Genetic and morphological characterization of Acroceras macrum Stapf.

Abstract

Acroceras macrum is a warm-season grass used for pas-tures, and it has high nutritive value. The scarcegenetic and reproductive information about this grassis limiting its breeding for forage. The objective of thisresearch was to determine the number of genotypesand cytotypes present in a collection established inArgentina, and to estimate the diversity of this speciesbased on molecular markers, and morphological andagronomic characteristics. The number of genotypesamong forty-seven accessions was determined usingISSR markers. The identified genotypes were furthercharacterized for ploidy levels. In addition, the geneticdistances among them were estimated with ISSRmarkers. They were also propagated and planted intothe field following a randomized complete blockdesign with four replications, and a group of sixteenmorphological and agronomic variables were evalu-ated. A total of twenty-seven genotypes were identi-fied in this collection; twenty-two genotypes weretetraploid (2n = 4x = 36) and five were hexaploid(2n = 6x = 54). These two cytotypes were foundclearly separated by both genetic and phenotypic char-acteristics. Above-ground biomass, internode length,initial growth and number of spikelets per inflores-cence were the most variable traits. The high diversitypresent in this collection will allow for the initiationof a breeding programme for A. macrum.