Morphological Characterisation and Cyanide Content Determination in Phaseolus lunatus Linn. (Lima Beans) Accessions

Lima bean (Phaseolus lunatus Linn.) is one of the important legumes in developing countries. The study was carried out to evaluate the morphological characters and determine the amount of cyanide in lima beans. A total of 15 Lima bean accessions were obtained from the genebank of Genetic Resource Centre, International Institute of Tropical Agriculture (IITA) Ibadan, Oyo state, Nigeria and laid in Complete Randomised Design with three replicates. Morphological characters were evaluated based on the descriptors proposed by the International Plant Genetic Resources Institute, while hydrogen cyanide (HCN) content was determined using alkaline picrate colorimetric method. Six of the accessions (2005-014, 2006-003A, 2006-003B, 2006- 005A, PS-16 and TPl-2429) having best yield, moderate yield and lowest yield were selected for cyanide determination. Result showed that the accessions varied morphologically. The highest yielding accessions were TPl-2429, 2005- 014, 2006-003A and 2005-011, while 2006-003B and TPl-178 have moderate yields. Accession 2005-014 had the highest growth characters, followed by 2006-015 and 2006-003A which showed good quality. Lower amounts of cyanide were detected in 2005-014 and PS-16 accessions, while 2006-003A, 2006-003B and 2006-005A accessions did not show cyanide contents. Therefore, TPl-2429, 2006-003A and 2005-011 accessions which showed higher growth and yield with no cyanide content could be further improved in breeding of lima beans.