Response Of Epicuticular Waxes To Different Water Treatments In Leaves Of Hosta ‘Halcyon’

The Hosta ’Halcyon’ is a typical representative of the blue leaf variety,and the leaves are covered with wax.Leaf color is an important factor affecting the ornamental value of Hosta,which is closely related to the shape and quantity of epicuticular wax,while epicuticular waxes are susceptible to soil water conditions.In this study,the leaves of Hosta ’Halcyon’ wiped wax under drought stress(relative water content 50%)and different water treatments(T1: relative water content is 90%-85%;T2: relative water content is 75%-70%;T3: relative water content is 55%-50%;T4: relative water content is 35%-30%),were carried out to determine the photosynthesis characteristics,fluorescence characteristics and other physiological characteristics of leaves,and to explore the effects of water and wax content on the growth and development of Hosta ’Halcyon’,and to analyze the relationship between different water treatments and plant growth,epicuticular wax synthesis and ornamental value,and provide the necessary theory for the cultivation and conservation of this type of Hosta variety in northern areas.The main findings are as follows:(1)After artificial removal of wax,the net photosynthetic rate,transpiration rate,stomatal conductance,water use efficiency,Fv/Fm value and chlorophyll content of the Hosta ’Halcyon’ leaves of with wax intact were higher than those of wiped leaves,and the permeability and water loss rate of leaves with wax intact was lower than that of wiped leaves.(2)Under four different water treatments,with the decrease of soil water content,the content of plant epicuticular wax increased,and the leaves of Hosta ’Halcyon’ decreased the stomatal opening and transpiration rate,decreased loss of water and improved its water use efficiency by increasing the content of epicuticular wax,thereby its own drought resistance was enhanced,and playing an effective self-protection under adverse environmental conditions;with the further increased of stress,leaf epicuticular wax synthesis was blocked,the content of epicuticular wax decreased gradually,which led to a significant decrease in photosynthetic rate and water use efficiency(P<0.05).(3)Water stress caused the synthesis of chlorophyll to be blocked and the chlorophyll content of Hosta ’Halcyon’ decreased significantly,which led to the photosynthetic capacity of Hosta ’Halcyon’ declined and affected the growth and ornamental value of Hosta ’Halcyon’.(4)The growth potential and ornamental value of Hosta ’Halcyon’ under T2 were the best.In summary,epicuticular wax of Hosta ’Halcyon’ plays an important role in reducing leaf surface permeability,reducing water loss,and improving water use efficiency,and the relative water content of 75%-70% is most beneficial to the growth of Hosta ’Halcyon’,which has the highest ornamental value.