Moisture and temperature in relation to seed structure and germination of sugar pine (Pinus lambertiana Dougl.)

Baron, FJ

Dep Biol Sci, Duquesne Univ, Pittsburgh, PA 15219, USA

. 65(7). 1978. 804-810.

The typical, irregular, delayed germination of sugar pine seeds was studied under different conditions of environment and seed dissection. Individual seeds showed a 3-phase pattern of water uptake which was obscured when average values for groups of seeds were used. Stratification at 5 degrees C slowed the rate of imbibition as well as the growth rate, but when followed after 3 mo. by a return to 20 degrees C, germination was uniformly rapid. Complete removal of the seed coats yielded prompt germination without stratification. The thin layer of the inner coat was a critical factor. Slitting this layer indicated less significance for gas exchange or mechanical restraint than for a restriction upon the rate of water uptake. Regardless of the method of seed treatment, the visible stages of germination consistently occurred within well-defined levels of water uptake. The delicate balance between water entry and use and the internal distribution of water within seed components should be evaluated, rather than a mere expression of the total amount of water in a seed.