摘要:为探究干旱和重金属双重胁迫对土壤-小麦-蚜虫系统内Cd转移规律的影响，为小麦蚜虫的生态调节提供理论依据，本研究以麦长管蚜[Sitobion avenae（Fabricius）]为研究对象，用原子吸收分光光度法分别测定不同土壤Cd含量（100 mg·kg-1、200 mg·kg-1）及不同程度干旱胁迫（无胁迫、中度胁迫、重度胁迫）处理下小麦根茎叶及蚜虫体内的Cd含量。结果表明：土壤Cd含量及干旱单一胁迫均对小麦及蚜虫体内的Cd含量造成了显著影响（P < 0.05）。两者交互作用对小麦根部及叶部的Cd含量影响显著，而对小麦茎部及蚜虫体内Cd含量影响不显著。在相同胁迫条件下，Cd在小麦中的积累分布为根>茎>叶。随着干旱胁迫程度增大，小麦根部Cd含量及土壤-根转移系数降低，茎部Cd含量及根-茎转移系数升高，麦长管蚜Cd含量在土壤Cd含量100 mg·kg-1下高于土壤Cd含量200 mg·kg-1；中度干旱胁迫增加了麦长管蚜体内Cd累积量，而重度干旱胁迫则降低了其体内Cd累积量。叶-蚜虫的Cd转移系数明显大于土壤-根、根-茎和茎-叶转移系数且大于1，说明Cd在麦长管蚜体内产生了生物富集作用。综上所述，干旱胁迫促进了Cd从土壤向小麦茎部转移和根部Cd累积，但抑制了Cd从根部到茎部转移和茎部Cd累积；中度干旱胁迫促进了麦长管蚜体内Cd的积累，而重度干旱胁迫抑制了麦长管蚜体内Cd的积累。
关键词:干旱/
Cd污染/
双重胁迫/
小麦/
麦长管蚜/
土壤-小麦-蚜虫系统
Abstract:There have been several reports regarding the effects of both drought and heavy metals on aphids. However, although aphids often experience dual stresses and even multiple stresses, such as a combination of heavy metals, drought, and other stress factors, in the natural environment, there have been few reports on dual or multiple stresses. To explore the effects of dual stresses from drought and heavy metal on the Cd transfer in the soil-wheat-aphid system, this study took Sitobion avenae (Fabricius) as the research object and used an atomic absorption spectrophotometer to measure the Cd contents of S. avenae and of the roots and leaves of wheat following treatment with different soil contents of heavy metals (100 and 200 mg·kg-1) and exposure to different degrees of drought stress (well-watered, moderate drought stress and severe drought stress). The results revealed that both soil Cd content and drought stress had significant effects on the Cd contents of both wheat and aphids (P < 0.05). The interactive effect of soil Cd content and drought stress was significant (P < 0.05) on Cd content of wheat roots and leaves, but it was not significant (P > 0.05) on Cd content of wheat stems and aphids. Cd accumulation in wheat was in the order of root > stem > leaves, under the same stress conditions. As drought stress increased, the Cd content of wheat roots and the Cd transfer coefficient from soil to roots gradually decreased, and the stem Cd content and transfer coefficient from roots to stems gradually increased. In S. avenae, the Cd content under 100 mg·kg-1 soil Cd content was higher than that under 200 mg·kg-1. Moderate drought stress increased Cd accumulation in the bodies of the aphids, whereas severe drought stress reduced the Cd accumulation. The Cd transfer coefficient from leaf to aphid was >1, and significantly larger than that from soil to root and that from root to stem and stem to leaf, indicating biomagnification of Cd in the aphids. In summary, drought stress promotes the transfer of Cd from soil to stems of wheat and its accumulation in roots, but it inhibits the transfer of Cd from root to stem and its accumulation in stem. Moderate drought stress promotes Cd accumulation in S. avenae, whereas severe drought stress inhibits Cd accumulation in aphid.
Key words:Drought stress/
Cd pollution/
Dual stress/
Wheat/
Sitobion avenae (Fabricius)/
Soil-wheat-aphid ecosystem
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