Variability in germination behaviour of Paspalum dilatatum Poir. seeds is genotype dependent

Dallisgrass (Paspalum dilatatum Poir.) is a warm-season grass, native to South America. Its adoption as a pasture crop has been hindered by low seed germination and slow establishment. However, variability in germination behaviour for this species has never been systematically analysed. For Paspalum spp., dry-storage and moist cold or warm pre-conditioning treatments have been reported as effective for the relief or breaking of seed dormancy. In the present work, seed germination responses at 32 degrees C were assayed for sixteen P. dilatatum genotypes, representing its known natural genetic variability, to two moist pre-conditioning treatments (at 5 and 20 degrees C) and without pre-conditioning, and three seed storage periods (0, 3 and 6 months). Pre-conditioning at 20 degrees C showed high germination percentages (>80%), with ratios equal to or higher than pre-conditioning at 5 degrees C, suggesting that cold is not required to break dormancy. Longer storage times resulted in increases in germination responses for most of the genotypes, while other biotypes showed no effect. Biotypes Virasoro and Chiru showed a remarkably different behaviour with higher germination percentages of untreated freshly harvested seeds. Our results show that diversity for traits involved in seed germination exists among naturally occurring P. dilatatum genotypes and the characterization of these traits should be addressed during ecotype characterization and evaluation of potential domesticates of this species.