In vitro assays to evaluate the tolerance of agricultural plants to organochlorine herbicides

CUADRADO, V; MERINI, LJ; FLOCCO, CG; GIULIETTI, AM

San Carlos de Bariloche - Rio Negro

Congreso; XXXIX Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (S.A.I.B.).; 2003

Phenoxy and triazinic herbicides (2,4-D and atrazine) are two of the most employed pesticides in Argentine agriculture. Due to their physicochemical properties and their extensive use there is a great risk of soil and water contamination. To investigate the tolerance of some important crops to these herbicides for phytoremediation purposes, in vitro assays with young plants (seedlings) were carried out. Alfalfa and maize seedlings were exposed to 2,4-D and atrazine. The seeds were surface sterilized before sowing in 390 ml glass flasks on Murashige-Skoog medium containing 10 g/l sucrose, 4 g/l agar and different concentrations of the herbicides. Incubation was carried out at 24±2 ºC, under a 16/8 h photoperiod. After 10 days for maize and 13 days for alfalfa, the individual seedlings were harvested, washed and the following tolerance parameters were evaluated: root length, shoot length, shoot fresh weight and percent germination. The results showed a more marked toxic effect of 2,4-D in comparison with that of atrazine. 2,4-D concentrations of approximately 0.1 ppm and between 0.01-0.05 ppm diminished the plants parameters in 50% in maize and alfalfa, respectively. On the other hand, only high atrazine concentrations, approximately 25 ppm with alfalfa and 50-75 ppm with maize, produced a 50 % reduction in the evaluated parameters. Knowing the herbicides concentrations that the plants can tolerate is a necessary step for developing phytoremediation strategies based on the eco-engineering the rhizosphere environment.