黑土施镍对大豆幼苗生长的影响及镍中毒研究

为分析镍对大豆幼苗生长的影响及毒害作用,以黑土作为供试土壤,采用盆栽方法,研究了不同施镍水平下大豆幼苗的生长情况,并对大豆幼苗镍中毒临界值及中毒程度进行分析。结果表明:随着施镍量的增加,大豆植株鲜重、干重均呈先增加后降低的趋势。通过对土壤有效镍与大豆植株干重、土壤有效镍与植株含镍量进行拟合,推导出大豆幼苗生长状态最佳时的土壤有效镍含量为10.88 mg/kg,植株含镍量为26.46 mg/kg;中毒临界值(即某一施镍水平下的植株干物质累积量与不施镍处理相同)土壤有效镍为21.25 mg/kg,植株含镍量38.80 mg/kg;奢侈吸收区间黑土有效镍含量为10.88~21.25 mg/kg。以某一施镍水平下的干重占空白干重的90%~100%为轻度中毒分界点,得出大豆幼苗处于轻度中毒状态时的土壤有效镍含量为21.25~44.76mg/kg,此时植株镍含量为38.80~68.14mg/kg;促使大豆植株出现中度中毒时(干重为空白的80%~90%)的土壤有效镍含量为44.76~69.62mg/kg,此时植株镍含量为68.14~95.48 mg/kg;当土壤有效镍含量>69.62 mg/kg时,大豆植株则处于高度中毒状态(干重为空白的80%以下),此时植株含镍量>95.48 mg/kg。

Influence of Applied Ni on Soybean Seedlings Growth and Its Toxicity in Black Soil

In order to analyze the toxic effect of excessive nickel on the growth of soybean seedlings,pot incubation method was used to study the growth of soybean seedlings under different levels of applied nickel and the critical value and the degree of nickel toxicity of soybean seedlings which grew in black soil were analyzed.The results showed that the fresh and dry weight of soybean seedlings increased initially and then decreased with applied nickel increasing.The fitting equations of available nickel in soil and the dry weight,the concentration of nickel in soybean seedlings showed that available nickel in soil of 10.88 mg/kg made soybean seedlings grow best,and its corresponding concentration of nickel in plant was 26.46 mg/kg.The critical values of nickel toxicity for soybean seedlings were: available nickel in soil was 21.25 mg/kg and the concentration of nickel in plant was 38.80 mg/kg.Thus soybean′s luxury absorption for available nickel in soil was 10.88—21.25 mg/kg.Mild toxicity was defined by the point which the dry weight of applied nickel treatment was equal to 90%—100% of the blank treatment.Thus when mild toxicity of soybean seedlings appeared,the available nickel in soil was 21.25—44.76 mg/kg and the concentration of nickel in plant was 38.80—68.14 mg/kg.When toxicity was moderate(the dry weight being 80%—90% of the blank treatment),the available nickel in soil and plant was 44.76—69.62 mg/kg and 68.14—95.48 mg/kg respectively.When the available nickel in soil was more than 69.62 mg/kg,severe toxicity of the soybean seedlings appeared(the dry weight being less than 80% of the blank treatment) and its concentration of nickel was 95.48 mg/kg.