Effects of seed bed conditions on the germination of four Stylosanthes species in the Northern Territory

Abstract

Since the proposed use of low input management practices in the Northern Territory will require the establishment of Stylosanthes species in the native grasslands with the least possible disturbance, the effects of soil surface, soil type and seed treatments on the germination of four Stylosanthes species were studied. The species were the annual S. humilis, the facultative perennial S. hamara cv. Verano, and two obligate perennials, S. scabra CPI 40289 and S. viscosa CPI34904. The study was carried out on microplots in burnt and unburnt pasture near Katherine in the Northern Territory. Although all species germinated in both burnt and unburnt grassland, germination was much better under the grass sward. The two perennial species germinated much more slowly than either S. humilis or S. hamata, and the removal of grass cover caused low germination of these species, especially under the poor moisture conditions existing on the surface of sandy soils.

Under the existing method of establishment with burning late in the dry season followed by sowing in the early wet season, the germination of the perennials S. scabra and S. viscosa will not attain the same levels as that of S. hamata and S. humilis. Our results suggest that field germination of the perennials could be enhanced by either pretreating the seed to improve its potential rate of germination, or by sowing later in the wet season to take advantage of the greater probability of prolonged moisture conditions.