Se对小麦种子发芽与根伸长抑制的生态毒理效应

Eco-Toxicological Effects of Selenium on Inhibition of Seed Germinat ion andRoot Elongation of Wheat (Triticum aestium L.)

采用水培试验研究了Se对小麦发芽时的胁迫效应,并结合土培试验,研究比较了3种土壤(石灰土、红壤、黄棕壤)Se污染对小麦种子发芽率和根伸长的生态毒理效应。结果表明,Se在适量范围内(<0.5mg·L-1)对种子萌发过程中各生理指标有促进作用,高剂量(>5mg·L-1)时,对种子活力、α-淀粉酶及幼苗和根生长具有胁迫效应。对Se浓度与种子发芽各项指标抑制率相关分析,呈显著正相关。按EC25比较,根长抑制率>根干重抑制率>茎叶长抑制率>α-淀粉酶抑制率>发芽抑制率,Se污染对根生长抑制最为敏感。不同土壤对种子发芽率和根伸长的抑制率研究表明,Se对种子根伸长的抑制率远远大于发芽抑制率。Se对根伸长的抑制率随着土壤Se含量的增高而增大,两者呈极显著的正相关,根伸长抑制率可作为土壤污染的生物指示物。采用EC10计算得Se土壤临界值:石灰土为38.7mg·kg-1,黄棕壤为138mg·kg-1,红壤为182mg·kg-1。

We studied potential risk to ecosystem and eco-toxicology effects of Se on seed germination and root elongation of wheat (Triticum asetium L.) at our laboratory. Both aquatic and soil cultures were used to research physiologi cal and ecological responses of seed germination and root elongation with 10 con centrations of Se, i.e. 0, 0.1, 0.5, 1, 5, 10, 20, 40, 80, 150 mg·L-1, for t he former and Ten concentrations of Se, 0, 50, 100, 200, 300, 400, 500, 600, 800 ,1 000 mg·kg-1, used in three types of soils (calcareous, yellow-brown ear th, red earth soils) for the latter, respectively. For the inhibition of the ele ment on seed germination and root elongation of wheat, our results showed that l ow concentration of Se (under 0.5 mg·L-1) could promote the seed germination of wheat and its seedling growth, while high concentration of Se ( above 5 mg· L-1) reduces the germination rate of seed, the growth of seedling, its vigor and á-amylase activity markedly. The inhibition rates of Se on seed germinat ion physiological and ecological were significantly positive related with the co ncentrations of Se in the solution. The inhibition rates (IR) of various physiol ogical and ecological indexes were showed below according to an order of EC25 v alue: root length IR>root weight IR > stem &leaf length IR>á-amylase acti vity IR >germination IR, suggesting that the inhibition rate of root growth be a sensitive biomarker. The eco-toxicity effects of Se on the inhibition of see d germination and root elongation of wheat were tested in three types of soils i ndicated that the root elongation was much stronger than that on the seed germin ation with the same concentration of Se. In the soil test, the inhibition rate o f root elongation should strongly positive relation to the concentrations of Se. It was suggested that the inhibition rate of 25%( EC25) could be regard as a critical value in soil, and therefore a critical concentration of Se in soil we re estimated to be 38.7 mg·kg-1 in calcareous soil, 138 mg·kg-1 in yello w-brown earth, 182 mg·kg-1 in red earth soil, respectively.