不同展叶物候期胡杨离子分布、吸收和运输特征及其与土壤盐分关系

为明确胡杨(Populus euphratica )的离子分布、吸收和运输规律,探讨胡杨适应盐渍环境的生理机制,以不同展叶物候期（萌芽期、展叶期、叶片快速发育期、叶片成熟期）的胡杨为研究对象,测定其根、主干、老枝、幼枝和叶片中的可溶性盐离子含量,并对各离子吸收、运输和分配特征进行研究,同时结合林下土壤盐分特征,探讨胡杨离子分布与土壤盐分的关系,结果表明:随着展叶物候的变化,胡杨通过对离子吸收、运输和分布规律的差异满足生长发育的需要及对环境的适应。（1）根系选择性吸收K+、Ca2+和Mg2+的能力随展叶物候变化而呈先升后降趋势,多以叶片快速发育期为最高,恰与土壤中总盐及Na+、Cl-含量变化趋势相反。（2）离子从根系-主干及幼枝-叶片的运输能力随展叶物候的变化表现为先降后升的相反趋势,且多以叶片快速发育期为最低。（3）各器官中Na+和K+含量在展叶过程中变化不大,而在叶片成熟期有显著升高,且此期Na+以根中含量最高,K+以叶片中含量最高;叶片和根系中Ca2+、Mg2+含量随展叶物候变化整体呈升高趋势。（4）展叶物候期胡杨器官离子与土壤离子相关性表现为:萌芽期,各器官离子含量受土壤盐分影响较小,指标间相关性多不显著;展叶期,根中Na+与土壤离子成正相关,幼枝和主干K+与土壤多呈负相关;叶片快速发育期,幼枝Mg2+、根中Na+均与土壤离子呈正相关;叶片成熟期,各器官离子含量受土壤离子影响较小。

Distribution, Uptake and Transport Characteristics of Populus euphratica Ions at Different Leaf Phenological Stages and Their relationship with Soil Salinity

In order to clarify the ion distribution, absorption and transport laws of P. euphratica, and to explore the physiological mechanism of P. euphratica"s adaptation to the saline environment, P. euphratica was used as the research object to determine the soluble salt ion content in the roots, trunks, old branches, young shoots and leaves, and study the uptake, transport and distribution characteristics of each ion, combined with the salt characteristics of understory soil. The relationship between P. euphratica ion distribution and soil salinity was discussed, and the results showed that:With the changes of leaf-unfolding phenology, P. euphratica meets the needs of growth and development as well as the adaptation to the environment through the difference of ion absorption, transportation and distribution rules. (1) The ability of selective absorption of K+, Ca2+ and Mg2+ by roots increased firstly and then decreased with the changes of leaf-unfolding phenology, and most of them were in the rapid leaf development stage as the highest, which was just the opposite to the change trends of total salt and Na+ and Cl- contents in soil. (2) With the changes of leaf-unfolding phenology, the transportation capacity of ions from root to trunk and juvenile branch to leaf presented the opposite trend of first decline and then rise, and most of them were in the rapid development period of leaf as the lowest. (3) Na+ and K+ contents in different organs changed little during the leaf developing process but increased significantly during the leaf mature period, in which the content of Na+ in root was the highest and that of K+ in leaf was the highest. The contents of Ca2+ and Mg2+ in leaves and roots generally increased with the changes of leaf-unfolding phenology. (4) The correlation between organ ions and soil ions of P. euphratica in the leaf-unfolding phenophase is as follows: In the germination stage, the ion content of each organ is less affected by soil salt, and the correlation between indicators is mostly insignificant; During the leaf-unfolding stage, Na+ in roots positively correlated with soil ions, while K+ in young branches and main stems negatively correlated with soil ions. During the rapid development of leaves, Mg2+ in young branches and Na+ in roots were positively correlated with soil ions. The ion content of each organ was less affected by soil ions during the leaf mature period.