-ripen best at temperatures near 5⚬C., with a good supply of oxygen and moisture. 2. With after-ripening the seeds show a considerable increase in free reducing sugars. 3. Catalase activity increases greatly with after-ripening and germination; there is also a slight increase in peroxidase activity. 4. Both the dormant and after-ripened seeds have a reaction that is distinctly alkaline; this holds for the hypocotyl as well as for the entire embryo. 5. Fully after-ripened seeds will remain in this condition for a long time if kept moist at -5⚬C.