Study On Micro-cutting Of Populu Stremula×P.tremuloides And Its Rooting Mechanism

Taking Populustremula×P.tremuloides shoots as experiment materials,we have studied propagation of the Populustremula×Ptremuloides cutting. For discussing the mechanism of rooting occident of the Populustremula×P.tremuloides shoots, cutting' nutrients, rooting related enzymes, endogenous hormones were measured:anatomy analysis was taken.Orthogonal experiments indicated that shoots soaked with NAA100mg/L for 15 minutes is the best treatment combinations.Shoots soaked with NAA100mg/L for 15 minutes, the rooting rate can achieved 78%. Different stems from the same branch were choosed to experiment. Result show that the rooting of top segments of the stem was highest.It's the best cutting materials. Cutting experiment was taken form March until July, The rooting rate of Populustremula×Ptremuloides was higher from March to June(reach55%). April is the best cutting season, and in April cuttings rooting rate is the highest, reach 81.7%.Stems soaked in NAA100ppm for 15min used for research object to study rooting mechanism as stems soaked in water for 30min as control.The results show the content of soluble protein has declined during all the rooting process. The content of soluble sugar was not change in the induction stage,but it sharp rised in the initiationand stage,and it preserve high level until adventitious roots formation. The contion of the reducing sugar was sharp rised in the induction stage,and it woud be sharp declined in the initiationand stage and expression stage.The content of IAAO and POD increased in the stage of root original base infancy and root original base breakthrough epidermis after soaked in NAA.It can reduce the content of IAA and the low level of IAA is useful for the root primordium formation. Meanwhile the content of PPO (0-9 days) continue to rise, the content of PPO increased benefit to the IAA and phenolic compounds combining, generating rooting compound. Visible,the activity of the POD, PPO, IAAO are rising at the initiation stage, it is benefit for the root's formation. Analysis the change of hormones contents in the rooting show that the value of IAA/ABA increases can be considered as the signal of the rooting. And the decreases can be considered as a symbol of rooting finish. After the treatment with NAA, the value of ZR/IAA in the cuttings is low than control in the initiation stage which benefit for the rooting. GA, ZR can promote the formation of adventitious roots.Through anatomy analysis, There was three stages in the adventitious roots forming (induction, initiationand,expression).Induction stage is form day 0 to day 6,and some cambial zone and adjacent phloem cells became densecytoplasm, nuclei with prominent nucleoli and the first cell divisions were observed at day6. Initiationand stage is form day6 to day9, Identifiable root primordia witha conical shape and several cell layers were present at day 9. Expression stage is form day9 until day 15. Roots with organized tissue system emerged from the stem 15 days after the root induction treatment.