Waterlogging Resistance And Effects Of Salt-waterlogging Interaction On The Growth Of Kosteletzkya Virginica

Water is the basis for plants to carry out their life activities smoothly and occupies an important position in the survival of plants,but too much water will affect the normal growth of plants.The rainfall distribution in China is uneven,and most of the land is seriously flooded.Therefore,it is of great social and economic benefit to cultivate plants suitable for growing in flood-prone areas.In this paper,we explored the causes of physiological and biochemical changes and analyzed the mechanism of resistance of kosteletzkya virginica through the waterlogging and salt-waterlogging interaction expriments.The results are as follows:1.Study on the waterlogging resistance of kosteletzkya virginica seedlings.Waterlogging stress significantly decreased the growth of plant height and biomass of kosteletzkya virginica.The degree of depression was greater and greater as the continuation of waterlogging,after 18 days,the tendeney to be stable.The plants were still able to maintain their survival after 24 days,indicating that kosteletzkya virginica has strong resistance to waterlogging.The activity of SOD and CAT increased under waterlogging,yet the content of MDA and O₂^.-still gradually increased simultaneously.At the same time,waterlogging limited photosynthetic rate.With the time course of waterlogging,Pn and Gs of seedlings continued to decrease,and Ci showed a continuous increase trend.In the short time of waterlogging,anaerobic respiration increased and the activity of ADH increased.However,with the prolongation of waterlogging,anaerobic respiration decreased and ADH activity decreased.Waterlogging destroyed the PS? photochemical structure of seedlings,Fv/Fm,?PS? and qP all showed a decreasing trend.As the waterlogging continued,they decreased slowly.Waterlogging affected the formation of adventitious roots.The longer the time,the more adventitious roots and the bigger root mean diameter.After analysis,forming adventitious root is one of the important mechanisms for waterlogging adaptation.2.Sensitivity to waterlogging in different seedling periods.In this part of the experiment,the biomass of different periods of plants was inhibited by waterlogging.The proportion of underground/above-ground parts increased,and the proportion of 2-leaf age was the highest and 6-leaf age was the smallest.The activity of SOD and CAT,as well as the content of MDA and O₂^.-were gradually increased of different seedling ages under waterlogging.However,the increase in the biomass,the activity of SOD and CAT as well as the content of MDA and O₂^.-of different periods all differ with the extent of waterlogging,and is different.Under waterlogging,photosynthesis of seedlings was inhibited,and the photosynthetic apparatus function was impaired.The main manifestations were the sharp decline of Pn,Gs,Fv/Fm,?PS?,and qP in early processing,and they were stable in later stages,and there were differences periods.The treatment also induced the formation of adventitious roots.With the extension of time,the number of adventitious roots induced was different.The plant had the greatest ability to resist waterlogging at the age of 2 leaves,and the least at 6 leaves.Through the paraffin section of roots,it was found that the cortex parenchyma cells became larger and dissolved in the main root under waterlogging.As the waterlogging prolonged,the dissolved parts formed a ventilation gap.The induction of adventitious roots founded that the adventitious root epidermal cells were few and thin,with the parenchyma cells increased in size,mostly oval and round,with the extension of treatment time,the parenchyma cells showed dissoluion,the same as the main root cortex.3.Study on the tolerance and recovery of kosteletzkya virginica seedlings at different times of submergence.Submergence significantly depressed the growth of plant plant height and biomass of kosteletzkya virginica.With the continuation of submergence,the degree of inhibition increased,and it was difficult to recover after 9 days of submergence.We can concluded that 9 days of submerge is the dead line for kosteletzkya virginica.Under submergence,the plants showed a dramatic increase in the activities of antioxidant enzymes such as SOD and CAT together with the contents of MDA and O₂^.-.At the same time,the Pn,Gs,Fv/Fm,?PS?,and qP are decresed.After 9 days,the Pn and Fv/Fm were greatly reduced,indicating that the plant PS? was inhibited and the reaction center was irreversibly damaged or reversibly inactivated.A small amount of adventitious root formation was induced under submerge.Furthermore,COX is inhibited and the AOX pathway is enhanced;upon recovery,the cytochrome pathway is restored and the alternate oxidase pathway is inhibited.However,the alternate oxidase pathway was not inhibited but was enhanced after 9 days recoverry.4.The effects of salt and waterlogging interaction on the resistance of kosteletzkya virginica.In this experiment,waterlogging,salt stress,and salt-waterlogging all affected the growth of kosteletzkya virginica.Under stress,the activities of antioxidant enzymes such as SOD and CAT increased,the contents of MDA and O₂^.-increased,the content of chlorophyll decreased sharply,the content of Na⁺in leaves and roots increased,the content of K⁺decreased,and the Pn and Gs decreased drastically.Fv/Fm,?PS?,and qP decreased,and root length decreased.But under different stress,their relative increase rate and relative decrease rate were different.The overall performance was that the physiological and biochemical effects of salt-waterlogging interaction on plants were greater than that of salt stress and waterlogging.It showed that the salt-waterlogging interaction stress exerted an additive effect on the damage of plants.In the aspect of root formation,waterlogging induced a large number of adventitious root formation,but there was no or few adventitious roots in the salt stress and salt-waterlogging interaction.