Análisis de la variabilidad de caracteres de raíz en poblaciones de alfalfa (Medicago sativa L.) con alto número de raíces laterales

in order to provide some level of tolerance to the alfalfa root curculio in argentina, the improvement directed to increasing the number of secondary roots could be important. the objectives of this work were to estimate under four environmental conditions, variance components, trait heritabilities (h) and correlations among aerial and root traits in 10 alfalfa populations ranging from 6 to 9 fall dormancy, obtained by the alfalfa breeding program at the exp. stn. of manfredi- inta. the evaluated traits were average forage yield per cut (bp), taproot diameter (dp), number of lateral roots (nrlr), lateral root diameter (drlr) and branched-type root system (r). considerable variation for all traits was detected across all environments. there was no correlation between bp and most of root traits in almost every environmental condition, indicating that selection for yield and root traits could be independently managed. under irrigation, dp was positively (r =0,47; p<0,01) correlated with bp. both drlr and nrlr exhibited little variability and appeared to be little or not influenced by the environment. non-dormant populations had the lowest number of secondary roots, while the moderately-dormant populations presented the highest numbers. r reached a much higher expression under dryland conditions than under irrigation. bp and dp had high h values.