Evaluation of Caribbean maize accessions to develop a core subset

Core subsets of germplasm collections facilitate their evaluation and use. Field evaluations were conducted to develop a core subset of Caribbean maize (Zea mays L.) accessions from the CIMMYT maize germplasm bank. Most accessions were from the West Indies and others were from Central and South America. The accessions were divided into two trials of 249 accessions and seven common checks that were evaluated in a 16 by 16 alpha-lattice design with two replications. The trials were planted in two seasons at two sites in Mexico during 1992 through 1994. Data were taken on agronomic and morphological traits and the combined analysis was performed by a mixed linear model. The adjusted means of plant height, ear height, senescence, ear diameter, ear length, days to silk, days to anthesis, moisture (%), rating on ease of shelling, and number of kernel rows were used to cluster accessions into homogeneous groups. Twelve non-overlapping dusters were formed and patterns of phenotypic diversity among and within clusters were determined using canonical discriminant analysis. A selection index based on yield (Mg ha(-1)), ear rot (%), erect plants (%), and moisture (%) was calculated for each accession. The upper 20% of the accessions (100 in total) which represent the phenotypic diversity of the clusters and have superior selection indexes were used to form a core subset of the Caribbean maize collection.