Effect Of Water Stress On Drought-resistant Physiology Indexes And Anatomical Structure In Armeniaca Sibirica

In this research we took the pot-cultured 3-year-old Armeniaca Sibirica as the test materials.In order to ascertain the drought-resistant mechanism of Armeniaca Sibirica,the experiment was studied the physiological index of Armeniaca Sibirica and microstructure of the new roots and leaves on different soil water steress, using the method of controlling the field soil relative water content. The results showed that:under different degree of water stress, along with the time of water stress, the RWC decreased;the chlorophyll content decreased; Proline content continued to increase,whereas the soluble protein content continued to decrease.The soluble sugar content showed increasing first and then decreasing. The sorbitol content continued to increase. The PMP conductivity and MDA content of Armeniaca Sibirica leaves of every treatment continued to increase.With protective enzyme activity ,the change of SOD,CAT,APX activity was consistent,which continued to increase first and then decreased; the change of POD activity was delayed,which showed decreasing a little in the first week and then increasing,the same as other protective enzyme which showed increasing first and then decreasing.The seasonal change of the soluble sugar content and the sorbitol content of the Armeniaca Sibirica branches showed increasing first later decreasing then increasing again ,whereas the seasonal change of the starch content showed increasing first and then decreasing.The root tips of new roots in 5cm areas,the endodermis cell wall thickened earlier than the generation of casparian strips,that is to say, the cell wall thickened first then casparian strips appeared. Under the drought condition, the endodermis cell wall thickening significantly earlier than the control material , That is, under the drought condition, in order to prevent the excessive loss of water,the endodermis cell wall appered the phenomenon of thickening earlier.With further stress treatment,the palisade tissue of mesophyll had became thicker,and the cells became much more longer, while the thickness of spongy tissue became relatively smaller as the result of the structure became more closer.The cells of perpendicular to cross section of the leaf vein became more smaller,also the intercellular space become more smaller. This change of the cells strcture may play an important role in preventing the excessive loss of water of Armeniaca Sibirica leaves.Compared with the control, under the drought condition, the large number of starch grains in the cells of Armeniaca Sibirica mesophyll tissue decreased even disappeared.It was because that the high temperature stress damaged the chloroplast structure, so that the starch was broken down,.and transferde to every nutrition genital by the form of sugar,then participated the metabolism.