Phenotypic and genetic variability in wild populations of dallis grass(Paspalum dilatatum   Poir.)

Dallis grass ( Paspalum dilatatum Poir.) is a warm season perennial grass of high forage value. The objective of this work was to get estimations of phenotypic variability among and within populations of dilatatum biotype of this species. Three places of the Northern Salado Basin (La Plata, Magdalena y Pereyra Iraola), province of Buenos Aires; Argentina, were sampled taking out whole plants. The material, kept in plastic pots, was used to measure six traits: number of nodes per tiller (NNM), flag leaf length (LLHB), flag leaf width (ALHB), rachis length of base spikelets (LREB), number of spikelets per panicle (NEP), and number of seed per base spikelets (NSEB). From 18 comparisons between population means (t test), 7 showed significant differences at the p = 0.01 level and 6 at the p = 0.05 level. The phenotypic variance within populations contained, in average, 26% of genetic variance. The degree of genetic determination (GDG) fluctuates in a rank from 0 to 52%. It is deduced, from these results, that the within populations variability did not exceed the among populations one. In spite of GDG values were not high, the total amount of available genetic variability is expected to be useful for breeding purposes, because of the apomictic mode of reproduction. The results of the principal component analysis were in agreement with those of the t test. The NNM, LLHB, LREB, and NSEB traits showed the larger discriminative power