Effects Of Drought Stress On Root Structure And Physiology Of Two Kinds Of Potentilla

There are two kinds of Potentilla:Potentilla ansrina and Potentilla bifurca var.labrata were used as experimental materials.Through the method of natural water control for drought treatment,the growth condition,microstructure,ultrastructure and physiological index of plant roots under different drought treatment conditions were measured,and the adaptability of two kinds of Potentilla under different drought stress was discussed and compared,which provided the basis for selecting drought resistant plants in arid areas and theoretical support for expanding the application scope of two kinds of plants.The main results are as follows:1.The changes of root system morphological characteristics of two kinds of Potentilla are related to the degree of drought.With the aggravation of drought stress,the total length,total surface area,volume and average ground diameter of roots increased gradually;the dry weight,root crown ratio and root weight density of roots increased first and then decreased;the specific root length of Potentilla anserina decreased first and then increased,while the specific root length of Potentilla bifurca var.labrata increased all the time.2.The anatomical structure of the two root systems of Potentilla were affected by drought stress.With the aggravation of drought degree,the primary xylem and primary phloem of two kinds of Potentilla had significant displacement,and the secondary xylem and secondary phloem had displacement and fracture phenomenon at the same time.Under the same stress time,the effect of drought on the root structure of Potentilla bifurca var.labrata was greater than that of Potentilla anserina.3.The ultrastructure of plant roots was affected by drought stress.When the drought stress increased gradually,the cell walls of the roots of the two plants became thinner,and even damaged under severe stress.The number of mitochondria decreased gradually until it disappeared,but the number and volume of starch granules were in direct proportion to the degree of drought.The vacuoles in the structure of Potentilla anserina gradually decreased to disappear,but there was no vacuole in the root system structure of Potentilla bifurca var.labrata,so the water storage capacity of the root system of Potentilla bifurca var.labrata was smaller than that of Potentilla anserina.4.The influence trend of drought stress on five physiological indexes of two kinds of Potentilla is basically the same.When the time of drought stress prolonged,the MDA content of the two kinds of Potentilla increased gradually.After 5 and 10 d of rehydration,they basically returned to normal state.After 15 and 20 d of rehydration,they recovered to a large extent,but after 25 d of rehydration,they could not recover.The proline content of Potentilla anserina increased first and then decreased.The proline content of Potentilla bifurca var.labrata increased all the time,and the increase of Potentilla bifurca var.labrata was less than that of Potentilla anserina After rehydration,the content in the early stage of drought recovered,but the higher content in the later stage recovered less.The content of soluble protein in two plants increased gradually,and the change range of Potentilla anserina was larger than that of Potentilla bifurca var.labrata.The content of SOD and POD increased at first and then decreased with the extension of time.After rehydrating,it was found that they would return to the original normal state after rehydration in the early stage of drought,but could not be restored in 25 d of drought.By comparing the changes of physiological indexes of two plants,it is found that the critical state of drought resistance of two kinds of Potentilla is 20 d,and the drought resistance of Potentilla anserina under the same stress is stronger than that of Potentilla bifurca var.labrata.