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The objectives of the present study were to evaluate sideoats grama [Bouteloua curtipendula (Michx.) Torr.] populations, to set an ex situ plot, and to asses morphological diversity. From 2000 to 2003, 577 sideoats grama populations were collected in 13 Mexican States. In 177 established ecotypes, the following plant morphologic attributes were assessed: vigour, regrowth, forage texture, dry matter production potential, phenology, seed production potential, leaf density, tiller type and leaf:stem ratio. Variables were analysed through principal component analysis (PCA) using the PRINCOMP procedure. The first three components explained 62.9 % of the total observed variation. Principal component one (PC1) included characteristics related with growth and explained 36.4 % of variation; vigour, leaf density, and leaf:stem ratio were the most important variables. The PC2 included characteristics related with propagation and explained 15.1 % of variation; seed potential and tiller type were important variables. The PC3 explained 11.4 % of variation; forage texture and phenology were the most important variables. The PC1 and PC2 revealed the existence of six different groups. This dispersion reflects a wide morphological and genetic variation in this species; it was observed that this dispersion is not systematic, since it is possible to establish groups based on physiographic adaptation of ecotypes instead of locality or place of origin. It can be concluded that this variation is important while selecting the best forage characteristics in order to set up a genetic improvement program. [ABSTRACT FROM AUTHOR]

An efficient morphologic characterization of plants includes evaluation of forage traits. The objective was to analyze morphologic diversity in native populations of blue grama grass [Bouteloua gracilis (Willd. ex Kunth) Lag. ex Steud.] in Chihuahua. In 2006, 173 ecotypes were collected in Chihuahua and transplanted in La Campana Experimental Site. Ecotypes were evaluated through morphological traits and their population structure was defined. Principal component and cluster analysis were used for data analysis. The three first principal components explained 57.3 % of total variation. The PC1, PC2 and PC3 explained 35.3 %, 12.4 % and 9.52 % of the global variation, respectively. Most important variables for PC1 were forage yield, stem density, and plant height; for PC2 were spikelet width, inflorescence length and spikelet number; and for PC3, stem diameter, leaf width and spikelet length. The PC1 included variables related to growth capacity. The PC2 grouped variables associated to propagation and dispersion. The PC3 included variables related to biomass accumulation. Also, four groups were obtained from the 145 established ecotypes. Groups 1, II, III, and IV included 59, 24, 19, and 43 ecotypes, respectively. A high morphological diversity was observed and ecotypes with high forage potential were detected according to their morphological trails. Genetic variability in blue grama grass from Chihuahua is readily available and specimens having excellent forage characteristics could be used in range improvements programs. [ABSTRACT FROM AUTHOR]