The effect of high temperature pretreatments on germination of Townsville stylo seed material

Abstract

Townsville stylo cv. Gordon dehulled seed and intact pods were exposed to temperatures ranging from 40° to 11 5°C for between 12 and 48 hours in the expectation that a method of reducing hardseededness could be devised. Dry heat temperatures of 75° and 95°C markedly decreased the level of hardseededness in both dehulled seed and intact pods. A temperature of 11 5°C for 12 hours was sufficient to kill all seeds and pods. Fifty per cent germination was achieved after 2.5 days for dehulled seeds and after 5 days for pods exposed to a pretreatment of 95°C. Untreated scarified dehulled seeds took only 1.5 days to achieve 50 per cent germination. It was suggested that a suitable heat pretreatment on Townsville stylo pods should result in a seed material with a soft-seed level similar to dehulled scarified seed, yet with the pods still retaining considerable immunity from 'false starts' to the wet season.