CYTOLOGY AND REPRODUCTIVE-BEHAVIOR OF DIPLOID, TETRAPLOID AND HEXAPLOID GERMPLASM ACCESSIONS OF A WILD FORAGE GRASS - PASPALUM COMPRESSIFOLIUM

Fourteen germplasm accessions of Paspalum compressifolium native from southern Brazil were cytologically and embryologically analysed. The s tudy revealed that one accession was diploid (2n = 20), twelve were te traploid (2n = 40) and one was hexaploid (2n = 60). This is the first report of diploid and hexaploid cytotypes for this species. Studies on microsporogenesis, megasporogenesis, and embryo sac development indic ated that the diploid cytotype had regular meiotic behavior and reprod uces sexually. Tetraploid cytotype usually had an important proportion of chromosomes that associated as quadrivalents during meiosis and re produced by mean of aposporous apomixis. The hexaploid cytotype showed irregular meiotic behavior with about one third of the chromosomes as sociated as multivalents and reproduced by aposporous apomixis. Thus, P. compressifolium could be an agamic complex. Breeding in this comple x is possible due to the presence of diploid sexuals which can be trea ted by colchicine and pollinated by apomicts.