| Coastal zone due to long-term exposure to wide,tide,sand flow function can form coastal dunes,on which there are the surface of the onshore windward and leeward slope.There were obvious differences between windward and leeward slope in the soil salinity,wind speed,atmospheric humidity environment?environmental heterogeneity?.However,Leymus mollis?Trin.?Hara can not only establish in the windward slope near high tide line and form single species,but also in the leeward slope coexist with some other plants.But it is unclear what physiological mechanism are involved in L.mollis on two slopes adapting to heterogeneous environment is,as well as if L.mollis grown on two slop had same in response to different wind speed in physiology.To answer those questions,in this study the antioxidant enzyme activities and osmoregulation contents in the leaves of L.mollis grown on the two slope under natural state and under artificial simulation with different wind blowing were investigated to understand the physiological mechanism of L.mollis wind resistance,and its the regulation mechanism of physiological plasticity,and to enrich plant wind theory,provide theory basis for coastal zone ecological restoration.The results were as follows:?1?In order to understand the biochemical and physiological mechanisms of L.mollis adapting to heterogeneous environment under nature,L.mollis grown on different location of 10 m,30 m,50 m?windward slope?and 70 m?leeward slope?far from the high tide on the coastal of Yantai were chosen to be a material used for this study.The contents of soluble sugar,proline,soluble protein,chlorophyll and the activities of antioxidant enzymes?SOD,POD and CAT?in the leaves of L.mollis grown in different location away from high tide line were measured during summer.The results showed that there was different environment between windward slope and leeward slope of coastal dune.On windward slope closed to high tide line?10 m?,there were higher in sea-wind speed,salt content,water content,where salt stress of soil was main growth limiting factor.On leeward slope of coastal dune?70 m?,there were higher in temperature,and lower in water content and salt content,where drought stress was main growth liming factor.But also there were markedly differences in kinds of antioxidant enzymes and osmosis-regulating substances between the leaves of L.mollis grown in windward slope and leeward slope.The leaves of L.mollis grown in windward slope?10 m?were maintained higher contents of chlorophyll,MDA and soluble sugar,higher activities of SOD and CAT.In contrast,the leaves of L.mollis grown in leeward slope?70 m?were maintained lower contents of chlorophyll,MDA and proline,lower activities of SOD,CAT and higher activities of POD.L.mollis grown in windward slope were maintained higher activities of SOD and CAT,higher soluble sugar contents that the purpose was adapted to the near high tide line's environment of high salinity by improve the osmotic potential to maintain moisture balance and inhibit membrane lipid peroxide to maintain the metabolic balance of active oxygen species.But L.mollis grown in the leeward slope?70 m?ware maintained higher activities of POD,higher proline contents that the purpose was adapted to the high temperatures and drought environment by improve the osmotic potential to maintain moisture balance.Under heterogeneous environment,the difference in kinds of antioxidant enzymes and osmosis-regulating substances of L.mollis that was the important behavior of physiological plasticity adapt to heterogeneous environment.?2?In order to understand whether there were differences between L.mollis grown in different slope direction in the response to different blowing of wind speeds in physilogy,an artificial wind blowing experiment with four wind speeds(0,5,9and 15 m·s-1)and seven levels of wind blowing time?10 minutes-1 hours?were conducted on the coastal dune of Yantai Sand in Autumn 2017.The contents of soluble sugar,proline,soluble protein,chlorophyll and the activities of antioxidant enzymes?SOD,POD and CAT?in the leaves of L.mollis grown in different slope direction under treatment of different wind speed were measured.The results shown that L.mollis of the two slopes have the same response to different wind speeds.With the increase of wind speed,the membrane permeability,MDA,proline content and POD activity of the two slopes were increased,while the water content of leaves,soluble sugar content,SOD and CAT activity tended to decrease.The study also found that physiological indexes were higher under weak wind blowing(5 m·s-1)than that of strong wind blowing(15 m·s-1).The study also found that in the natural state,L.mollis grown on the windward slope had significantly higher in the membrane permeability,the content of MDA and soluble sugar than that of leeward slope.While L.mollis grown on the windward slope had significantly lower in POD activity and proline content than the leeward slope.Although the different wind speed was failed to change the difference of L.mollis of two slopes in physiological index,it made physiological index difference between L.mollis of the two slopes increase or decrease.However,under different wind speed,the physiological regulation mechanism of L.mollis of different slopes showed the same,but the amplitude of physiological regulation is different,which fully demonstrated that L.mollis have strong physiological regulatory plasticity.In short,L.mollis grown in different slope-direction adapted to heterogeneous environment of coastal dunes and different wind speed by adjusting the antioxidant enzyme activity and content of the osmosis-regulating substances.It indicated that L.mollis had strong ability of physiological regulation to adapt different wind speed and showed its obvious physiological plasticity,which could be a key for L.mollis to be survival,growth and population expansion in heterogeneous environment and different wind blowing. |
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