Characteristics Of Growth Physiology And Evaluation Of Stress Resistance Of Typical Sand-fixing Plant Roots After Exposure

Soil wind erosion is the main cause of root system exposure in desert or sandy land,and it is also the primary link in the process of desertification.The study on the physiology and growth of the seedlings and adult plants of the sand-fixing plants after root exposure can provide a reference for improving the conservation and management of direct seeding and aerial sowing afforestation and sand-fixing plants in the sandy area.In this experiment,the typical sand-fixing plants in Ningxia were used as research objects.Three root gradient exposure experiments were carried out on their seedlings and adult plants respectively.The growth and physiological response characteristics of roots after exposure were analyzed,and their growth physiological indexes were used.The stress resistance evaluation results are as follows:1.Physiological response characteristics of roots exposed to Hedysarum scoparium and Caragana korshinskii seedlings:after exposure to roots,the growth of malondialdehyde of Hedysarum scoparium was higher than that of Caragana korshinskii,and the chlorophyll a/b of Hedysarum scoparium was significantly lower than that of the control,resulting in photosynthetic rate.Below the control,the growth of the Hedysarum scoparium was inhibited,and the root treatment did not significantly inhibit the growth of Caragana korshinskii.Both the antioxidant enzyme system and the osmotic adjustment system were involved in the regulation,and the peroxidase POD(Hedysarum scoparium)and catalase CAT(Caragana korshinskii)were used to remove the peroxide from the cells,respectively.Increased proline Pro and soluble sugar SSC(both of which are elevated in the Caragana korshinskii,and only the proline of the Hedysarum coparium is elevated)to resist water stress caused by root exposure.It can be seen that under the same root exposure ratio,the adaptability of Caragana korshinskii may be higher than that of Hedysarum scoparium.2.Response characteristics of adult plants after root exposure:The results of covariance analysis showed that the physiological indexes of four kinds of sand-fixing plants,Hedysarum scoparium F.,Caragana korshinskii K.,Artemisia ordosica K.,and Calligonum mongolicum T.,were not significant after treatment.P>0.05),but the three treatment gradients(10 cm,20 cm,30 cm)had different significant effects on the physiological indexes of the four plants(P<0.05,the same below).(1)The proline and soluble sugars and catalase(CAT)of Hedysarum scoparium F.were significantly affected by root exposure,that is,Hedysarum scoparium F.also enabled osmotic adjustment substances and antioxidant enzymes to resist stress,but compared with the seedlings,The physiological indicators that are enabled are different.(2)The chlorophyll A and carotenoids of the roots of Caragana korshinskii K.showed the first change and then the increase(on the 7th day and the 14th day,and the 21st day to the control level).The enzymes(peroxidase POD and catalase CAT)have a tendency to rise first and then fall.Soluble sugar SSC also has an upward trend(3)The photosynthetic pigment content of the roots of Artemisia ordosica K.was not significantly changed(P>0.05),the proline Pro content was increased,and the activity of peroxidase POD and catalase CAT in the antioxidant enzyme system was significantly enhanced(P<0.05),that is,the antioxidant enzyme system cleared the oxides in time to prevent oxidation of the cell membrane,so there was no significant difference between the malondialdehyde content and the control.(4)The chlorophyll content of the leaves of Calligonum mongolicum T.leaves decreased after root exposure.The length and leaf number of exposed leaves of 30 cm roots were lower than that of the control.Catalase was involved in physiological regulation,and the osmotic adjustment system did not respond to root exposure.3.Comprehensive evaluation of stress resistance after root exposure:Hedysarum scoparium and Artemisia ordosica were classified into one type of strong resistance to root exposure;Caragana korshinskii was moderately resistant to root exposure;Calligonum mongolicum is weak resistant to root exposure.