硒元素对铅、汞胁迫下紫花苜蓿生长的影响

Effects of Selenium on Alfalfa Growth,Nutrient Absorption and Nitrogen Fixing Ability under Pb and Hg Stress

采用沙培盆栽的方法,探讨了在重金属铅、汞胁迫下硒元素对紫花苜蓿生长、养分含量及固氮能力的影响,结果显示:浓度为5mg/kg的硒能明显促进紫花苜蓿的生长,单株干重、粗蛋白含量分别比对照增加了19.8%、12.9%,茎叶硒含量为4.19mg/kg,根瘤固氮酶活性提高了28.7%;单施铅浓度为500mg/kg时,植株干草产量比对照下降了25.3%,过氧化物酶(POD)活性提高了23.2%,茎叶铅含量增加了104.2%,粗脂肪含量下降了31.1%;单施汞浓度为1.5mg/kg时,植株干草产量下降了36.1%,茎叶汞含量增加了256.0%,脯氨酸(Pro)含量增加了15.8%,固氮酶活性下降了51.5%;与铅、汞单施相比硒铅、硒汞混施植株茎叶铅、汞含量分别降低了40.5%和47.9%,Pro含量分别下降了10.9%、6.7%,POD活性下降了7.8%、9.13%,固氮酶活性增加了6.58%、13.1%。适宜浓度的硒元素对紫花苜蓿的促生作用明显,同时能缓解重金属铅、汞对植株生长的毒害。

A sand pot experiment was adopted to study the effects of applying selenium fertilizer on the growth,nutrient absorption and nitrogen fixing ability of alfalfa under Pb and Hg stress.The results showed that Se in concentration of 5 mg/kg obviously promoted the growth of alfalfa dry weight,crude protein content and nitrogenase activity by 19.8%,12.9% and 28.7%.Contents of Se in shoots was 4.19mg/kg.Treating withρ（Pb）=500mg/kg alone dry weight and crude fat decreased by 25.3%and 31.1%,POD activity and contents of Pb in shoots increased by 23.2% and 104.2%.Treating withρ（Hg）=1.5mg/kg alone dry weight and nitrogen fixing ability decreased by 36.1% and 51.5%,contents of Hg and Pro in stem and leaf increased by 256.0%and 15.8%.Compared with applying Pb and Hg alone,applying Se mixed with Pb,content of Pb and Hg in shoots decreased by 40.5% and 47.9%,Pro contents decreased by 10.9%,6.7%,and POD activity decreased by 7.8%、9.13%,nitrogenase activity increased by 6.58% and 13.1%.In conclusion,suitable concentration of Se not only promoted growth but also alleviate toxicity of Pb and Hg to alfalfa.