不同发育时期中宁圆枣果实结构特征的研究OA

Taking the fruits of Ziziphus jujuba Mill cv.Zhongningyuanzao at different developmental stages as experimental materials,the paraffin section method was adopted to explore and study the developmental characteristics and structural change patterns of the fruits at different developmental stages,providing an important theoretical basis for the rational development and research of Ziziphus jujuba Mill cv.Zhongningyuanzao plant resources.The results showed that:① In the early stage of expansion,cell growth was slow.The exocarp was composed of 5 to 6 layers of neatly and closely arranged flat cells,while the mesocarp was mainly composed of closely arranged thin-walled cells.The intercellular spaces were not obvious,and there were many secretory cavities formed by secretory cells.The vascular bundles of the fruit belong to the outer flexible infinite vascular bundles,with a large number,especially the vascular bundles of the endoderm had a large number and concentrated distribution.At this time,a single vascular bundle was developing,and there were also two vascular bundles developing back-to-back.Their xylem was mainly composed of annular vessels.② During the rapid expansion period,cell development was rapid,the stratum corneum appeared in the exocarp,the number of epidermal cell layers decreased,and a subepidermal transition occurred between the exocarp and mesocarp.At this time,the parenchyma cells in the mesocarp developed rapidly,gradually increasing in volume from the outside to the inside,and were loosely arranged.Some even formed a reticular structure,enclosing larger cavities.Within the same field of view,the number of vascular bundles decreased,and most of the vascular bundles developed in pairs,back-to-back,or in groups of three or four.③ During the coloring stage,the epidermal cells had already differentiated into round and oval shapes,and their arrangement was not as tight as in the previous two periods.It was more difficult to distinguish the epidermal cells from the internal cells.The cellular cavities in the mesocarp further enlarged and increased in number,which was equivalent to having fewer vascular bundles in the field of vision.④Compared with the coloring stage,the internal structure of the fruit in the mature stage remained basically unchanged,the cavity space formed by parenchyma cells continued to increase,and there was no significant change in the size and number of vascular bundles.The pigment in the epidermal cells of the exocarp increased rapidly,causing the epidermis to change color.It can be seen that the tissue structure and cell morphology of the exocarp,mesocarp and endocarp have different changes and characteristics at different times.