汞胁迫对水稻生长及幼苗生理生化的影响

Effects of Hg Stress on Growth and Physiological and Biochemical Characteristics of Rice Seedlings

通过水培试验,研究汞胁迫下水稻的生长指标包括株高、分蘖和根冠比的变化以及生理生化指标包括叶绿素含量、游离脯氨酸含量及SOD、POD、CAT保护酶活性的变化。结果表明,低浓度汞处理对水稻株高、穗重有促进作用,高浓度处理则显著降低株高和穗重;低浓度汞处理对水稻分蘖影响不明显,而10mg·L-1Hg2+显著降低分蘖数,且无效蘖、小、弱分蘖增多。汞胁迫下根冠比增加,汞对茎叶的抑制作用大于对根的影响。汞胁迫下CAT、POD活性总体上变化不明显,但均在10mg·L-1Hg2+时达到较高值。汞胁迫对叶片相对含水量及脯氨酸含量的影响不显著。不同浓度处理的叶绿素b、类胡萝卜素的含量与对照相比均不显著。而叶绿素a和叶绿素a+b在低浓度处理时其含量均高于对照,高浓度对叶绿素a起到抑制作用。

The hydroponics was adopted in our experiments to research the effects of heavy metal Hg on the growth characteristics, including plant height, tiller, the ratio of root/shoot and the physiological and biochemical characteristics including the content of chlorophyll and free proline and the activity of protective enzyme SOD, POD and CAT. The results showed that at low concentrations of Hg, the height and the ear weight of paddy were promoted but restrained significantly at 10 mg·L^-1 and 50 mg·L^-1 Hg^2＋. The tiller number of rice showed no obvious reduction at lower concentration of Hg^2＋, but reduced significantly at 10 mg·L^-1 and 50 mg·L^-1 Hg^2＋ as well as small and weak tillers increased. Under cadium stress, the ratio of root/shoot increased, indicating the restrain effect of cadium on shoot was greater than that of root in rice. There was no significant difference in content of chlorophyll b and pigment of carotenoid between Hg^2＋ stress and the control, but, with Hg2^＋ concentration increasing, the content of chlorophyll and biomass dropped obviously. In addition, Hg^2＋ could induce the protective enzyme activity. Hg^2＋ showed no significant effect on relative water content of leaves and the content of free proline.