Classification of Kentucky bluegrass genotypes grown as spaced-plants

The apomictic breeding behavior of Poa pratensis L. provides an opportunity to study many unique genotypes that can vary dramatically in characteristi cs such as disease resistance, stress tolerance and growth habit. The class ification of Kentucky bluegrass into types is based on common growth and st ress performance characteristics gathered from field turf trials. These cla ssification types include the Compact, Bellevue, Mid-Atlantic, BVMG ('Baron ,'Victa', 'Merit', and 'Gnome'), Common, and Aggressive types. A spaced-pla nt nursery trial was established in May 1996 to quantify morphological and growth characteristics of 45 cultivars and selections representing the majo r types of Kentucky bluegrass. Plant height, panicle height, flag leaf heig ht and length, subtending leaf length and width, rhizome spread, and longes t extending rhizome were measured 10 days after anthesis. Compact type cult ivars had a lower, more prostrate growth habit than the Common, Mid-Atlanti c, and Bellevue types. Mid-Atlantic type cultivars had a wider rhizome spre ad than Compact type cultivars, Principal component analysis of morphologic al measurements made on spaced-plants supports the classification types of the Common, Compact, Bellevue, Mid-Atlantic, and BVMG, but not necessarily the Aggressive type.