A Comparative Study of Root System Architecture in Seedlings of Brachypodium spp. Using Three Plant Growth Supports

This work reports a rapid procedure of comparing root development among different genotypes of Brachypodium spp., using three plant growth supports: gel chamber, 'Termita' chamber and Whatman paper. Eight variables of the root system architecture (RSA) (number of seminal roots, number of lateral roots, total length of the roots, length of the primary root, mean diameter of the roots, mean diameter of the primary root, total surface area and total volume of the roots) were studied in seedling of four genotypes each of Brachypodium distachyon, B. stacei and B. hybridum. Correlations between pairs of growth supports in terms of the eight variables examined were highly significant. In all three supports, B. stacei showed the greatest root system development while B. distachyon showed the least; B. hybridum, an allotetraploid species derived from hybridization between B. distachyon and B. stacei, showed intermediate development. ANOVA and LSD tests showed that significant differences exist between the supports, species and genotypes with respect to all the variables analysed. A cluster analysis was conducted to determine if the RSA traits could be used to differentiate the species and genotypes of Brachypodium. This analysis allowed differentiated between the three species and twelve genotypes of Brachypodium spp., although a certain overlap between species was observed. The Whatman paper support was the easiest to use, and is recommended for the characterization of large collections of genotypes.