Physiological and biochemical response of wheat seedlings to organic pollutant 1, 2, 4-trichlorobenzene

The growth and antioxidant defence responses in wheat (Triticum aestivum L.) seedlings grown hydroponically with 0 (control), 10, 20, 40 and 80 mg L-1 of 1, 2, 4-trichlorobenzene (TCB) were examined to better understand plant physiological and biochemical responses to chlorinated benzenes. Fresh and dry shoot weight, chlorophyll and soluble protein contents decreased significantly with increasing TCB concentration. In contrast, the rate of production of O-2(-) in the roots increased at lower TCB concentrations but decreased at higher concentrations. In addition, foliar electrolyte leakage and antioxidant defence activities increased linearly with increasing TCB concentration but were suppressed at higher concentrations in the roots. Taken together, the results support the hypothesis that antioxidant defence responses are an important component of plant responses to TCB, and oxidative damage appears to be a major factor leading to growth suppression in wheat exposed to higher TCB concentrations.