不同生态型铺地黍在镉胁迫下的生长适应性

Growth adaptability and difference response among different ecotypes of torpedograss responding to Cd

摘要:

【目的】了解不同生态型铺地黍(Panicum repens)在污染河岸消涨带水淹条件下对镉胁迫的生长适应性和生理响应，筛选优异生态型铺地黍。【方法】选取 3 种生态型铺地黍(E‐dabaoshan、E‐ guangdong、E‐hainan)，利用水培试验模拟消涨带水淹环境，比较镉胁迫下不同生态型铺地黍的形态指标和生理指标。【结果】3 种生态型铺地黍完全能够耐受 12 mg/L 浓度的镉胁迫，植株存活率高达 70%~100%，但是分枝能力降低。E‐dabaoshan 在 12 mg/L 镉处理下的地上生物量分别达到 E‐guang‐ dong 和 E‐hainan 的 1. 76 和 1. 86 倍，其形态特征(分枝数、节间长、茎粗、植株高度和地上部生物量)均显著高于 E‐guangdong 和 E‐hainan(P＜0. 05)，表现出更强的表型可塑性。铺地黍过氧化物酶(POD)和过氧化氢酶(CAT)活性均受到抑制，叶绿素(Chl)含量降低，叶绿素受镉胁迫影响敏感度为 Chl a＞Chl a+b＞Chl b，但随胁迫时间延长，POD 和 CAT 活性抑制率减小，叶绿素含量逐渐增加。E‐dabaoshan 受抑制最小，镉胁迫 28 d 后，POD 和 CAT 活性与 CK 无显著差异，这与形态指标表现相符。【结论】 E‐ dabaoshan 能够逐渐修复镉伤害，有较高的镉耐受性。根据 3 种生态型铺地黍的表现，结合土壤生境条件，推断铺地黍原生境条件对镉胁迫的生长适应性影响较大。

Abstract:

It is very difficult for plants to grow in the polluted riparian flood zones due to the alternative changes of extreme drought and flooding. Torpedo grass (Panicum repens L.) has strong ability to tolerate to drought，flood and heavy metal，thus it can be used to improve the damaged riparian flood zones. In order to understand the adaptabil‐ ity and physiological response of torpedo grass to Cd stress under the condition of flooding，ecotypes of torpedo grass were screened. Hydroponics Experiments were conducted to simulate flooding environment in the riparian flood zones. Three ecotypes of torpedo grass collected from different habitats and regions were used to study its ecological adaptability and physiological responses to Cd stress. Three ecotypes including E ‐ dabaoshan (collected from Da‐ baoshan Tailings Land)，E ‐ guangdong (collected from Guangdong) and E ‐ hainan (collected from Hainan) could fully tolerate Cd stress at concentrations below 12 mg/L，and their plant survival rates were as high as 70%~100%. However，the ability of branching decreased compared with CK. The shoot biomass of E‐dabaoshan under Cd treat‐ ment (12 mg/L) was 1. 76 -1. 86 times of E‐guangdongand and E‐hainan，respectively. Their morphological charac‐ teristics，such as branches，internode length，stem diameter，plant height and shoot biomass，were significantly higher than those of E‐guangdong and E‐hainan (P＜0. 05)，showing stronger phenotypic plasticity. The activities of peroxi‐ dase (POD) and catalase (CAT) and chlorophyll content of torpedo grass were inhibited under the Cd stress. The sensitivity of chlorophyll affected by Cd showed the trend： Chl‐a＞Chl‐a+b＞Chl‐b in the early stage of Cd stress. But with the prolongation of stress time，the inhibition rate of the activity of POD and CAT and chlorophyll content decrease. E ‐ dabaoshan was least inhibited. There was no significant differences between the activity of POD and CAT of E‐dabaoshan and CK on the 28dth (P＞ 0. 05)，which is consistent with the performance of morphological in‐ dicators. The results suggest that E‐dabaoshan may gradually repair cadmium damage leading to high cadmium toler‐ ance. According to the performance of three ecotypes，combined with the soil habitat conditions，it implies that the original habitat conditions of torpedo grass have a greater impact on the adaptability of Cd stress.