Germination characteristics in tropical provenances of Allocasuarina littoralis and A. torulosa

Abstract

Germination of tropical provenances of Allocasuarina littoralis (Salisb.) L. Johnson and A. torulosa (Ait.) L. Johnson as affected by time of seed collection, light, temperature and storage conditions were examined. Changes in viability with seed development, as indicated by colour, were described. As seed colour darkened, viability increased, then levelled off or declined. The germination level of each provenance was found to be constant between 15 and 35°C, but germination rate reached an optimum between 25 and 35°C. Greater variation in germination rate was found in provenances of A. littoralis and of A. torulosa, with germination being delayed by up to 11.8 days in A. littoralis in the absence of light. Seed of both species was stored for 6 months at a range of temperatures and humidities without significant effect on germination level. Median germination time is recommended as a statistically testable measure of germination rate. Guidelines are given for handling seed for germination with respect to tropical agroforestry programmes.