Study On Evaluation Of Hemerocallis And Sedum And Propagation And Drought Resistance Of Sedum Cultivar

New cultivars of Hemerocallis and Sedum, introduced from Holland to Beijing area, including Hemerocallis 'Chicago fire' ( H4 ) , Hemerocallis 'Mini Stella' ( H5 ) , Sedum alboroseum 'Mediovariegatum' (S2) , Sedum 'Purple Emperor' (S3) , Sedum 'Frosty Morn' (S4) and Sedum 'Autumn Joy' (S5) were studied for phenological calendar, and evaluation of ornamental value. Cultivars of Sedum which show the highest ornamental value were further employed for studying the drought resistance and water use efficiency. Below are the main results.After one year of observation, H4 and S5 showed excellent characteristics. The two cultivars sprouted in late March. The florescence of H4 lasted from late June to early July and S5 from early September to early October. The ornamental characteristics of S5 after blooming could last to late November. On the basis of introduced cultivars, the research discussed standards of appraisal system about Hemerocallis and Sedum, evaluation indexes about Hemerocallis include the number of flowers, flower color, flower diameter, blooming time of flower, plant types and root division ability .etc, evaluation indexes about Sedum include plant types, leaf color, flower color, ornamental characteristics after blooming and root division ability .etc. Based on the evaluation system, H2, H4, S1 and S5 were on the top of the list, similar to the observation in the fields.The study on S5 cuttage in different period of growing season indicated that, the cuttage of S5 could be done in any period of growing season, and the rooting rate could reach 100 percent, and there were 3-4 rooting points. In summer with high temperature, the rooting rate reduced to 40 percent and in September and October was also 80-90 percent. The cuttage could be conducted in simple greenhouse without any pretreatment.The rooted cuttings of S5 were cultivated in nutrient solution and PEG solution with different concentration of 10 %, 20 % and 40 %, which to study the drought resistance of S5. Compared with control, drought stress influenced appearance of S5, and growth was limited, fresh weight retention rate was decreased. Leaf water potential, Fv/Fm, Fv/Fo and ΦPS II also decreased with different degrees. The content of leaf soluble protein and qN increased while the content of MDA showed the same trend with control. The drought stress caused by PEG solution influenced growth and physiological and biochemical indexes of the treatment compare with the control, However there was not distinct difference among three degrees of treatment throughout multiple comparisons. The rooted cuttings of S5 performed strong ability to resistant to drought stress. Plants with different treatments were rewatered after 6 and 11 days drought stress, and all the plants could grow regularly in ground substance.The growth, physiological and biochemical changes of pot-cultivated S5 mature plants were studied under drought stress. Along with decrease of soil water, the growth of treated plants were limited, blooming time was advanced, and leaf water, leaf water potential, Fo, Fv/Fm, Fv/Fo and ΦPS II also decreased, while qN, the content of protein and MDA increased along with the progress of stress, the day-time photosynthesis was failed to be monitored after 22 days drought stress. The change of content of malic acid in leaf of treated plant, indicated that S5 could switch to CAM pathway under 22 days drought stress, that S5 showed the characteristics of the facultative CAM plant. The drought stressed plants did not die after 56 days showing a high drought resistance. Drought stress also influenced sprouting time and growth of the treated plants in the next year.Changes of water use efficiency of S5 mature plants under drought stress was studied meanwhile. The results showed that, instantaneous water use efficiency increased relatively after 12 days water stress compared with control, and the carbon isotope composition (δ¹³C) increased 3.24‰ compare to that in the control plant after 50 days of drought stress. All of these indicated that Sedum S5 apparently is an extremely drought-resitant cultivar.