A soil culture experiment was conducted to study the effects of 1,2,4-trichlorobenzene (TCB) on morphological and physiological indexes of rice at top tillering stage, using rice cultivars of Ningjing 1 (TCB sensitive genotype) and Yangfujing 8 (TCB tolerant genotype), with four treatments of TCB concentrations including 0 (CK), 20, 40 and 60 mg kg-1. The results indicated that the maximum root length, plant height, tillers per hill, shoot and root dry weight of Ningjing 1 were all decreased significantly (P<0.05) under different concentrations of TCB. Low TCB stress (20 mg kg-1) significantly increased Yangfujing 8’s maximum root length, shoot and root dry weight , root activity (P<0.01), while medium and high TCB stresses (40 and 60 mg kg-1) decreased maximum root length, plant height, tillers per hill, shoot and root dry weight significantly(P<0.05). Ningjing 1’s root activity, chlorophyll content, soluble protein content in leaves and roots were relatively low under different concentrations of TCB, at the same time, its activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) in leaves and roots decreased, while O2? producing velocity and malnodialdehyde (MDA) content increased significantly (P<0.05). Low TCB stress (20 mg kg-1) significantly increased Yangfujing 8’s soluble protein content and activities of SOD, POD, CAT in leaves and roots, and significantly (P<0.05) decreased its O2? producing velocity and MDA content. Under medium TCB stress (40 mg kg-1), the activities of SOD, POD, CAT in leaves and roots were enhanced, however, its O2? producing velocity and MDA content increased significantly. High TCB stress (60 mg kg-1) decreased its root activity, chlorophyll content, the activities of SOD, POD, CAT in leaves and roots, and increased O2? producing velocity and MDA content significantly (P<0.05). In a word, compared with sensitive genotype, well growth vigor, high protein content in leaves and roots, better ability of antioxidant system in scavenging reactive oxygen speciesand lower membrane lipid peroxidation under low concentration TCB stress (20 mg kg-1) are regarded as the main features of TCB tolerant genotype in rice.
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