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Draining of wetlands and their inadequate planning contribute greatly to the decline of hygrophilous vegetation. The arrival of invasive hygrophilous species, as noted recently for Pistia stratiotes L. in Al Jawahir Wadi (North Central Morocco) could also aggravate this situation. Surveys carried out in the watershed of this river show that P. stratiotes form spontaneous communities over a river-length of 10 km, twice of that reported in 2012, in spite of measures taken to limit its spread. Plants description on the basis of vegetative and reproductive criteria ascertains the permanent presence of this species upstream of the wadi, and reveals a succession of factors causing its intermittent suffocation downstream, including hydrological and planning hazards, and water pollution. The decontamination endeavors of Al Jawahir River and the exceptional propagating power of this species would represent a real threat to local water bodies for long.

Tomato (Lycopersicon esculentum Mill.) becomes one of the world's foremost vegetables, and its world production and consumption have increased fairly quickly. The capacity to induce oxidative stress in tomato plant, exposed to three xenobiotics such as alpha-cypermethrin, chlorpyriphos, and pirimicarb, was investigated by the evaluation of lipid peroxidation by measuring malondialdehyde (MDA) rate; also, we studied the response of tomato to this stress by assessing the response of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), ascorbate peroxidase (APX), glutathione-s-transferase (GST), and glutathione reductase (GR). The effect of the insecticides was observed using four concentrations (25, 50, 75, and 100%) for germinating seeds and only the recommended concentration in agriculture (100%) for growing plants. Our results show an important accumulation of MDA, demonstrating the increase of lipid peroxidation in consequence of the excessive reactive oxygen species (ROS) production due to insecticide treatment. In response to this oxidative stress in tomato seedlings and plants, the activities of antioxidant-enzyme system were generally enhanced. The electrophoretic analysis showed also the apparition of new isoenzymes as the case for CAT and POD.