Effects of trifluralin on peanut plants were studied in glasshouse conditions, aiming to reproduce malformation simptoms observed in field conditions. Four commercial formulations of trifluralin were applied to soil at rates of 1.5, 3.0 and 6.0 1/ha. Pots with two plants were main tained during 29 days in glasshouse and the following recordings were carried out: dry weigth of roots, stems, petioles and leaflets: number of leaflets; leaf area and main stem lenghth. External and internal morphological chan ges were examined. The observations showed a reduction of dry matter of subterranean parts following the increment on the herbicidedosage. Leave were not affected by the herbicide. The effects were related to dosage increase rather to different commercial formulation types. The higher herbicide dosages caused morphological alterations like reduzed root number, with short and thick secondaty roots. Hypocotyl emitted adventiciones roots until cotyledonary node. Treatment of 3.0 1/ha showed secondaty roots thicker than 1.5 1/ ha dosage. Histological observations of tissues in hypocotyl region showed very thick cortical parenchyma due to increase cellular layers number. Modification in cell shape and in other tissues we rent observed.
trifluralin; rates; peanut; morphologycal and cytological modifications