Effects Of Simulated Warming And Precipitation Change On The Physiological And Ecological Characteristics Of Uncaria Macrophylla

Climate warming caused by greenhouse gas emissions and the frequent occurrence of extreme precipitation events have become the main climatic factors restricting plant growth and development.Temperature and water are indispensable environmental factors for plant growth,and changes in both will have a series of effects on physiological processes such as growth and development of medicinal plants,photosynthesis,material metabolism,and accumulation of medicinal ingredients.Uncaria rhynchophylla.is an important medicinal plant resource in China and has significant clinical efficacy in the treatment of depression,hypertension and other diseases.In this study,U.was used as the experimental material to study the two temperature levels of control temperature?average temperature?and elevated temperature?increased temperature 5??by using artificial climate incubator.Three water gradients of 45%?W-45%?and 75%?W-75%?reduction in precipitation and their synergistic effects on the physiological and ecological characteristics of U.,revealing the response mechanism of U.to temperature,precipitation and their synergistic effects It is of great significance to accurately assess the response and adaptation of medicinal plants to climate change in Guizhou.The main findings are as follows:?1?The increase in temperature,the decrease in precipitation,and the increase in temperature and decrease in precipitation all have certain effects on the growth of U.,The increase in temperature promotes the division of U.cells,the total number of U.leaves and the root biomass increase significantly;The reduction of precipitation limits the growth and division of U.cells to a certain extent,and the total number of leaves and leaf biomass are significantly reduced;The increase in temperature exacerbates the inhibitory effect of reduced precipitation on U.,and root growth and root biomass accumulation are significantly restricted.?2?After increasing the temperature by 5°C,the net photosynthesis rate and transpiration rate of U.show an upward trend.Decrease and decrease;the increase in temperature aggravates the precipitation and reduces the degree of inhibition of the photosynthesis of U.,and the net photosynthetic rate decreases significantly.The increase in temperature is beneficial to the photosynthesis of U.;the decrease in precipitation makes the U.restricted by stomatal photosynthesis and therefore is suppressed;when the precipitation is reduced,the temperature increases and the water deficit is exacerbated.?3?The content of starch,proline and soluble protein in U.leaves showed an upward trend after the temperature increased;the decrease of precipitation caused U.to be subjected to a certain degree of osmotic stress.Starch,soluble sugar and proline in U.And the accumulation of soluble protein content can provide protection for U.;the increase in temperature aggravates the water loss caused by the reduction of precipitation.The content of starch,soluble sugar,proline and soluble protein in U.leaves increased first with the decrease of precipitation After the downward trend.The increase in temperature promotes the increase in the synthesis capacity of U.,the decrease in precipitation causes the starch to partially hydrolyze,and the content of osmotic substances increases to resist external stress.When the precipitation decreases,the increase in temperature exacerbates the degree of oxidative stress.The self-regulation ability of U.is disturbed,and the content of osmotic adjustment substance decreases.?4?The decrease in precipitation is not conducive to the stability of the cell membrane of U.With the decrease of precipitation,the MDA and O^2-contents of Uncaria macrophylla leaves show an increasing trend,and the degree of membrane lipid peroxidation increases;the increase in temperature exacerbates the decrease in precipitation.In the degree of oxidative stress of U.,the contents of MDA and O^2-in the leaves of U.increased significantly,and the activities of antioxidant enzymes SOD and POD were significantly enhanced.When the temperature increases,the content of superoxide anion free radicals and MDA in U.is low,and U.is in a good growth state;the reduction of precipitation exerts a certain stress on U.,but the relationship between the production of active oxygen and the balance of scavenging is maintained at a relatively high level.The steady state indicates that the reduction of precipitation caused the stress of U.to be within the adjustable range;the increase of temperature after the decrease of precipitation aggravated the external stress on the U.,the relationship between the generation of active oxygen and the elimination of the balance was destroyed,and the U.was damaged serious.?5?The increase of temperature and the change of precipitation have no significant effect on the content of N,P and K nutrients contained in U.leaves.The decrease of precipitation reduced the N,P,and K contents of U.to varying degrees;the increase in temperature was beneficial to the accumulation of P and K contents in Uncaria macrophylla leaves;when the temperature was increased,the decrease in precipitation was not conducive to the nutrients of U.The accumulation of content.?6?The increase of temperature and the change of precipitation have a significant effect on the secondary metabolites of U.The reduction of precipitation is beneficial to the accumulation of flavonoids,total alkaloids,uncariatine and isorhynchophylline in the leaves of U.;The cumulative amount of isorhynchophylline reached the maximum.When the precipitation was reduced to 75%,the increase of temperature caused the cumulative amount of flavonoids in U.leaves to reach the maximum.