砷对小麦苗期生长的影响及降低砷毒性的措施

Effects of arsenic on wheat seedling growth and corresponding agronomic measures for toxicity mitigation

为探讨砷(As)污染对小麦苗期生长的影响,并提出减缓As毒害的农艺措施,以两个品种小麦作为供试材料,通过水培试验研究小麦苗期根系、茎叶对As(Ⅲ)吸收、累积的差异,以及As(Ⅲ)对小麦的毒性效应,采用盆栽试验研究硅(Si)肥、磷(P)肥施加对小麦根系、茎叶生物量及As含量的影响。结果表明:晋麦1号和晋麦2号根系生物量的As(Ⅲ)半数抑制浓度分别为1.2μmol·L^(-1)和2.2μmol·L^(-1),晋麦1号受As(Ⅲ)毒害引起的生理氧化胁迫显著,而晋麦2号根系受As(Ⅲ)毒害症状较弱;相较于晋麦1号,晋麦2号根系会吸收更多的As并向地上部分转运,对人体健康具有潜在危害。此外,Si、P肥的添加不仅有效增加了小麦根系、茎叶的生物量,而且显著降低了根系、茎叶中As的含量,200 mg·kg^(-1) Si肥添加后,根系、茎叶中As含量分别降低了77.4%和60.5%,100 mg·kg^(-1) P肥添加后,根系、茎叶中As含量分别降低了67.6%和49.2%。研究表明,两种小麦吸收、转运和累积As的能力不同,受As毒害产生的氧化胁迫也不同,小麦品种间As耐性存在差异;施加Si、P肥有利于降低小麦各组织部位As的含量。

In this study,the absorption and accumulation abilities of roots and shoots and the toxic effects of arsenic(As)on wheat seedlings(Triticum aestivum L.)were explored to evaluate the influence of As pollution.In addition,related toxicity mitigation agronomic measures were proposed.Two varieties of wheat(Jinmai No.1 and Jinmai No.2)were selected as test plants,and the hydroponic method was used in a part of the experiment.Silicate(Si)and phosphate(P)fertilizers were applied separately to study the differences in root and shoot biomass and As accumulation.The semi-inhibitory concentration of As(Ⅲ)in the root biomass for Jinmai No.1 and No.2 were 1.2μmol·L^(-1) and 2.2μmol·L^(-1),respectively.The physiological oxidative stress caused by As(Ⅲ)was more significant in Jinmai No.1 than in Jinmai No.2.As(Ⅲ)showed no obvious toxicity.Compared to that in Jinmai No.1,more As was absorbed in the roots and shoots and transported to the aboveground foliage of Jinmai No.2,which indicates a higher human health risk.In addition,the application of Si and P effectively increased the biomass of roots and shoots and led to a significant reduction in As accumulation in the roots and shoots.Accumulated concentrations of As in the roots and shoots of wheat seedlings decreased by 77.4% and 60.5%,and 67.6% and 49.2% for the 200 mg·kg^(-1) Si and 100 mg·kg^(-1) P addition groups,respectively.Therefore,the absorption,transportation,and accumulation abilities of As and the oxidative stress caused by As differ between the two wheat varieties,and there are differences in the arsenic tolerance between the two wheat seedlings.The application of Si and P is an effective agronomic practice for reducing As concentration in various tissues of wheat.