Study On Physiological And Ecological Characteristics Of Platycarya Longipes In Karst Ecological Fragile Area Of Guizhou

In this paper,Platycarya longipes was used as the research object.Through the determination of physiological and biochemical indexes related to Platycarya longipes in different spaces and months,and the method of controlling water and controlling calcium by potted plants,the study of different flavors and seasons of Platycarya longipes physiological response and growth and physiological and biochemical responses that occur under different soil moisture and Ca²⁺treatments.Through the study of the response mechanism of Platycarya longipes under different conditions,it provides some help for exploring the maintenance mechanism of Platycarya longipes,provides a theoretical reference for vegetation restoration in karst areas,and provides a certain theoretical basis for environmental management and ecological restoration in karst areas.The results show that:?1?On the space,the trends of physiological indicators are generally sunny?east and north?>cloudy?south and west?and upper>middle>lower.Analysis of variance showed that there was no significant difference between the results of the indicators in both the horizontal and vertical directions,so the spatial variation had little effect on the growth and development of Platycarya longipes.However,it can be found from the change of enzyme activity that there is always one enzyme activity in different spaces in both vertical and horizontal directions,and the spatial enzyme types are different,indicating that Platycarya longipes of different leaves may have different reactive oxygen free Base cleaning mechanism.?2?In the month,except for chlorophyll,malondialdehyde,soluble sugar and CAT,there were significant differences in other indicators.Further studies on different seasons showed that except for chlorophyll,malondialdehyde,CAT and POD,the other indicators were also There are significant differences.The small difference between chlorophyll and malondialdehyde indicates that the change of time has little effect on the growth of Platycarya longipes;while the difference of osmotic adjustment substances?soluble sugar and valine?is obvious,indicating that with the change of month and season,Platycarya longipes can actively accumulate soluble sugar and proline in the cell,maintaining the metabolic balance inside and outside the cell membrane.In terms of the change of protective enzyme activity,except for the month or the season,except for the SOD activity,the other three enzymes basically increased first and then decreased with the change of the month,indicating different The scent of Platycarya longipes has different active oxygen scavenging mechanisms.?3?Under water stress,with the increase of stress degree and the prolongation of stress time,the seedlings of Platycarya longipes could grow,but the color of leaves of Platycarya longipes seedlings became lighter,yellower and even withered,and the growth rate decreased significantly.The phenomenon of seedling height and ground diameter growth is continuously deepened.The physiological characteristics showed an increasing trend with time,but the difference was not significant.However,with the change of stress degree,the soluble sugar content,SOD activity and malondialdehyde concentration of Platycarya longipes increased first and then decreased,and the POD activity showed The trend of APX activity decreased first and then increased,while the activity of CAT showed a trend of up-down-up,and the indicators were significantly different,indicating that Platycarya longipes had strong adaptability to water stress.?4?Under different Ca²⁺treatments,the growth of Platycarya longipes was different.Under the low calcium treatment,the height of Platycarya longipes seedlings was 1.027 times,1.07 times,1.102 times and 1.158 times of ck.It is indicated that the low calcium concentration has a certain promoting effect on the growth of Platycarya longipes.The seedling height of Platycarya longipes under medium calcium and high calcium treatment was 0.985 times,0.987 times,0.967 times,0.956 times and 0.983times,0.979 times,0.951 times and 0.922 times,respectively.It indicated that the medium and high calcium stress had a certain inhibitory effect on the morphogenesis of the seedlings of Platycarya longipes.Similarly,calcium treatment significantly promoted the thickening of the diameter of the seedlings of Platycarya longipes scented seedlings,while the medium calcium and high calcium treatment significantly inhibited the growth of the diameter of Platycarya longipes scented seedlings.The differences in seedling heights in different periods were extremely significant,and the differences in ground diameters were not significant,but they all showed an upward trend,indicating that regardless of the degree of stress,with the extension of treatment time,the seedlings of Platycarya longipes can maintain a certain growth trend,only The change of seedling height was greatly affected by time,while the ground diameter was not affected much.Further,it showed that the seedlings of Platycarya longipes had strong anti-calcium ability.Physiological characteristics,SOD activity,CAT activity and MDA content increased first and then decreased under different Ca²⁺treatments.POD activity and APX activity showed a first decline and then an upward trend,but the increase of MDA content was small,and the increase of CAT activity was larger.Under different calcium treatment time,except for the decrease of CAT activity under high calcium stress,the other indicators showed an increasing trend,and the difference of other indicators was not significant except for the difference of malondialdehyde.The cell membrane of the leaves of Platycarya longipes was damaged,but in a certain calcium concentration and treatment time,the seedlings of Platycarya longipes could clear the stress by the obvious changes of the activities of four protective enzymes?SOD,POD,CAT and APX?.Excess free radicals reduce the damage suffered by Platycarya longipes scented seedlings.SOD and CAT were dominant under low calcium stress,SOD,CAT and POD were dominant under medium calcium stress,and POD was dominant under high calcium stress.APX was less than control because of its activity change,indicating that APX is under calcium stress.The main regulation effect can not be obtained;further,combined with the change of malondialdehyde concentration,it can be seen that although the seedlings of Platycarya longipes are more adaptable to different calcium stress,the adaptability will gradually weaken with the extension of the stress time.?5?In terms of photosynthetic characteristics,the parameters such as the content of the scented photosynthetic pigments are significantly affected by the canopy,and these parameters are less affected in the direction.Except for AQE,the photosynthetic parameters showed a positive correlation with the increase of the vertical space of Platycarya longipes,while the photosynthetic pigment content showed a negative correlation change.In the direction,the photosynthetic physiological parameters had no significant correlation,but the average of the north direction parameters.The value can represent the photosynthetic characteristics of the entire canopy.