氮素形态对大豆铝毒和根表铝形态分布的影响

Effect of Nitrogen Forms on Aluminum Toxicity to Soybean( Glycine max) and Aluminum Speciation on Root Surface

铝毒是酸性土壤上作物生长的主要限制因素,虽然对铝毒已开展广泛研究,但铝毒与植物根表铝形态分布的关系还不清楚。以大豆(Glycine max)为研究对象,通过氮铝交替和氮铝共存2种处理方式的水培试验,研究了氮素形态对大豆铝毒的影响以及氮铝相互作用对根表铝形态分布的影响。结果表明,氮铝共存时,硝态氮体系中大豆根表吸附的各种形态铝含量均高于铵态氮体系。氮铝交替处理导致铝对大豆产生毒害,铝显著抑制大豆根伸长,降低大豆生物量,但在铵态氮和硝态氮体系中铝对大豆的毒害程度相近。无论是无铝对照还是有铝处理,硝态氮体系中大豆的生长情况均优于铵态氮体系。硝态氮处理还促进了大豆根系对K、Mg和Mn等元素的吸收。氮铝共存时,铵态氮可通过离子竞争作用缓解铝对大豆根系的毒害。

Al toxicity,being a major factor limiting plant growth in acid soils,has been investigated extensively,but little has been reported on relationship between Al toxicity and Al speciation on plant root surface. A hydroponic experiment,designed to have two treatments,alternation of N and Al,or both N and Al simultaneously,was carried out to explore effects of forms of nitrogen on Al toxicity to soybean（ Glycine max） and joint effect of N and Al on Al speciation on soybean root surface. Results show that the amount of Al ions adsorbed on soybean root surface was higher in the nitrate system than in the ammonium system when N and Al were added simultaneously. In the treatment of alternation,Al toxicity to soybean was observed,significantly inhibiting extension of soybean roots and reducing biomass of the plant,and did not differ much in extent between the ammonium system and the nitrate system. However,the growth of soybean was better in the nitrate system than in the ammonium system no matter whether in treatments with or without aluminum. Nitrate also enhanced the absorption of Mg,K,and Mn by soybean roots. Ammonium alleviated Al toxicity to soybean by competing for adsorption sites with Al when both N and Al were present in the solution.