Effect of boiling water treatment on hardseededness and germination in some Stylosanthes species

Abstract

Levels of hardseededness in commercial seed lots of Stylosanthes species were determined. Levels varied from 0 to 98%, but there were substantial proportions of hard seed in some seed lots of all species. Median values were 40, 55, 63 and 72% for S. guianensis, S. hamata, S. scabra and S. humilis, respectively. Immersion of seed pods in boiling water for 1 min resulted in almost complete breakdown of hardseededness in all species. In S. hamata this generally resulted in reasonable germination, but in S. guianensis, S. scabra and S. humilis it was accompanied by death of many seeds. Longer periods of immersion killed an increasing proportion of seed. Treatment in boiling water could be used to reduce hard-seed levels in S. hamata (but not other species) but prior testing of a small sample would be necessary as many seeds were killed in 1 S. hamata seed lot (of 7 tested).