ABSTRACT
Summary The objectives of this study were to assess the forage potential of readily available world germ plasm of the genus Aeschynomene, which comprises 160 species; to compare some attributes of the commercial American jointvetch (Aeschynomene americana L.) with those of other accessions of the same and of other species; and to compare the seasonal growth pattern and response to phosphorus (P) of commercial jointvetch with two perennial tropical legumes. Evaluations were made of 342 accessions, including 25 identified species. Data collected from observational plots in 1978 and 1980 included initial flowering dates, plant vigor, and growth habit; from replicated plots, plant population and vigor; and from selected accessions, yield, nitrogen content, and digestibility. Comparison of yields at 20 and 60 kg/ha of P (2,000 kg/ha of lime) was made between jointvetch and siratro (Macroptilium atropurpureum Urb.) and Florida carpon desmodium (Desmodium heterocarpon L.). A majority of A. americana accessions flowered after 1 October, and height distribution was from less than 51 cm (18 accessions) to greater than 152 cm. Thus, it should be possible to select a later-flowering and more leafy plant than the commercial jointvetch. A. villosa, similar to but with shorter stems than A. americana, appeared to have potential for grazing. A. denticulata, A. falcata, A. elegans, A. evenia, A. fluitans, and A. paniculata warrant further study, although their establishment and persistence when grown with Digitaria decumbens Stent. were not always good. In June crude-protein content of commercial jointvetch (18.8%) was highest and digestibility among the best (52.1%) when compared with other accessions. These values ranged from 10.6% to 18.8% and 36.8% to 63.8%, respectively, among the accessions analyzed.
784Establishment-year production of commercial jointvetch was better than that of siratro and of carpon desmodium but was much less in June of the subsequent year. Yield response of jointvetch to P at either 20 or 60 kg/ha was greater than that of carpon desmodium at either of the two rates.
