Responses Of Ecophysiological Characteristics Of Robinia Pseudoacatcia Seedlings To Different Precipitation Intensities And Frequencies

Water is one of the key factors affecting plant growth.Climate change has led to a worldwide redistribution of precipitation,the changes in precipitation intensity and frequencies.The number of summer rainstorms is reducedin China,with longer and stronger precipitation scale.Therefore,it is important to explore the effects of different drought stress patterns and drought rehydration on their physiological characteristics at different stages of seedling growth.Understanding the mechanism for trees to cope with drought is the key to predicting developing trend of forest ecosystems in future climatic conditions.The study of the effects of precipitation on plants will help to understand the coordinated development of plants under the conditions of future climate change and the response mechanism of trees to different drought stress and pattern.Robinia pseudoacacia L is widely considered as a drought-resistant tree species,and its research on its drought resistance is mainly to explore the difference between the different precipitation intensity,and it is a kind of drought-resistant tree species.And there is little research on the difference of R.pseudoacacia growth among different precipitation frequencies.And the frequencies of precipitation in the early growth of seedlings for plant physiological traits also have a very important impact.The effects of different precipitation frequencies on the growth of R.pseudoacacia under different precipitation intensities can reveal the response mechanism of R.pseudoacacia to different drought stress patterns.Different precipitation conditionsnot only affect the plant growth,but also on the plant’s drought resistance and its recovery ability after the impact of water.The difference between drought resistance and recovery ability of R.pseudoacacia seedlings grown under different precipitation backgrounds is helpful to understand the response mechanism of warm temperate vegetation to different precipitation changes R.pseudoacacia in different stages of growth season hanging the background of the vegetation restoration model to provide the basis.This experiment was divided into two parts:drought experiment and rehydration experiment.The annual rainfall intensity of three precipitation intensity and three precipitation frequencies were set up in the drought part,and the experiment was carried out for 60 days.The rehydration section is set up with two precipitation intensities and three precipitation frequencies of the cross gradient of the precipitation background,a drought stress pattern.The experiment is divided into three stages:the adaptation stage,the drought stage and the rehydration stage.The experiment is carried out for 60 days.The growth rate was reflected by the morphological index,biomass,gas exchange and chlorophyll content,and the growth rate curve was plotted by morphological index.In the drought experiment,it was found that the growth indexes of R.pseudoacacia showed a decreasing trend and the growth rate slowed down with the decrease of precipitation intensity and frequencies.However,under different precipitation intensity conditions,the difference between the different precipitation frequencies is different.Under the condition of high intensity precipitation,the growth status of R.pseudoacacia between different precipitation frequencies is quite different,and the difference of the growth status of R.pseudoacacia with different precipitation frequencies is low under low rainfall,and the difference is most The growth status of R.pseudoacacia was different under the high frequencies precipitation condition,and the difference was different under the low frequencies precipitation condition and the plant growth status among the different precipitation intensities was the smallest under the medium frequencies precipitation condition.Medium intensity or moderate frequencies of precipitation conditions below the low intensity or low frequencies of precipitation under the conditions of the plant.In the rehydration.experiment,it was found that there were no significant differences in morphological indexes between the six seedlings during the three precipitation stages,especially the difference between the diameter and the number of leaflets.The growth monitoring of the morphological indexes showed that the change of the growth rate had a certain delay effect with the change of precipitation conditions.Plants in the midst of moderate precipitation showed a strong ability to adapt to drought and recovery after rehydration.There was no significant difference in chlorophyll content between the six groups.