Studies On Response Of Piriformospora Indica To Drought Resistance In Paulownia Elongata

Drought and water scarcity have become major limiting factors affecting agricultural and forestry production and the sustainable development of gardens.Water stress leads to reduced plant survival,inhibits the growth of plant height,diameter at breast height,and biomass,seriously affects the species diversity of garden plants,and hinders the construction and development of urban garden vegetation landscapes in arid areas.In this thesis,the common Paulownia elongata was chosen as the study material.Pot experiments were conducted on them under different water stress treatments(70%～75%,40%～45%,and 20%～25% of the field water capacity).To study the effects of P.indica on the growth and physiological indexes of Paulownia elongata under different drought conditions,and to clarify the response mechanism of inoculation of P.indica on drought resistance and growth promotion of Paulownia elongata.The results show that:(1)The experimental results showed that P.indica was able to colonize the roots of Paulownia elongata successfully under different water treatment conditions and formed a good symbiotic relationship with Paulownia elongata.The mycorrhizal infestation rate showed a gradual decrease with the decrease of relative soil water content,which was 25.3%,18.6%,and 17.3% respectively.(2)Inoculation of P.indica could promote the growth of Paulownia elongata and increase their biomass significantly.Under normal water supply and moderate drought stress,plant height increased by 3.5% and 7.15%,aboveground biomass increased by 37.16% and 35.21%,belowground biomass increased by 10.36% and 1.05%,and total biomass increased by29.94% and 27.38%,respectively,compared with the control.Inoculation with P.indica reduced leaf damage and alleviated the growth inhibition of P.indica under drought stress.In addition,inoculation with P.indica could provide sufficient water supply to the host plant to ensure the growth activity of the host paulownia,improve the drought resistance of paulownia,and promote plant growth;meanwhile,under severe drought conditions,P.indica could keep the host plant with relatively sufficient water supply to maintain relatively normal physiological activities and keep the plant leaves healthy.(3)The study showed that P.indica could increase the net photosynthetic rate of Paulownia elongata under various water conditions,increase the transpiration rate,intercellular carbon dioxide concentration,and stomatal conductance under normal water and moderate drought conditions,promote the water utilization rate of Paulownia elongata under drought stress conditions,and increase the accumulation of biomass.(4)The Chlorophyll of Paulownia elongata increased first and then decreased with the aggravation of drought stress.The Chlorophyll a and Chlorophyll b of Paulownia elongata could be increased by P.indica under all water conditions.The total chlorophyll content increased by 4.39%,43.06%,and 69.01%,respectively,under each moisture condition compared with the control.(5)Inoculation of P.indica could improve the drought resistance physiological of Paulownia elongata.With the increase of drought stress,the SOD enzyme in Paulownia elongata increased gradually.Under all water conditions,the SOD enzyme of inoculation P.indica plant was higher than that of the control,and the activities of SP and POD enzyme were higher than that of the control under normal water and moderate drought conditions.Therefore,P.indica was able to alleviate the damage caused by drought stress and promote the growth of Paulownia elongata of P.indica by improving cellular osmoregulation and enhancing the antioxidant defense system,thus reducing oxidative damage.In conclusion,P.indica can significantly promote the growth of Paulownia elongata under normal water supply and moderate drought stress.The correlation analysis showed that the growth rate of P.indica plant height was significantly and positively correlated with transpiration rate and negatively correlated with SOD enzyme,and the relative leaf water content was significantly and positively correlated with above-ground dry weight,total dry weight,and transpiration rate,while the growth rate of control plant height was not significantly correlated with transpiration rate and SOD enzyme,and the relative leaf water content was not significantly correlated with above-ground dry weight,total dry weight,and transpiration rate.There was no significant correlation between relative leaf water content and aboveground dry weight,total dry weight,and transpiration rate.The two-way ANOVA showed that inoculation of P.indica significantly increased the stomatal conductance,SOD enzyme,and chlorophyll content of P.indica leaves and significantly increased the aboveground dry weight and total dry weight of P.indica Paulownia elongata compared with the control,indicating that P.indica can improve the adaptability of P.indica plant under drought stress by increasing the stomatal conductance,SOD enzyme and chlorophyll content of P.indica leaves,and improve the drought resistance of Paulownia elongata.