塔克拉玛干沙漠腹地人工绿地三种灌木的离子吸收特性

塔克拉玛干沙漠腹地人工绿地长期使用矿化度 4.0g/L以上的地下水灌溉 ,柽柳、梭梭和沙拐枣三种灌木仍然能够正常生长 ,表现出较强的抗盐特性。通过对三种不同年龄的灌木及其根、茎和凋落物的盐分分析 ,表明 :不同种类和年龄灌木对可溶性离子的吸收特性存在较大的差异 ;同一种灌木不同器官的离子吸收特性差异显著 ,表现出三种灌木在抗盐机理方面不同的生理和生态学特性 ,即 :柽柳从土壤中吸收的大量盐分离子 ,通过叶片的泌盐腺排出体外 ,使植物体内的盐分离子含量保持在相对较低的水平 ,这类植物属于泌盐类植物 ;梭梭能够从外界环境吸收大量的盐分 ,在植物体内储藏 ,并且依靠植物肉质同化枝吸收大量的水分 ,使得植物体内的盐分浓度维持在一定的限度内 ,这类植物属于盐多汁类植物 ;而沙拐枣通过根部运输系统的超滤 ,使得过量的盐被阻止在体外 ,保持植物体内较低的盐分浓度 ,此类植物主动避开盐分 ,属于拒盐类植物

Absorption Characteristics of Ions in Three Species of Shrubs of the Artificially-planted Greenbelts in the Hinterland of Taklamakan Desert

The artificially-planted greenbelts in the hinterland of Taklamakan Desert have been irrigated by saline water with a salt content over 4g/L for many years, the Tamarix ramosissima, Holoxylon ammodendron and Calligonum caput-medusae can still grow normally, which proves that these three species of shrubs have a strong salt resistance. According to our analyzed results of plant samples, there is a distinct difference in absorbtion characteristics of ions from these three species of shrubs, also from the different parts, such as in roots, branches and emarcid things, as well as from the different growing ages of the shrubs, that is to say they have the different mechanism to withstand salt. All these are dependent on the physiological and ecological properties of the three species of shrubs. Tamarix ramosissima is a species of plants to dischange out a lot of salt ions by salt glands of leaves so as to maintain a low content of salt ions; Haloxylon ammodendron has the great salt endurance and succulent assimilation branches so that it draws and stores a big quantity of salt ions and water in the plants to keep a low content of salt ions, so Haloxylon ammodendron can still grow normally under irrigation with saline water for many years; Calligomum caput-medusae belongs to a species of plants to avoid salt actively by filtration of the roots and branches to maintain a low content of salt ions in the plants.