NaCl处理对西伯利亚白刺幼苗生长及离子平衡的影响

以1年生西伯利亚白刺水培幼苗为材料,研究了不同浓度NaCl(0、200、400mmol·L~(-1))处理对幼苗生长及不同器官(根、茎、叶)中Na~+、K~+、Ca~(2+)、Mg~(2+)的吸收、运输与分配的影响,探讨西伯利亚白刺的盐适应机制。结果表明:(1)200mmol·L~(-1) NaCl处理促进了西伯利亚白刺幼苗的生长及叶片肉质化程度,400mmol·L-1 NaCl处理显著抑制其生长。(2)随着NaCl处理浓度的升高,西伯利亚白刺幼苗根、茎、叶中Na~+含量显著增加,且叶中Na~+含量显著高于茎和根中;根系中K~+含量显著增加;根、茎、叶中Ca~(2+)、Mg~(2+)含量在200mmol·L~(-1) NaCl处理下保持平稳或上升,而在400mmol·L-1 NaCl处理下显著下降。(3)各器官中K~+/Na~+、Ca~(2+)/Na~+和Mg~(2+)/Na~+比值总体随NaCl处理浓度的升高呈下降趋势,且根部离子比值始终高于叶片和茎。(4)随着NaCl处理浓度的升高,西伯利亚白刺幼苗根-茎SK,Na显著下降,而根-茎SCa,Na、SMg,Na及茎-叶SK,Na、SCa,Na、SMg,Na逐渐提高。研究发现,西伯利亚白刺的盐适应机制主要是通过植株的补偿生长效应及叶片对Na~+的聚积作用实现的,同时也与根系对K~+的扣留及茎叶对K~+、Ca~(2+)、Mg~(2+)选择性运输能力增强有关。

Effect of NaCl Treatment on Growth and Ion Homeostasis of Nitraria sibirica Seedlings

To understand the salt tolerance mechanism of Nitraria sibirica seedlings under NaCl treatment, we investigated the growth of one year old N. sibirica seedlings and cationic absorption and distribution in different organs (such as roots, stems and leaves) under different levels of NaCl (0, 200 and 400 mmol·L^-1) treatment through hydroponic experiment in greenhouse. The results showed that: (1) the N. sibirica seedlings growth and succulent degree of leaves were significantly increased by 200 mmol·L^-1 NaCl treatment compared with control, but that were inhibited by 400 mmol·L^-1 NaCl treatment. (2) With the increase of NaCl concentration, the Na⁺ content in the roots, stems and leaves of the N. sibirica seedlings were significantly increased compared with those of the control seedlings, and the Na⁺ content in the leaves was significantly higher than that in stems and roots; The content of K⁺ in roots was significantly increased with the increase of NaCl concentration; The contents of Ca²⁺ and Mg²⁺ in roots, stems and leaves were stay steady or rise under 200 mmol·L^-1 NaCl treatment whereas decreased under 400 mmol·L^-1 NaCl treatment. (3) With the increase of NaCl concentration, the K⁺/Na⁺, Ca²⁺/Na⁺, Mg²⁺/Na⁺ ratios in different organs of seedlings were decreased, and the ratio of roots was always higher than that of stems and leaves. (4) The ability of K⁺ transporting from roots to stems was significantly decreased whereas the abilities of Ca²⁺, Mg²⁺ transporting from roots to stems and the abilities of K⁺, Ca²⁺ and Mg²⁺ transporting from stems to leaves were decreased under NaCl treatment. In conclusion, our findings suggested that the salt adaptation mechanism of N. sibirica seedlings were primarily implemented by plant compensation growth effect, leaf Na⁺ accumulation, also correlated with the ability of root arrest K⁺ and increased abilities of K⁺, Ca²⁺ and Mg²⁺ selective transportation in stems and leaves.