四种耐盐牧草根际盐分动态分布特征

Dynamics of soil salt content in the rhizosphere soils of four salt-tolerant forage species

本试验以引大灌区永登县次生盐渍化土壤为背景,采用盆栽根袋法对4种耐盐牧草根际和非根际土壤pH和盐分离子的分布特征进行了研究。结果表明,随培养时间的延长,土壤pH、电导率和6种主要可溶性盐离子含量降低,4种耐盐牧草根际土壤pH值低于非根际土壤,差异显著(P<0.05)。培养90d后,4种牧草根际土壤电导率均高于非根际土壤。不同培养时段内,盐分离子在根际和非根际土壤中的分布呈动态变化;除培养90d的新疆大叶外,Ca2+和Mg2+在4种牧草的培养期内均在根际土壤出现富集;在培养60d时,田菁根际土壤中K+出现亏缺,但在随后的生长周期内则出现富集,而其他3种牧草培养期间在根际土壤中K+均出现亏缺;除培养90d的新疆大叶和中兰一号外,Na+和Cl-在4种耐盐牧草的培养期内在根际土壤中均出现富集。4种牧草在同一培养时间内,6种可溶性盐离子在根际与非根际土壤之间差异显著(P<0.05)。Na+/Ca2+和Na+/Mg2+降低,表明在大部分生长期间田箐、朝鲜碱茅、中兰一号3种耐盐牧草根际聚集的盐分为NaCl,新疆大叶为MgCl2和MgSO4。

A rhizobag experiment to investigate the dynamics of pH and salt ions in the rhizosphere and bulk soils was conducted on calcareous salt-affected soils using four salt-tolerant forage species in the Yin Da irrigation district,Yongdeng County of Gansu province.The pH,EC and concentrations of six major salt ions in the soils of tested forage species decreased with an extension of incubation time.There was a significantly lower pH in rhizosphere soils than in corresponding bulk soils during the growth period of all tested plants,such as Xinjiangdaye（Medicago sativa cv.Xinjiangdaye）,Zhonglan No.1（M.sativa cv.Zhonglan No.1）,Sesbania cannabina and Puccinellia chinampoensis.EC was higher in rhizosphere soils than in bulk soils for all tested plants after a 90-day growth period.The distribution of salt ions in the rhizosphere and bulk soils showed different change trends at different incubation times.Ca2＋ and Mg2＋ were enriched in the rhizosphere soils at different growth stages of all tested plants except Xinjiangdaye at the 90-day growth stage.At the 60-day growth stage,K＋ concentration in the rhizosphere soils of S.cannabina decreased,but then increased at subsequent growth stages.For the other three forage species,K＋ was in deficit in the rhizosphere soils.Na＋ and Cl-concentrations increased in the rhizosphere soils at different growth stages for all tested plants except Xinjiangdaye and Zhonglan No.1 at the 90-day growth stage.There were significant differences in six major salt ions between the rhizosphere and bulk soils for all tested plants at the same growth stage.The Na＋/Ca2＋ and Na＋/Mg2＋ showed a decreasing trend with an extension of incubation time.This indicated that the deficit of Na＋ in the soils was more profound than those of Ca2＋ and Mg2＋,and that Na2SO4 and MgSO4 were enriched in the rhizosphere soils of Xinjiangdaye,while NaCl was enriched in rhizosphere soils of the other three forage species.