Abstract:

The effects of cadmium stress on Avena fatua seedlings and accumulation property were studied with 1/2 MS nutrient solution culture experiments. The results showed that Cd stress could stimulate the growth of A. fatua seedlings at low level Cd²⁺ concentration (0.6 mg·L^-1, 2 mg·L^-1 and 8 mg·L^-1). Plant height, leaf length, root length and stem diameter were improved at low Cd²⁺ concentrations, whereas plant growth was inhibited at high Cd²⁺ concentrations (15 mg·L^-1 and 30 mg·L^-1). And the low level of Cd²⁺ concentration could help plant to accumulate fresh weight in shoot and in root as well as dry weight in shoot and in root. With the increase of Cd²⁺ concentrations, plant cell membrane permeability, the free proline contents of above-and under-ground increased gradually; the activities of SOD and POD firstly increased then decreased. It concluded that A. fatua was suitable for the remediation of Cd polluted soil when Cd²⁺ concentration was less than 8 mg·L^-1. Principal component analysis showed that the underground dry weight of seedling had the highest loading score at the first principal component, indicating this factor was effective to reflect the growth state of Avena fatua seedling under Cd stress.

Key words: Avena fatua, Cadmium stress, Seedling growth, Physiological characteristics, Principal component analysis

摘要：

为了解植物幼苗对金属镉(Cd)的反应,以野燕麦(Avena fatua)幼苗为材料,采用1/2 MS营养液水培试验,研究野燕麦幼苗对不同Cd²⁺浓度胁迫的反应积累特性。结果表明:低浓度的Cd²⁺(0.6,2,8 mg·L^-1)能够促进野燕麦幼苗生长,具体表现在促进植物株高、叶长、根长、茎粗的增加,地上、地下部分干、鲜重量的积累;高浓度Cd²⁺(15,30 mg·L^-1)抑制野燕麦幼苗生长,各项生长指标在该浓度下都显示不同程度的降低;随Cd²⁺胁迫浓度的升高,野燕麦叶片细胞膜透性、植株地上、地下部分游离脯氨酸含量大量积累;超氧化物歧化酶和过氧化物酶都呈先升后降的趋势,至Cd²⁺浓度为8 mg·L^-1时达到最大值,随后在Cd²⁺浓度为15 mg·L^-1时,表现为活性下降。表明野燕麦适用于浓度小于8 mg·L^-1 Cd²⁺污染土壤的修复。主成分分析结果表明,在第一主成分上野燕麦幼苗地下干重具有最高的载荷,说明地下干重可以很好的反映镉胁迫下野燕麦幼苗的生长状态。

关键词: 野燕麦, 镉胁迫, 生长指标, 生理响应