Effects On Physiological Characteristics Of Hemerocallis Middendorfii Species And The Role Of Calcium Mitigation Under Water Stress

An experiment was conducted to study the morphological and physiological changes in Hemerocallis middendorfii cv.butter curls and H.middendorfii cv.little bumble bee under osmotic stress and soil drought stress,and analyzed effects of Ca²⁺ on physiological characters and cell ultrastructure of H.middendorfii cv.butter curls leaves under osmotic stress.Result shows:(1)Under osmotic stress,the relative water content of leaves,the content of chlorophyll decreased gradually,the relative membrane permeability,the contents of MDA,the content of dissociative proline and soluble sugar content increased,while Contents of soluble Protein, Activity of SOD,POD and CAT increase first,then decrease,adjust to the contents of Osmotic stress substances,the activity of SOD,POD and CAT to increase the relative water content of leaves,reducing the relative membrane permeability and the contents of MDA,and removal reactive oxygen,so as to the ability of drought-stress.A comprehensive analysis of the results is determined that H.middendorfii cv.butter curls and H.middendorfii cv.little bumble bee have better drought resistance,and then the latter is better than the former.(2)Under soil drought stress and rewatering,the relative water content of leaves decreased rapidly,the degree of H.middendorfii cv.butter curls leaf wilting is small in early days,in the late its leaves was injured more seriously than H.middendorfii cv.little bumble bee.After rewatering H.middendorfii can recover normal.The change of physiological indicators is similar to the regular of osmotic stress.But H.middendorfii cv.little bumble bee indicators of the physiological changes in the pre-magnitude larger than the rate in the latter half of H. middendorfii cv.butter curls.After rehydration,H.middendorfii cv.little bumble bee and H. middendorfii cv.butter curls physiological indicators can be restored to the basic difference with the control level was not significant.(3)Under osmotic stress,Ca²⁺ could effectively inhibit the relative water content,decrease photosynthesis rate and improve or protect the activity of SOD,POD and CAT.Ultrastructure observation showed that Ca²⁺ could stay the cell structure of organdie such as chloroplast and mitochondria etc.