Effect Of Cypress Root Exudates On Fine Root Biomass,Morphology And Nutrient Of Eucalyptus And Toona Sinensis Seedlingsn

The decline of the productivity of the pure forest of Cupressus funebris in the hilly area of central Sichuan,China,and its low overall efficiency has become obstacles to forestry development.Coniferous and broad-leaved mixing is an effective method for the transformation of low-efficiency forests.When they are mixed,the root exudates of Cypress will have a significant impact on the soil environment and the fine roots of the mixed species,which will affect the growth of the entire plant and the productivity of the forest ecosystem.Eucalyptus and camphor trees are native broad-leaved species in the hilly area of central Sichuan Province,which have important ecological and economic values.Cupressus funebris cypress root exudate was applied to the seedlings of potted eucalyptus(Koelreuteria paniculata)and Toona sinensis to study the response of fine roots of eucalyptus and toona sinensis,and suitable tree species were selected for the transformation and sustainable management of low-efficiency forest of Cypress.for reference.In this experiment,the root exudates of annual cypress seedlings were extracted,and 5 concentrations(CK,1x,2x,4x,and 8x)were set to extract 1/12 of the root exudates of a cypress’ s rhizosphere soil or the corresponding The soil nutrients were set as x,once a month,for a total of 12 times,and applied to annual eucalyptus and sweet-smelling pot seedlings to determine the biomass and morphological characteristics of the fine roots of eucalyptus and toon(diameter,specific root length SRL,root length density RLD,specific surface area SSA,tissue density RTD),fine root nutrients(all N,all P,all K,Na,Ca,Mg).The consequence is as follows:(1)Overall,the effects of root secretions of Cypress were more significant on the fine root biomass of eucalyptus,and had no significant effect on 1-4 roots.The 1~5 roots of eucalyptus were all promoted at 1x,2x,and 4x,and began to inhibit at 8x.The 5th root of Toona sinensis showed promoting effect at low concentration(1x,2x)and inhibited at 4x and 8x.(2)The cedarwood root exudates had no effect on the diameter of the fine roots of eucalyptus,but also had a minor effect on the fine roots of the low root sequence(1~3)but had a significant effect on the 4th and 5th roots.SSA and RTD were less affected by each concentration of cypress wood exudates in this study.The response of SRL and RLD to root exudates showed different behavior in each order.The 8x concentration of cypress root exudates had inhibitory effects on the 4th and 5th roots of eucalyptus,and had no significant effect on the 1-3 roots.The rest of the concentrations had promotion effect on the rhythm of the saplings.The 1x and 2x cypress root exudates.The root sequence of the toona sinensis showed promotion of the SRL,4x and 8x had no significant effect on the root sequence.The 1x and 2x cypress root exudates mainly promoted RLD of 1-4 roots of Eucalyptus,inhibited 5 roots,8x inhibited roots 1 and 2;1x and 2x cypress root exuded to camphor The influence of root sequence RLD was not significant.4x showed a promoting effect on 1~4 grades,8x had a promoting effect on 3rd and 4th grade roots,and had no effect on other root sequences.(3)The cypress root exudates 1x and 2x only promoted the total N content of eucalyptus grade 1~3 roots when it was applied to eucalyptus,toona sinensis,and 4x,and inhibited the 1~3 grade roots of eucalyptus at 8x.The total P content of the fine roots of eucalyptus showed a promoting effect on the total P content of the fine roots of eucalyptus.The total P content of each order of the toon was increased by 1x and 2x.However,the 3rd roots of eucalyptus were reduced at 4x and 8x.The full P content of roots from 1 to 3 roots of Toona sinensis.1x Cypress root exudates increased the total K content of eucalyptus primary roots and 1,3,and 5 roots of citron,2x had a promoting effect on eucalyptus and citron,and 4x increased eucalyptus primary roots and Shannon 2,3 roots.The K content decreased the total K content of the 5th root,8x had no effect on the root order of the Eucalyptus,and inhibited the 4th and 5th roots of the camphor.The concentration of cypress root exudates of each concentration had little effect on the Na content of the fine roots of eucalyptus and citron.The Ca content in the tertiary roots of Toona sinensis and Eucalyptus was most sensitive to the concentration of the root exudates of cypress trees.The 1x,2x,and 4x cypress root exudates increased the Ca content of the fine roots of the eucalyptus tree,and began to inhibit the banyan tree roots at 8x.Effects;1x,2x increased the Ca content of the fine roots of Toona sinensis,inhibited the 1-to-3 degree roots of Toona sinensis at 8x.1x root exudates promoted the absorption of Mg3 roots and 2x to 3rd and 5th root Mg,respectively.4x and 8x root exudates had no effect on the Mg content of the fine roots of Cinnamomum camphora.1x had the same effect on Mg content of 1~5 roots of Cinnamomum camphora.All of them have a significant promoting effect,and then the effect of promoting the concentration of root exudates gradually decreases until the level of 2~4 root Mg is reduced at 8x.In summary,the fine root diameter,specific surface area,tissue density,and Na content were all less affected by the concentrations of cypress root exudates in each test.The effects of cedarwood root exudates on the specific root length,root length density,total N,total P,total K,Ca,and Mg content of the fine roots of eucalyptus and toona sinensis showed that low concentrations promoted the increase and high concentrations had inhibitory effects.