囊果碱蓬离子含量及分布特点

为研究真盐生植物矿质营养特征，以北疆荒漠囊果碱蓬群落为对象，通过土壤及植株调查，分析其矿质元素特征。结果显示：（1）囊果碱蓬的生长增加了0~30cm土壤的pH值、水分及盐份含量，并使盐分在土层重新分布。（2）根系相对于土壤，具有优先吸收K⁺、Mg²⁺ 养分离子的特点；叶片相对于根系，具有优先运输Cl^-、Na⁺、SO₄^2- 盐分离子的特点，同一离子在吸收和运输的选择不一致，与其在整株的功能相关。（3）Cl^-、Na⁺、SO₄^2- 积累于叶片，含量远大于K⁺、Mg²⁺、Ca²⁺ ，Cl^- 和Na⁺ 可能相伴向上运输，K⁺、Ca²⁺、Mg²⁺ 在根、茎、叶保持基本不变的比例。（4）囊果碱蓬属于SO₄ -Cl 盐积累植物，而背景土壤为Cl-SO₄ 型盐土。

Ion content and distribution in Suaeda physophora

Suaeda physophora is a leaf-succulent euhalophytic shrub with tall plant height and high biomass in northern Xinjiang, China. Its content and distribution of mineral elements can reflect the ability of halophytes to absorb soil moisture and mineral nutrients. In this study, soil and plant salinity and mineral nutrients were analyzed in S. physophora communities in a saline desert area in northern Xinjiang. The results were summarized as follows:(1)pH and moisture content in the 0-30 cm root zone soil increased with the growth of S. physophora. Moreover, the content of Na⁺, Cl^- and SO₄^2- and total salt content in the soil root zone significantly increased(P ≤ 0.05), leading to redistribution of soil salinity.(2)The highest ion content was measured in leaves, while a low ion content was detected in roots and stems.(3)The contents of Cl^-, Na⁺ and SO₄² was 11.9%, 11.7%, and 3.3%, respectively, which were much higher than those of K⁺, Mg²⁺ and Ca²⁺. The distributions of Cl^-, Na⁺ and SO₄² varied greatly among the roots, stems and leaves, while those of K⁺, Mg²⁺ and Ca²⁺ were substantially the same. The contents of Cl^- and Na⁺ were similar, and they may be concomitant ions. S. physophora was a plant that accumulated SO₄ -Cl salt, and the background soil was Cl-SO₄ -dominated saline soil.(4)The roots of S. physophora took preference in selecting K⁺ and Mg²⁺ relative to soil; and the leaves took preference in transporting Cl^-, Na⁺ and SO₄^2- relative to the roots. The selection of ion absorption and transport was inconsistent and affected by the nutritional function of elements. Saline soil affects the nutrition physiology of plants. Investigating the nutritional status of naturally selected halophytes will provide useful reference data for saline agriculture. Ion absorption, distribution, and transportation within S. physophora which is grown in saline-alkali soil, are different from those within glycophytes. Mineral nutrition physiology is greatly influenced by the background soil. Secondary and micro-elements, i.e., Na, Cl, and S, become not only macro-elements but also hyperaccumulating beneficial elements in S. physophora. The levels of these elements in S. physophora are 2 to 60 000 times than those in crops. These ions are passively or actively enriched in S. physophora, compared with crops. The main damage caused by osmotic stress from soil salinity to crops is physiological drought resulted from cell dehydration. The way for plants to avoid dehydration is to accumulate organic osmotic regulators or inorganic ions. S. physophora mainly relies on absorbing and accumulating large amount of inorganic ions as osmotic regulators from the surroundings, which is the most economical way to osmotic regulation and lowering water potential, and thereby absorbing moisture from the high-salt soil solution. The roots then selectively absorb mineral nutrients based on the absorption of moisture. This is the important mechanism for euhalophytes to survive in saline soil.