Variation within Stylosanthes sp. aff. scabra and comparison with its closest allies, S. scabra and S. hamata

Abstract

Forty Stylosanthes scabra, S. hamata, and S. sp. aff. scabra lines were grown at CSIRO Lansdown Research Station, North Queensland. Morphological features were grouped with the numerical classification program PATN. Agronomical attributes were recorded and analysed for each group. The resulting 5 groups were largely homogeneous by species. Seed colour, the presence of leaf bristles and stipule horn lateral bristles, stem and inflorescence viscidity, growth habit, and stem length and thickness were important features separating the groups. There were significant differences in yield and seed yield between the groups. Hardseededness ranged from 2 to 79% and the low level of hardseededness in many high-yielding lines is cause for concern. Stylosanthes sp. aff. scabra was found to differ from S. scabra in its narrower and hairless leaves and the presence of stipule horn lateral bristles in combination with a very short or an absent stipule horn terminal bristle. Apart from 1 line, the S. sp. aff. scabra lines fell within 2 groups: a prostrate, low-yielding, anthracnose-susceptible group; and an erect, high-yielding, anthracnose-resistant group. Lines from the second group will be released for commercial use.