采用水培法研究了不同浓度 Pb 胁迫对马蔺〔Iris lactea Pall. var. chinensis (Fisch.) Koidz.〕种子萌发及根尖细胞有丝分裂的影响。 结果显示,在500 ~ 1 500 mg· L ^{- 1}浓度范围内,随 Pb 浓度的提高,马蔺种子的发芽势、发芽率、发芽指数、活力指数及幼苗根尖细胞有丝分裂指数均呈现出逐渐降低的趋势。 经500、1 000 和1 500 mg· L ^{- 1} Pb 胁迫处理后,种子发芽势分别仅为对照的 52. 8% 、51. 3% 和 47. 2% ,种子发芽率分别仅为对照的 55. 8% 、54. 3% 和46. 5% , 种子发芽指数分别比对照降低了 55. 1% 、 56. 7% 和 57. 8% , 种子活力指数分别比对照降低了 65. 4% 、72. 0% 和 79. 2% ,幼苗根尖细胞有丝分裂指数分别降至对照的 28. 1% 、21. 9% 和 13. 5% ,且各处理组各指标与对照的差异均达到显著水平(P < 0. 05),但各处理组间的种子发芽势、发芽率、发芽指数及幼苗根尖细胞有丝分裂指数差异均不显著。 研究结果表明,Pb 胁迫对马蔺种子萌发及幼苗根尖有丝分裂有显著抑制作用,但马蔺种子萌发和幼苗根尖有丝分裂对浓度高于 500 mg· L ^{- 1}的 Pb 胁迫反应不敏感。

 

The effects of Pb stress with different concentrations on seed germination and root-tip cell mitosis of Iris lactea Pall. var. chinensis ( Fisch.) Koidz. were studied by water culture method. The results show that within 500 - 1 500 mg· L - 1 Pb, the seed germination energy, seed germination rate, seed germination index, seed vigor index and root-tip cell mitosis index of seedling of I. lactea var. chinensis decrease gradually with the increase of Pb concentration. Under 500, 1 000 and 1 500 mg· L ^{– 1} Pb stress condition, the seed germination energy of I. lactea var. chinensis is 52. 8% , 51. 3% and 47. 2% of that of the control. The seed germination rate is 55. 8% , 54. 3% and 46. 5% of that of the control. The seed germination index decreases 55. 1% , 56. 7% and 57. 8% compared to the control. The seed vigor index decreases 65. 4% , 72. 0% and 79. 2% compared to the control. And the root-tip cell mitosis index is only 28. 1% , 21. 9% and 13. 5% of that of the control. There are significant differences between the indexes of treatment groups and the control (P < 0. 05), but the indexes among treatment groups are not significantly different except the seed vigor index. It can be concluded that the seed germination and root-tip cell mitosis of I. lactea var. chinensis are inhibited obviously under Pb stress, but they are not sensitive to the stress when the concentration of Pb is higher than 500 mg· L ^{- 1}.