A preliminary agronomic evaluation of Stylosanthes species

Abstract

The relative merits of morphological and agronomic attributes for the classification of cultivars are discussed, and reasons are given for suggesting that a purely agronomic classification would be a valuable supplementary technique. A polythetic divisive program was used to classify 272 Stylosanthes accessions which had been grown in three spaced-plant experiments. Eleven agronomic attributes were used, and the agronomic groups generated were compared with the morphological-agronomic groups previously reported. The two classifications were broadly in agreement for all species except S. guyanensis, in which the agronomic classification revealed important variation. It is shown that the agronomic classification is an effective means of detecting agronomic heterogeneity within a morphological-agronomic group, and is particularly useful in elucidating inter-site differences in performance. It is suggested that the double classificatory approach provides a systematic method for the preliminary evaluation of accessions, and a rational means of selecting accessions for further experiments.