Germination characteristics of tropical and sub-tropical rangeland species

A study was made of the germination characteristics of a broad spectrum of rangeland species by studying their behaviour under different conditions. Seeds of common species (both native and exotic) were collected from tropical (north-east Queensland) (36 species) and sub-tropical areas (south-east Queensland) (47 species). The seeds were exposed to three storage treatments: in a shade-house for 60 months, in a seed store (tropical collection) or freezer (sub-tropical collection) for 60 months, or in an oven with fluctuating temperatures (25/60 degrees C) for 3 (tropical collection) or 4 (subtropical collection) months. Germination was tested during and after storage under standard conditions of 30/25 degrees C (tropical collection) or 30/20 degrees C (sub-tropical collection) with light during the 12-h period of higher temperature. In addition, germination of the sub-tropical collection was tested in the dark and at lower temperature (20/10 degrees C). The species were divided into groups on the basis of changes in germination during storage in a shade-house or in a seed store or freezer. The species showed a wide range of germination behaviour, changes during storage, and responses to germination conditions. Differences in the responses of seed lots of the same species in the two collections show that care is needed when extrapolating results from one experiment to other collections and regions.