The Effect of Desiccation on the Longevity of Seeds of Araucaria hunsteinii and A. cunninghamii

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Abstract
Seeds of Araucaria hunsteinii K. Schum. dried quicker at 29°C than at 19°C and quicker with the seed-coat removed than when intact; seeds enclosed in polyethylene bags increased in moisture content. At 15°C, seeds in a flow of air dried quicker than seeds in a box with silica gel, which in turn dried quicker than seeds in a box with no desiccant. No loss of germination ability occurred on drying fresh seed from 53 to about 32 per cent moisture content (fresh weight basis); during further desiccation the percentage germination was related to percentage moisture content in the form of a sigmoid curve, culminating in a complete failure to germinate at approximately 14 per cent moisture content. A consistent relationship was observed for all treatments and the mean critical moisture content for seed death (failure to germinate) was near 23 per cent. Excised embryos grew on 1 per cent agar but died if previously subjected to 14 h of desiccation at 15°C. In contrast, no relationship was found between germination and moisture content of A. cunninghamii D. Don on desiccation from 21 to 7 per cent moisture content. Possible causes for the observed difference in response to desiccation are discussed and methods for seed storage are considered.

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