Study On The Water Stress Tolerance Of Several Hosta

Hosta is the excellent ground cover plants in shade environment,they are famouse for green jade,elegance and native.There was no report on water stress tolerance of Hosta.In this article Hosta plantaginea,Hosta ensata,Hosta.'Gold Standard',Hosta.'Golden Tiara' and Hosta. 'Middle Ridge' were investigated.Based on the experiment with three comparative methods,the PEG penetration stressing,the natrual drought stressing and the waterloggring stressing.Observed and measured the plant morphology and the dynamic changes of physiological indexes under different water stress.Used the wilting index and subordination function method synthetical studied the toleranct of different water stress for different species(varieties) of Hosta.Comparison the drought resisitance and waterlogging resistance of different species(varieties) of Hosta,provide a theoretical basis for Material selection for garden plants.The research structure indicated that:(1) Deal with PEG6000 to two seedings of Hosta,wilting insex increased and RWC desended with the increase of intimidate degree and hours,RWD and membrance permeability increased.With 10%and 20%PEG treatment,the effects are smaller on seedings,with 30% PEG treatment,the seeding could be recovered normally in the recovery solution within 7 days and 10 days.(2) Wiling index eveluation results under drought stress:The wilting insex increased with the increase of intimidate degree and hours.Effects of Hosta plantaginea tolerable 36 days of natural drought stress;Hosta.'Golden Tiara' for 30days;Hosta.'Gold Standard' for 33 days; Hosta ensata for 29 days;Hosta.'Middle Ridge' 28days.The drought tolerance from strong to weak order:Hosta plantaginea＞Hosta.'Gold Standard'＞Hosta.'Golden Tiara'＞Hosta ensata＞Hosta.'Middle Ridge'.Under drought stress,the relative water conten and chlorophyll decended with incress of the stress level,membrance permeability and water saturation deficit,prolin gradually increased,the trend of MDA and soluble protein content is more complicated.Differences between different meterials significant.Evaluation results of the drought resisitance for five Hosta by membership function:Hosta plantaginea belongs to strong type of drought resisitance(X=0.85),Hosta.'Gold Standard' belongs to medium types of drought resistance(X=0.76),Hosta.'Golden Tiara' and Hosta ensata belongs to weak type of drought resisitance(X=0.42,X=0.37),H.'Middle Ridge' belongs to no resisitance cultivar(X=0.12).(3) Flooding stress 63d does not caused the harm of death on five Hosta.,but the impact on growth is seriously.Leaves of Hosta plantaginea and Hosta ensata truned yellow and the roots rot after 30d's stress.Growth of H.'Middle Ridge' and Hosta.'Gold Standard' is still long after 30d's stress,and had a large number of new roots to adapt to flooding environment.Under flooding stress,the change trends of physiological indicaors are complex,Differences between different meterials significant.Leaf relative water content,soluble protein content lower,the membrane permeability of leaves,the membrane permeability of roots,proline and MDA were increased.Use the membership function method evaluate waterlogging resisitance among 5 Hosta species.The result is:H.'Middle Ridge'＞H.'Gold Standard'＞H.'Golden Tiara'＞Hosta plantaginea＞Hosta plantaginea.