Physiological Response Of Hydrangea Macrophylla To Drought Stress And The Effect Of Drought On Leaf Structure

Hydrangea macrophylla L.has green leaves,large flowers,rich and colorful flowers and long viewing period.It has high ornamental value and has increasingly become the main potted ornamental flowers and trees in China.However,it is rarely used in landscaping in northern China,and poor drought resistance is one of the main reasons.In this experiment,four different varieties of Hydrangea were used as test materials to study the drought damage performance of different varieties under soil drought stress,observe the effect of drought on the leaf structure of Hydrangea,clarify the physiological response of different Hydrangea varieties to drought stress,and compare the drought tolerance of different varieties.The main results are as follows:1.Physiological effects of drought stress on different varieties of HydrangeaUnder drought stress,the physiological indexes of four varieties of Hydrangea varied.The relative water content of leaves showed a downward trend with the deepening of drought,among which the relative water content of ’Camilla powder’ leaves decreased less,and the relative water content of ’endless summer’ leaves decreased more’ The soluble sugar content of ’blue butterfly’ was higher than that of the other three varieties;During drought stress,the content of superoxide dismutase and peroxidase in all varieties increased first and then decreased.The content of superoxide dismutase and peroxidase in ’Camilla powder’ variety was higher and that in ’blue butterfly’ variety was lower;The malondialdehyde content of all varieties generally showed an upward trend with the extension of drought time.Among them,the increase of malondialdehyde content of "endless summer" variety was the most obvious,and the increase of malondialdehyde in "Camilla powder","blue lover" and "blue butterfly" varieties was lower than that of "endless summer".According to the drought damage index,the order of early tolerance of four varieties of Hydrangea is’ endless summer’>’ blue butterfly’>’ Camilla powder ’>’ Blue lover ’.2.Response Characteristics of Leaf Structure and Drought Tolerance of Different Varieties of HydrangeaThere is a great relationship between the leaf anatomical structure(upper epidermis thickness and lower epidermis thickness)and drought tolerance.The results show that;Except for ’Camilla powder’,the thickness of upper epidermis is greater than that of lower epidermis,and the stomata of Hydrangea are only distributed in the lower epidermis of leaves.The difference of anatomical structure among varieties reached a significant or extremely significant level,and four main indexes affecting plant drought tolerance were screened,which were leaf thickness,leaf epidermis thickness,stomatal size and midvein thickness.