Effects Of Intergeneric Grafting Of Schisandraceae Plants On Rootstock Growth And Physiological Characteristics

Schisandraceae plants are concentrated in China and rich in resources.Their roots,stems,leaves and fruits can be used as medicine to treat a variety of diseases with complete efficacy.Kadsura coccinea(Lem.)A.C.Smith and Schisandra sphenanthera rehd.etwils.belong to Kadsura Kaempf.ex juss.and Schisandra Michx.of Schisandraceae respectively,which are economic forest trees with important medicinal value.Grafting is widely used to increase the productivity of plants by giving them resistance.However,there were few studies on the grafting of Schisandraceae plants at present.The existing studies only explored the effect of rootstock on scion,and lacked the effect of scion on rootstock,leading to the unclear interaction mechanism of rootstock and scion growth and development.In this study,Kadsura coccinea(K)and Schisandra sphenanthera(S)were used as scions and rootstocks for intergeneric grafting using the approach grafting,in which the heterologous grafting combinations(K/S,S/K,scions/rootstocks)were taken as the experimental group and the self-grafting combinations(S/S,K/K,scions/rootstocks)were taken as the control group.The root morphology,anatomical structure and physiological characteristics of rootstocks from different grafting combinations were compared and analyzed,aiming to explore the effects of intergeneric grafting of Schisandraceae on the rootstocks,so as to provide a preliminary basis for further research on the rootstock-scion interaction mechanism.The main results were as follo(wls):Effect of scion on root morphology of rootstock after intergeneric grafting.Compared with the control,the total root length,root volume,root tips and root biomass of K/S and S/K were significantly decreased at the late stage of grafting,while the specific root length and specific surface area were significantly increased at the early stage of grafting.For the root average diameter and root surface area,K/S was increased while S/K was decreased,and they all changed significantly at the late stage of grafting.The above morphological indexes were significantly increased or decreased by about 10%as compared with those of the control.In addition,root morphological changes of K/S were mainly in the 0-5 cm soil depth,while root morphological changes of S/K were mainly in the 5-10 cm soil depth.(2)Effect of scion on anatomical structure of rootstock after intergeneric grafting.Compared with the control,the root cross section and xylem areas of K/S increased by about 30%in the first,second and third order roots.However,the root cross section and xylem area of S/K were increased in the first order root,increasing significantly by 24.6%and 73.3%,respectively,and decreased in the second and third order roots,with the xylem area changed significantly by 48%and 60.9%,respectively.The cortex(thickness and proportion)of K/S decreased in the first order root and increased in the second and third order roots,but the changes in the vascular bundle(diameter and proportion)in each order roots were just the opposite to the cortex,and they were significantly increased or decreased by about 40%compared with the control at the late stage of grafting.The cortex(thickness and proportion)and vascular bundle(diameter and proportion)of S/K were increased and decreased in the first,second and third order roots,and significantly different from those of the control in the second and third order roots at the early stage of grafting,with increases and decreases of about 30%respectively.(3)Effect of scion on physiological characteristics of rootstock after intergeneric grafting.The contents of indoleacetic acid(IAA),zein(ZR)and the ratios of IAA/ABA,ZR/ABA and(IAA+ZR+GA3)/ABA in root of K/S and S/K were significantly lower than those of the control at 10 d to 50 d after grafting,while the contents of gibberellin(GA3),abscisic acid(ABA)and the ratio of GA3/AB A were significantly higher than those of the control.However,changes in the contents and ratios of endogenous hormones in different grafted combinations took a turning point at 70d,which was consistent with the changing rules of root morphological indicators among the combinations.In addition,K/S and S/K had lower root activity and soluble sugar content compared with the control,and the root activity was most significantly changed at 30d after grafting,which was reduced by about 50%,while the soluble sugar content of K/S and S/K was significantly reduced by 26%and 41.6%,respectively.For soluble protein and malondialdehyde(MDA)content,K/S had no significant difference with the control,while S/K was significantly lower than the control by 11%and significantly higher than the control by 83.6%,respectively.For superoxide dismutase(SOD)activity,K/S was significantly higher than that of the control by 17.8%,while S/K was significantly lower than that of the control by 35.6%.