酸雨胁迫下La(Ⅲ)对水稻种子萌发及POD活性影响

Effect of Lanthanum on the Germination of Rice Seeds and POD Activity Under Acid Rain Stress

为揭示酸雨影响种子萌发机理及减轻酸雨抑制种子萌发的途径,以pH2.0、2.5、3.0、3.5、4.0、4.5、5.0模拟酸雨溶液和稀土La(Ⅲ)复合处理水稻种子,探讨La(Ⅲ)对酸雨胁迫下水稻种子萌发、过氧化物酶(POD)活性和可溶性蛋白含量的影响。结果表明,高强度酸雨(pH≤2.5)胁迫下,经La(Ⅲ)处理和单一酸雨处理的水稻种子萌发均受到不可逆转性伤害:发芽率、发芽势、发芽指数、活力指数皆为零,部分种子异状发芽,POD活性及可溶性蛋白含量显著下降,La(Ⅲ)对种子的防护作用不明显。酸雨强度在pH≥3.0时,经La(Ⅲ)处理种子各项指标均高于单一酸雨处理种子,且指标变化曲线的拐点向酸度加大的地方推进,加强了种子对pH的耐受限度,说明La(Ⅲ)在缓解酸雨对水稻种子的伤害过程中具有重要意义。

The effect of lanthanum on rice （Oryza. Sativa） seed germination under acid rain stress was investigated to reveal the mechanism of seed germination and the way of alleviating the seed germination inhibition by acid rain. Rice seeds soaked with LaCl3 solution （0.5, 1, 5, 10, 15, 20 and 30 mg·L^-1） were placed in culture dishes with filter sheets to germinate in a culture container kept at constant temperature of 30 ℃, in which each treatment involved three dishes and each dish received 30 seeds, and the germination percentage, germination energy, germination index and vigor index were determined. After soaked with 1 mg·L^-1, the germination indexes of rice seeds were the highest. So, rice seeds after soaked with 1 mg· L^-1 LaCl3 solution were exposed to simulated acid rain pH 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, pH6.5 as the control group （CK） that was replaced everyday. Seed germination, activity of peroxidase and content of soluble protein were investigated. The results showed that the rice seed germination was irreversibly inhibited by acid rain and La（Ⅲ）＋acid rain under severe acid rain stress （pH ≤ 2.5）, and germination percentage, germination energy, germination index, vigor index were all zero, some seeds were abnormally germinated, both the POD activity and soluble protein content were obviously decreased, indicating that the protective effect of La（Ⅲ） was not obvious. At pH ≥ 3.0, the above indexes of seeds pretreated with La（Ⅲ） were higher than those of acid rain group, strengthening the tolerance of seed germination to pH, suggesting that lanthanum could alleviate the damage of acid rain to rice seed germination.