Tropical Grasslands (1992) Volume 26, 145155
Selection of morphological traits for characterisation of elephant grass accessions
F.A. TCACENCO1 and G.N. LANCE2
1EMPASC, Estaçäo Experimental de Itajaí, Santa Catarina, Brazil
Elephant grass (Pennisetum purpureum Schum.) is an important forage species for the tropics. Several cultivars have been developed and released but there is little information on their morphological characterisation. The present experiment evaluated the usefulness of 89 morphological characters for this purpose. Nine accessions or cultivars were used. Leaf, stem and inflorescence characters were measured at the vegetative and reproductive phases. Data were submitted to univariate analysis of variance (ANOVA), as well as to multivariate analyses (cluster and principal component analysis — PCA) and to an algorithm that evaluates the attribute contribution to a classification. All characters measured at the reproductive phase showed significant differences between accessions in the ANOVA. Those with high Cramer value were selected for further analyses (PCA and cluster). Seven out of the 25 reproductive characters could be selected which would yield a good separation between accessions. Characters measured at the vegetative phase also showed significant differences between accessions. Selection of only a few of them produced a good discrimination. In both cases, considerable variation between plants from a given accession was observed, therefore all analyses should be based on more than one individual or on average values from several individuals of the same accession. For practical purposes, one would select a list of characters out of those maintained in the final analyses. The selected characters would be those easiest to measure. Characters that are either difficult to evaluate or that can introduce bias due to subjectivity should be avoided. Amongst the more useful characters are: diameter of culms and nodes, leaf size, arista and spikelet length, diameter of rachis, leaf pubescence, ligule size, colour and pubescence, and roughness and indentation of leaf margins.