不同白榆品系对滨海盐碱地的改良效果及盐分离子的分布与吸收

为揭示不同白榆(Ulmus pumila L.)品系对滨海盐碱地土壤盐分的改良作用及盐分离子在土壤-白榆系统中的分布与吸收特征,筛选适宜在滨海盐碱地造林的耐盐白榆品系,以中度盐渍化生境下4年生的6种白榆品系(1,5,28,30,46,105号)为试验材料,采用野外取样与室内测试相结合的方法,研究了Na+、K+、Ca2+、Mg2+等盐离子在土壤及白榆品系各器官(根、茎、叶)中的分布特征。结果表明:(1)白榆可降低滨海盐碱地土壤中盐离子及全盐含量,不同白榆品系较对照的土壤全盐含量降低了55.0%～63.1%,30号白榆降幅最大。(2)不同白榆品系将Na+、K+、Ca2+、Mg2+优先积累到叶中,且叶中维持较高的K+/Na+、Ca2+/Na+、Mg2+/Na+比值,不同白榆品系通过建立新的离子平衡以适应盐胁迫环境。(3)不同白榆品系的离子吸收选择性系数均为SK,NaSCa,NaSMg,Na,其对K+的吸收选择性大于对Ca2+、Mg2+吸收选择性;种内差异导致不同白榆品系对Na+、K+、Ca2+、Mg2+吸收选择能力不同,28号白榆根系对K+的吸收性最强,5号白榆根系对Ca2+、Mg2+的吸收性最强。

Improvement Effects of Different Ulmus Pumila Strains on Coastal Saline Alkali Soil and Distribution and Absorption of Salt Ions

In order to reveal the improvement effects of different Ulmus pumila strains on soil salt in coastal saline alkali land and the distribution and absorption characteristics of salt ions in the soil:Ulmus pumila system, and to select the salt tolerant Ulmus pumila strains for afforestation in coastal saline alkali soil, six species of Ulmus pumila (No.1, 5, 28, 30, 46, 105 respectively) with 4 years old under moderate saline habitat were taken as test materials. Through field sampling and lab analysis, the distribution characteristics of salt ions (Na⁺, K⁺, Ca²⁺, Mg²⁺) in roots, stems, leaves of Ulmus pumila and soils were analyzed. The results showed that:(1) Ulmus pumila could significantly reduce the total salt contents of coastal saline alkali land, and the salt contents under different Ulmus pumila strains were 55.0%~63.1% lower than that of the control, Ulmus pumila of No. 30 gave the biggest reduction. (2) All the Ulmus pumila accumulated Na⁺, K⁺, Ca²⁺ and Mg²⁺ preferentially in the leaves, and high K⁺/Na⁺, Ca²⁺/Na⁺ and Mg²⁺/Na⁺ ratios were maintained in leaves. Ulmus pumila could adapt to salt stress by establishing new ionic equilibrium. (3) The absorption selectivity coefficients for all different Ulmus pumila strains were S_K,Na > S_Ca,Na > S_Mg,Na. The absorption selectivity of K⁺ was greater than those of Ca²⁺ and Mg²⁺. Different Ulmus pumila strains had different absorption ability for Na⁺, K⁺, Ca²⁺ and Mg²⁺, among which No. 28 had the highest absorbency to K⁺, And No. 5 had the strongest absorbency to Ca²⁺ and Mg²⁺.