Contagens cromossômicas em espécies brasileiras de Paspalum L. (Gramineae)

Abstract

Germplasm accessions obtained in collecting missions covering ali the five regions of Brazil were submitted to cytological analysis, either in mitosis or meiosis. Chromosome numbers are reported from 107 accessions of 33 species, representative of 13 of the informal taxonomic groups, in which the genus is traditionally divided. In the Plicatula group, under intensive taxonomic investigation, 27 accessions are mentioned without any specific identification. The Southem region is very well represented, with 65 accessions, followed by the West Central region, with 33. The chromosome numbers of P. filifolium (2n = 20), P. hartwegianum (2n = 60), P. rhodopedum (2n = 40) and P. wettsteinii (2n = 40 and 60) are reported for the first time. Also new are the reports of 2n = 50 for P. plenum and for a yellow-anthered form of P. dilatatum. The new findings include an additional diploid accession of P. plicatulum (2n = 20) and a second accession of P. mandiocanum with 2n = 50, a number in disagreement with the most frequent hexaploid level in this species. Additional data confirm previous counts, thus extending their geographic amplitude.