Publication Date

1989

Description

Although Ohashi (1973) classified Desmodium ovalifolium Wall. as synonimous with D. heterocarpon (L.) DC. and placed both in the same subspecies and variety, most forage resear­chers have chosen to maintain species rank for both taxa. Ohashi's criteria for lumping these two taxa was inflorescences densely flowered with distinctly hooked-hairy pods ; however, germplasm characterization by CIAT (1981) has identified growth habit and flowering pattern as other more complex traits by which these species differ. Desmodium ovalifolium has been shown to have potential for pasture use in the Llanos of Columbia and other acid soil sites (CIAT, 1981). A cultivar of D. heterocarpon 'Florida' was released in Florida in 1979, but because of difficulties associated with establishment and root­knot nematode susceptibility it has not received widespread commercial acceptance. Considerable germplasm of both of the above species has been collected and assembled by the CIAT Tropical Pastures Program in recent years. The objectives of this research were to (1) characterize the differences in plant morphology, flowering date, and reproductive habit within this germplasm, (2) produce hybrids between D. ovalifolium and D. heterocarpon types and among diverse D. ovalifolium types, and (3) evaluate Fl and F2 individuals for cytological behavior and morphological segregation.

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Evaluation and Hybridization of Germplasm in the Desmodium Hetercarpon- D. Ovalifolium Species Complex

Although Ohashi (1973) classified Desmodium ovalifolium Wall. as synonimous with D. heterocarpon (L.) DC. and placed both in the same subspecies and variety, most forage resear­chers have chosen to maintain species rank for both taxa. Ohashi's criteria for lumping these two taxa was inflorescences densely flowered with distinctly hooked-hairy pods ; however, germplasm characterization by CIAT (1981) has identified growth habit and flowering pattern as other more complex traits by which these species differ. Desmodium ovalifolium has been shown to have potential for pasture use in the Llanos of Columbia and other acid soil sites (CIAT, 1981). A cultivar of D. heterocarpon 'Florida' was released in Florida in 1979, but because of difficulties associated with establishment and root­knot nematode susceptibility it has not received widespread commercial acceptance. Considerable germplasm of both of the above species has been collected and assembled by the CIAT Tropical Pastures Program in recent years. The objectives of this research were to (1) characterize the differences in plant morphology, flowering date, and reproductive habit within this germplasm, (2) produce hybrids between D. ovalifolium and D. heterocarpon types and among diverse D. ovalifolium types, and (3) evaluate Fl and F2 individuals for cytological behavior and morphological segregation.