Studies On The Effects Of Several Exogenous Substances On Plant Physiology By Mitigating Environmental Stress

Plant growth and development will be subjected to a variety of environmental stresses,including heavy metal stress,damage,drought,high salt,temperature?high and low temperature?and light changes,as well as pathogens and insect pests attack and so on.In order to alleviate the harmful effects of environmental stress on plants,we study the protective effects of exogenous additive on plants.In this paper,we first used rape and Angelica sinensis seedlings as materials to study the toxic effects of Cu stress on plants and the abatement of attapulgite clay on Cu.Then,the response of exogenous Salicylic acid to low concentration Cu stress on PS?was studied by using Angelica sinensis seedlings as material.Finally,the response of exogenous ATP to PS?under drought and low temperature stress was studied.The results were as follows:1.With the increase of exogenous Cu concentration,the PSII Photochemistry and chlorophyll content in rape seedling leaves,but the content of Cu in plant,soluble protein,the production level of reactive oxygen species?ROS?and the activity of antioxidant enzymes in seedling leaves increased.In the absence of Cu stress,the physiological indexes of rape seedlings grown in vermiculite and attapulgite clay?AC?/vermiculite?volume ratio of 1:80,1:50 or 1:30?were not significantly different.For rape,the volume ratio of AC/vermiculite at 1:50 to 1:30 was the best proportion to alleviate the physiological effects of short-term Cu stress.In the same way,as far as Angelica sinensis,the volume ratio of AC/vermiculite at 1:70 to 1:50 was the best proportion to alleviate the physiological effects of short-term Cu stress.The above results show that the proper addition of AC in the medium can reduce the physiological stress of the plant seedlings in the growth matrix.2.The Angelica sinensis seedlings was treated with 5 mmol L^-11 CuCl₂ for 24 h,48 h and 72 h,the chlorophyll contents,Y???,ETR and Fv?/Fm?of Angelica sinensis seedlings decreased significantly with the prolongation of stress time compared with the control,and the chlorophyll content of the seedlings of Angelica sinensis decreased significantly with the prolongation of stress time,and the qN increased significantly compared with the control.At the same time of CuCl₂ stress,the chlorophyll contents,Y???,ETR and Fv?/Fm?in leaves of Angelica sinensis seedlings treated with Salicylic acid were higher than those of leaves without SA treatment increased,but the qN decreased.The results indicated that Cu stress decreased chlorophyll synthesis and photochemical efficiency of Angelica sinensis seedlings,but the application of salicylic acid could effectively alleviate the adverse effects caused by Cu stress.3.Both drought and low temperature stress can cause the Y???,ETR,qP and chlorophyll content to be significantly reduced,while also causing a significant increase in qN.The application of exogenous ATP alleviated the decrease of Y???,ETR,qP and chlorophyll content in leaves of Angelica sinensis under drought and low temperature stress,and also eliminated the increase of qN.The results indicated that exogenous ATP could effectively increase the open ratio of PS?reaction centers,the electron transfer rate and light energy conversion efficiency of Angelica sinensis under drought and low temperature stress.It was beneficial to enhance the chlorophyll synthesis of Angelica sinensis seedlings and the adaptability of PS?to drought and low temperature stress.In conclusion,in view of different environmental stresses,the toxic effect of environmental stress on plants can be alleviated to a certain extent by adding or spraying exogenous additive in the culture medium or on the leaves of plants.