Tropical Grasslands (2006) Volume 40, 157–164

Variation in chromosome number and its relationship with agronomic characteristics in a germplasm collection of Digitaria eriantha sensu lato

MARISA TONIOLO POZZOBON1, ALBRECHT GLATZLE3, IONARA FATIMA CONTERATO2, MARIA TERESA SCHIFINO-WITTMANN2 AND VANESSA GRUDSINSKE SMIDERLE2

1 Centro Nacional de Recursos Genéticos e Biotecnologia, Empresa Brasileira de Pesquisa Agropecuária, Brasìlia, Brazil
2 Departamento de Plantas Forrageiras e Agrometeorologia, Faculdade de Agronomia, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
3Iniciativa para la Investigaci—n y Transferencia de Tecnolog’a Agraria Sostenible, Loma Plata — Chaco, Paraguay

Abstract

In order to determine chromosome numbers and a possible correlation with some agronomic characteristics, accessions of the INTTAS (Iniciativa para la Investigación y Transferencia de Tecnología Agraria Sostenible, Chaco, Paraguay) seed-producing perennial D. eriantha germplasm collection were examined. The tetraploid level (2n = 36) was verified in 27 plants, 11 plants were diploid (2n = 18), 2 had 2n = 34 chromosomes, one 2n = 20 and in 3 plants possible accessory (B) chromosomes were detected. Meiotic behaviour was generally regular and percentage of viable pollen grains almost always exceeded 90% in all plants examined. No consistent correlations between phenotype or agronomic characters and chromosome numbers could be detected. However, 95% of the accessions originally collected from loamy soils were tetraploid or near tetraploid. Furthermore, diploid (2n = 18) or near diploid genotypes were much more likely to have a tufted (almost 60%), and the tetraploid or near tetraploid ones a stoloniferous (about 70%) growth habit. As preliminary on-farm observations suggest, accessions which seem to approach best the persistence of common Pangola grass under a wide range of environmental conditions belong to the groups with 2n = 36, 2n = 34 and 2n = 18 chromosomes.

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