Effects Of Salt Stress On The Growth And Physiological Properties Of Three Hitom Stocks Varieties

This thesis, based on the first year stump seedlings of the three different cherry-apple tree species, with potted salt stress method, observed the responding mechanism to salt stress of Malus baccata,Malus hupehensis,Malus doumeri from the change of the features, physiology, biochemistry reaction etc. Main research findings are as follows:Investigation on potted plants under salt stress shows that salt tolerance of the three different cherry-apple tree species is different, there are three grades of salt tolerance, the order is as below: Malus hupehensis>Malus doumeri>Malus baccata)Salt stress restrains the growth of the relative diameter and relative height of the three different cherry-apple tree species. It also restrains the photosynthesis of each tree. With the increase of salt stress degree, net photosynthetic rate(Pn), stomatal conductance(Cond) and transpiration rate(Tr) of each tree decreases, while intercellular CO2 concentration(Ci) increases. Fv/Fm,ΦPSⅡare lower than control, the chlorophyll content decreases. Salt stress increases the cell membrane permeability. With the increase of salt stress degree, RWD becomes more obvious than the control and osmoregulation substance of praline increases.With the increase of salt stress degree and processing time, MDA content increases, while sod activity, soluble protein and soluble sugar all increases first and then decreases and are lower than the control under heavy salt stress.With the increasing of salt concentration,the changes of physiological indexes of Malus baccata is more obvious than Malus hupehensis and Malus doumeri. Malus hupehensis had much more Na+ contention in root than other trees under control treatment. It could restrain the absorbtion of Na+ in root to adapt to the salt stress.