镉胁迫下福美双对小麦幼苗镉积累及生理特征的影响

为探明Cd胁迫下喷施杀菌剂福美双对小麦幼苗Cd积累及生理特征的影响,本研究以常规冬小麦品种为供试作物,采用水培法,在不同浓度Cd胁迫下,于小麦苗期分别喷施高（400倍稀释液）、低（800倍稀释液）两个剂量的福美双制剂,研究福美双对小麦幼苗Cd积累、分布以及抗氧化系统和光合作用等生理特征的影响。结果显示：在Cd积累方面,施用福美双提高了小麦地上部Cd和S的含量,最高增幅分别为73.8%和151.2%。同一Cd浓度胁迫下,随着福美双施用剂量的提高,Cd在小麦亚细胞各器官中的含量增加,在细胞壁中的占比升高,在细胞可溶性组份中的占比减少; Cd由氯化钠提取态向乙醇提取态和水提取态转变。喷施福美双对麦苗地上部鲜质量和根系长度无显著影响。在光合作用方面,Cd胁迫下喷施福美双提高了小麦叶片光合速率、叶绿素a和叶绿素b含量,最高增幅分别为62.7%、36.0%和89.5%。在抗氧化作用方面,Cd胁迫下喷施福美双提高了小麦叶片MDA、H₂O₂和CAT含量,最高增幅分别为27.1%、123.6%和464.3%; SOD含量下降,最大降幅为20.1%。研究表明,施用福美双促进了小麦幼苗地上部Cd积累,提高了植株的光合作用,但降低了植株的抗氧化能力并加剧了Cd胁迫,高剂量条件下的施药效应更加显著,建议在镉污染麦田防治病害尽量不施用或少施用福美双。

Effects of thiram on Cd accumulation and physiological characteristics of wheat seedlings under Cd stress

To investigate the effects of thiram on the cadmium(Cd)accumulation and physiological characteristics of wheat seedlings under Cd stress, this study used a conventional winter wheat variety as the test crop and conducted a hydroponics experiment. High(400-times dilution) and low(800-times dilution)thiram dosages were sprayed on wheat seedlings under stress caused by different concentrations of Cd to study the effects of thiram on Cd accumulation and distribution and physiological characteristics such as photosynthesis and the antioxidant system. The results indicated that applying thiram increased the accumulation of Cd and S in the wheat shoots. The highest increases were 73.8% for Cd and 151.2% for S. Under Cd stress with the same Cd concentration, as the thiram dosage increased, the Cd content in the various subcellular organs of wheat increased. A higher proportion of Cd was found in the cell wall, and a lower proportion was observed in the cell-soluble components. Furthermore, Cd shifted from being extractable by chloride to be extractable by ethanol and water. The foliar application of thiram did not significantly affect the fresh weight of the wheat seedling shoots or the root length. However, in terms of photosynthesis, under Cd stress, the foliar application of thiram increased the photosynthetic rate and the contents of chlorophyll a and chlorophyll b in wheat leaves; the highest increases were 62.7%, 36.0%, and 89.5%, respectively. Regarding antioxidant activity, under Cd stress, the foliar application of thiram increased the contents of MDA, H₂O₂, and CAT in wheat leaves; the highest increases were 27.1%, 123.6%, and 464.3%, respectively. However, the SOD content decreased, with a maximum decrease of 20.1%. The findings indicated that thiram application promoted Cd accumulation in wheat seedlings and improved the photosynthesis of plants; however, it decreased the antioxidant capacity of the plants and aggravated Cd stress. The effect of thiram application under high-dose conditions was stronger. This finding provides useful information for studying the effects of pesticides on Cd accumulation in crops and the physiological characteristics of Cd stress. Thiram application should be avoided or minimized as much as possible to control diseases in Cd-polluted wheat fields.