Sward tests of some Stylosanthes guyanensis accessions in tropical and subtropical environments

Abstract

An experiment is described in which 48 S. guyanensis accessions, comprising 11 morphological-agronomic (M–A) subgroups, were grown with an associated grass (Urochloa mosarnbicensis or Setaria anceps cv. Narok) for 3 years in small mown swards at up to nine different tropical and subtropical environments in northern Australia. The experiment was non-orthogonal, but could be analysed as three substantially orthogonal subsets; simple ranking techniques were used to explore the complete data set.

Significant differences were shown to exist between the M–A groups, but these were less clear-cut than in other Stylosanthes species; the S. guyanensis groups are agronomically more variable. Nevertheless, the results have indicated the existence of five accessions which appear able to outyield any existing cultivar in the appropriate environments. These arc CPI 34911 (M–A group 8A) over a wide range of tropical sites; 40255 (10B) and Q8231 (8A), less wide-ranging than 34911 but outyielding it at a site with a long growing season; and 46590 and 46589C (both 8B), In the high-rainfall subtropics. All would merit more extended trials.