不同基因型水稻苗期对1，2，4-三氯苯胁迫的生理响应

利用沙培试验，研究了6种浓度(0、0.1、0.2、0.4、0.6、0.8 mmol kg^-1沙)的1,2,4-三氯苯(TCB)对两水稻品种香粳20-18(耐性基因型)和泗阳1382(敏感基因型)种子发芽率、发芽指数、幼苗生物量以及叶片和根系的蛋白质含量、丙二醛含量(MDA)、超氧化物歧化酶(SOD)活性、过氧化物酶(POD)活性、过氧化氢酶(CAT)活性等生理指标的影响。结果表明，TCB胁迫下，水稻种子发芽率和发芽指数变化不明显，幼苗的生物量显著下降，香粳20-18下降幅度比泗阳1382小；随TCB胁迫程度的增强，香粳20-18叶片和根系可溶性蛋白质含量呈增加的趋势，泗阳1382叶片蛋白质含量显著下降，高浓度TCB胁迫下其根系蛋白质含量显著下降；两个基因型叶片的O₂^?产生速率先降后升，香粳20-18根系的O₂^?产生速率先降后升，高浓度TCB胁迫下显著高于对照，而泗阳1382与对照差异不显著；香粳20-18叶片SOD活性随TCB胁迫程度的增强呈上升趋势，低浓度TCB胁迫下就开始显著高于对照，根系SOD活性显著增强，而泗阳1382叶片和根系SOD活性与对照差异不显著；香粳20-18叶片POD活性先升后降，根系POD活性显著高于对照，而泗阳1382叶片和根系POD活性均显著下降；香粳20-18叶片CAT活性高于或显著高于对照，泗阳1382低于或显著低于对照；两个基因型叶片的MDA含量先降后升，高浓度TCB胁迫下MDA含量显著高于对照，根系MDA含量均随TCB胁迫程度的增强而显著增加。总之，生物量降低幅度小、叶片和根系的蛋白质含量高、抗氧化酶系统清除活性氧的能力强、MDA含量低是耐性基因型的主要生理特征。

Physiological Response to 1,2,4-Trichlorobenzene Stress of Different Rice Genotypes in Seedlings

1,2,4-Trichlorobenzene (TCB) has pervaded in industrial and agricultural production. Because of a series of problems due to its longevity and amassment, TCB has been added into the environmental pollutant list. In order to know how TCB affects the rice seed germination, seedling growth and its physiological characteristics, the seed germination, seedling biomass, soluble protein, and malnodialdehyde (MDA) contents, as well as activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) in leaves and roots of seedlings treated with TCB were investigated in a sand culture experiment using rice cultivars, Xiangjing 20-18 (TCB tolerant genotype)and Siyang 1382(TCB sensitive genotype). The results indicated that TCB had little effect on the seed germination rate and index, however caused the significant reduction of seedling biomass, withXiangjing 20-18 being more affected than Siyang 1382. With TCB stress degree strengthening, soluble protein content of Xiangjing 20-18 leaves and roots presented anincreasing tendency, while that of Siyang 1382 leaves decreased significantly, and that of its roots decreased too under treatment of high TCB concentration. O₂^? producing velocity of leaves in two genotypes decreased firstly, then increased with increasing TCB concentration. That of Xiangjing 20-18 roots presented thesame tendency, and significantly higher than the control at TCB ≥0.6 mmol kg^-1, while that of Siyang 1382 roots had no significant difference with that of the control. SOD activity of Xiangjing 20-18 leaves increased, and that of roots increased significantly. After TCB ≥0.2 mmol kg^-1, SOD activity of Xiangjing 20-18 leaves was significantly higher than that of the control, that of Siyang 1382 leaves and roots was not significantly different with that of the control. POD activity of Xiangjing 20-18 leaves increased firstly, then decreased, and that of roots was significantly higher than the control, while that of Siyang 1382 leaves and roots decreased significantly. CAT activity of Xiangjing 20-18 leaves was higher or significantly higher than that of the control, and that of Siyang 1382 was contrary to the result of Xiangjing 20-18. MDA content of leaves decreased firstly, then increased, being significantly higher than that of the control at high TCB concentration, and that of roots increased significantly in two genotype. In conclusion, lower reduction of seedling biomass, high protein content of leaves and roots, the better active oxygen’s elimination ability and lower MDA content in plants would be considered as the physiological traits in TCB-tolerant genotypes of rice.