Study On The Structure Of The Leafs Of Three Plants Of The Genus Atriplex And Their Tolerance To Environmental Stresses

The genus Atriplex, tyical plants in arid regions and semi arid regions, are adaptable with strong resistance to drought, salt and alkaline. Desert plants for revegetation in degenerate pastures and a good feed for domescated animals, they are important shrushes in arid areas in the west of USA. In the late of 1990, they were indroduced into Qinghai province, XinjiangUygur Ethnic Autonomous Region, and Ningxia Hui Ethnic Autonomous Region as their original habitat is similar to the west arid areas in China. The cultivation experiment there shows the genus Atriplex should have great potential for development there. This thesis chooses Atriplex Canescens, Atriplex Gardneri and Atriplex Tridentate as subjects which grow in the nurseries of Forestry College, Northwest Uni.of Agriculture and Forestry. Their leafs are used as experimental material, which are made into paraffin sections and whose leafs'anatomical structures are observed. The thesis, by analyzing the connection between the leafs'structure and their resistance to drought, salt and alkaline, tries to expose the cause of the genus Atriplex'drought resistance and tempts to provide theoretical foundation that the genus Atriplex are ideal plants to be grown in the arid areas of the west China. Through study a main conclusion is drawn as followed:1.atomically, the leafs of the three plants of the genus Atriplex contain salt bladders covering epidermis, which have different layers when the upper and lower epidermis are different. These epidermises are multible epidermis consisting of epidermis and lower epidermis. Mesophyll, made of palisade tissue, is closely collocated; whose secretory cells and aqueous cells contain crystals. Vascular bundles are well functional and closely collocated with vascular bundle sheath. The above features show that these three plants have strong resistance to drought, salt and alkaline.2.An analysis of variance for drought indexes such as crystal in leaf blades and midribs, tectum on upper and lower epidermises, thickness of leaf blade and thickness of upper and lower epidermises in three plants'leafs shows that these three plants are considerably different with different resistance to drought, salt and alkaline.3.s we know, both surfaces of the three plants'leafs are covered with salt bladders, whose function is to reduce transpiration. The tectum of lower epidermis of Atriplex Tridentate averages 2.3 layers, that of Atriplex Gardneri averages 1.71 layers and that of Atriplex Canescens 1.43 layers. The tectum of upper epidermis of Atriplex Tridentate averages 2.8000 layers, that of Atriplex Gardneri averages 2.0196 layers and that of Atriplex Canescens 1.7843 layers. These figures show Atriplex Tridentate is more drought resistant than Atriplex Gardneri and Atriplex Canescens. The thickness of lower epidermis of Atriplex Tridentate is 8.25, that of Atriplex Gardneri is 10.59 and that of Atriplex Canescens 12.60, which proves that Atriplex Tridentate is most salt and alkaline resistant.