Morphoagronomic variation in natural populations of Trifolium riograndense (Burkart)

Abstract

Several species of Trifolium are widely cultivated as forage for animals and green manure. This work aimed to characterize and estimate through morphological and agronomic traits the genetic diversity of natural populations of T. riograndense, an important forage legume from native pastures of the state of Rio Grande do Sul, Brazil. Plant height and diameter, number of primary and secondary stolons, stolon length, number of nodes per primary stolon, internode length, primary stolon diameter, leaf area, petiole length and dry matter production were analyzed in 29 accessions. The first five attributes and dry matter production were evaluated twice. A broad phenotypic variability was observed for almost all characteristics. Positive correlations occurred between petiole length and leaf area (r = 0.68), petiole length and plant height in the first evaluation (0.63), stolon length and plant height (0.58), total dry matter and plant diameter (0.61), and total dry matter and plant height in the second evaluation (0.55). The two most divergent accessions were collected in the same physiographic region and the two less divergent ones in different regions. A dissimilarity dendrogram separated four groups. Accessions collected in a region where T. riograndense is abundant were found to belong to different groups outlining the great variability of this native forage legume. Dry matter production in the first cut was the characteristic that most contributed (20.80%) to accessions divergence followed by number of secondary stolons (12.30%), leaf area (11.07%), and number of nodes per primary stolon (10.93%). Key words: forage legume, genetic variability, morphology, plant breeding Variação morfoagronômica em populações naturais de Trifolium riograndense (Burkart)RESUMO: Várias espécies de Trifolium são extensivamente cultivadas como forragem ou adubo verde. Caracterizaram-se e estimaram-se, por meio de atributos morfológicos e agronômicos, a diversidade genética de populações naturais de T. riograndense, importante leguminosa forrageira nativa dos campos naturais do Rio Grande do Sul. Estatura e diâmetro das plantas, número de estolões primários e secundários, comprimento do estolão primário, número de nós por estolão, comprimento dos entrenós, diâmetro de estolão, área foliar, tamanho do pecíolo e produção de massa seca foram avaliados em 29 acessos. Os cinco primeiros atributos e a produção de massa seca foram avaliados duas vezes. Ampla variabilidade fenotípica foi observada para quase todas as características. Ocorreram correlações positivas entre tamanho do pecíolo e área foliar (r = 0,68), tamanho do pecíolo e estatura (0,63) na primeira avaliação, e comprimento do estolão e estatura (0,58), massa seca total e diâmetro da planta (0,61) e massa seca total e estatura (0,55) na segunda avaliação. Os dois acessos mais divergentes foram coletados na mesma região fisiográfica e os dois menos divergentes em regiões diferentes. O dendrograma de dissimilaridade genética separou quatro grupos. Acessos coletados em uma r...

Microsatellite diversity and chromosome number in natural populations of Trifolium riograndense Burkart

“…In Trifolium repens, Zhang et al (2010) observed some relationship between genetic diversity and geographical origin and in Lotus corniculatus genetic distances and place of collection were highly correlated (Sardaro et al, 2008). Conterato et al (2010a) evaluated morphological and agronomically most of the accessions also studied in this study and found high diversity for these characteristics, not correlated with geographical origin. The groups formed by the use of these morphoagronomic descriptors, by the Tocher methods, were nor the same as those of the present work, indicating no clear relation between morphological and molecular variability, same as found in, for example, Trifolium pratense (Greene et al, 2004) and Lotus corniculatus (Steiner and Los Santos, 2001).…”

“…For plant breeders, the species is attractive due to its qualities as perenity, cold tolerance and tolerance to soils with high aluminum and manganese contents (Kappel, 1967;Moraes et al, 1989). Previous studies with few accessions of the species disclosed a high intraspecific variation when isoenzymatic (Lange and Schifino-Wittmann, 2000), SSR markers and morphoagronomic characteristics (Conterato et al, 2010a) were used.…”

“…Despite previous studies with the species, no comprehensive study to assess its genetic variability with molecular markers has been carried on. Therefore, this study aimed to evaluate genetic diversity using SSR markers, as well as verify the existence, or not, of intraspecific variability in chromosome numbers, in natural populations of T. riograndense (most of them also studied morphologically and agronomically by Conterato et al (2010a).…”