Responses of Seeds of Pinus taeda & P. strobus to Light

Abstract

Seeds of loblolly pine, Pinus taeda, and of white pine, P. strobus were tested for their responses to red and far-red radiation after they were stratified in darkness for different periods at 5[degree] and at 15[degree]C. After irradiation the seeds were germinated in darkness at 25[degree]. A high percentage of the seeds of both species germinated in response to a single, brief exposure to red light following partial afterripening. The actions of the red and far-red radiations on the germination of the seeds were immediately and repeatedly reversible. Continuous or repeated exposures to light shortened the period of stratification necessary for complete germination. Stratification was more effective at 5[degree]C than at 15[degree]. Lengthening the period of stratification increased germination in total darkness, increased the sensitivity of the seeds to red light, and decreased the sensitivity to far red.