A method for establishing a core collection of Saccharum officinarum L. germplasm based on quantitative-morphological data

A technique is proposed for establishing a representative core collection o f S. officinarum accessions from the world collection of sugarcane germplas m maintained at the Sugarcane Breeding Institute-Research Centre, Cannanore , India. In the proposed method, the accessions were first sorted based on their relative contributions to the total variability by means of principal component scores based on a set of quantitative characters. Then, the cumu lative proportion of their contributions to the total variance was computed . A logistic regression model was fitted to evaluate the functional relatio nship between the cumulative proportion of variance and the number of acces sions. The size of the core set was decided as the inflection point on that fitted curve, i.e., the point beyond which the rate of increase in cumulat ive proportion of variability contributed by an accession began to decline. A method for eliminating entries with a high degree of similarity from the selected core set is also proposed.