THE EFFECT OF CHANGING MOISTURE CONTENT ON THE GERMINATION OF SLASH PINE SEED

Abstract

SUMMARY The germination characteristics and seed moisture content of slash pine seed which has been immersed in water and then dried in the air for various periods have been examined after each of the soaking and drying combinations. The moisture content of seed immersed in water rose rapidly initially but would take more than 7 days to reach a maximum of about 50% above the seeds' oven dry weight. The moisture content of moist seed left to dry under room conditions fell rapidly to the equilibrium moisture content of 10–14%; a consistent fall of 17% per 24 hours was recorded. The seed germination rate and germinative capacity rose with increasing moisture content, but no direct relationship between moisture content and germination could be found. Pre-soaked seed which was left to dry showed a decrease in germination rate and germinative, capacity, but this decrease is not directly related to the time elapsed before conditions again favour germination. Minimum germination values appeared to be related to the final drop in seed moisture content to the equilibrium, and germination values increased where the seed was held for longer than the time necessary to reach equilibrium moisture content. The moisture content of seed soaked for up to 80 hours might fall to the equilibrium value within 2–3 days, but soaked seed held in the open for 15 days germinated faster and more completely than unsoaked seed held in the open for a similar period. It was only under the one combination of conditions in which seed was soaked for 50 hours and held to dry for about 10 days, that the rate and degree of germination was markedly less than that of untreated seed.