Comparative study about the anatomical structure for stem of Carum carvi in different elevations of alpine-cold area
We compared and analyzed the primary anatomical structures for stem of Carum carvi on five different alti-tudes by paraffin section methods,and observed the structure with unidimensional and two-dimensional (area)index properties,in order to find out the change rule of structures for stem of C .carvi with the rising of elevation,which could provide basic information for the development and utilization of C .carvi .The test showed that stem primary structure consisted of cortex and vascular cylinder.With the altitude increasing,the thickness of epidermis and pith, the width of pith ray and the area of aerenchyma gradually increased,but the ratio of vascular tissue to fundamental tissue gradually reduced;the number of layers and thickness of cortex,the number and thickness of vascular bundle gradually decreased,however,the development degree of vascular bundle and the diameter of duct gradually increased. The thickening of epidermis could reduce the losing their body heat and decrease the damage from strong ultraviolet rays;The increasing of ratio of fundamental tissue was conducive to store more physiological regulatory substances, increase of cold resistance abilities in the plant;The development of aerenchyma could reduce the diffusional resist-ance of the alr inside the plant,channel being formed along aerial parts to underground part,and also could increase the plant's buoyancy,reduce the proportion of plants.The varying of anatomical structures for stem of C .cavri during different elevation reflected plant adaptations for environment.But in this experiment,some special phenomenon was observed,the number of layers and thickness of cortex in C .carvi stem,this phenomenon was reported in the aerial stem structures of Kobresia pygmaea and its mechanical tissue of aerial part had a decline meanwhile underground part had a rise.Whether this kind of phenomenon exists or not,we must further carry on study about anatomical structures for root of C .carvi .In this study,we also found that the number and thickness of vascular bundle gradual-ly decreased,however the development degree of vascular bundle and the diameter of duct gradually increased with the increasing of the altitude.The possible reason was that its low temperature and short frostless period were under the high altitude conditions,the plant developed more completely under the high altitude areas than the low altitude areas in same growth period.It also reflected plant adaptations for environment.And the problem about development degree of the same plant in different altitudes still need further research.
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