Studies On The Shade And Drought Tolerance Of Three Species In The Genus Hemerocallis

Hemerocallis plants have good ornamental characters and strong resistance,and are suitable for urban green space even if drought or lack of illumination.So,they have great potential application.In this study,three species of genus Hemerocallis,including Hemerocallis lilio-asphodelus,H.fulva ‘Golden Doll' and H.minor,were used as the tested materials in a pot experiment.We set up 4 shading modes,including light,light shading(70% light),moderate shading(40% light)and severe shading(20% light),and another 4 kinds of drought stress,including no(normal water supply as control),mild,moderate,severe stress.Under the different shading and drought stress conditions,the 3species of Hemerocallis exhibited differences in morphological index,biomass,photosynthetic characteristics and physiological and biochemical indexes.The main conclusions are as follows:(1)The growth of 3 species of Hemerocallis were influenced by different shading treatments.Individual single flower number and leaf number per plant showed a decreasing trend and single leaf area showed an increase trend with the increase of shading intensity.In severe shade,ornamental characters of H.lilio-asphodelu and H.fulva‘Golden Doll' were adversely affected while H.minor was not significantly affected.(2)The chlorophyll content and chlorophyll b ratio were increased with the deepening of shading.The change trend of H.minor is more obvious,showing adaptation to low light environment.(3)Maximum saturation rate and light saturation point of H.lilio-asphodelu decreased with increasing and the maximum decrease was observed at 20% light.Maximum saturation rate and light saturation point at 40%~70% light.of H.fulva ‘Golden Doll' were higher,indicating H.fulva ‘Golden Doll' was adapt to a wide range of light.Maximum apparent quantum efficiency of H.minor was higher at 20%~40% light.Maximum saturation rate decreased slightly compared with full sunlight,showing strong shade tolerance.(4)The leave dry weight of the 3 species of Hemerocallis has no significant difference between the drought stress and CK.Root shoot ratio of H.lilio-asphodelus and H.fulva‘Golden Doll' decreased under drought stress which indicates that these two kinds of plants are sensitive to drought stress,lack of water has great influence on the growth of aboveground part.The root shoot ratio of H.minor was equal under different drought stress,and it should have a more powerful mechanism of drought resistance.(5)The contents of Pro,POD,CAT and MDA increased with drought stress.The excised leaf water loss rate decreases between H.fulva ‘Golden Doll',H.lilio-asphodelus and H.minor.Critical soil moisture content decreases between H.minor,H.lilio-asphodelus and H.fulva‘Golden Doll'.Comprehensive comparison of index in morphology,enzyme system,leaf water loss rate and changes of body under different drought stress,the drought tolerance of 3 Hemerocallis in the order from strong to weak is:H.mino,H.fulva‘Golden Doll' and H.lilio-asphodelus.