Study On A Technical System Of Tissue Culture And Rapid Propagation Of The S Series Dwarfing Rootstock Of Pear

Through the studies on regeneration of in vitro culture of S series dwarfing rootstock of pear, the proper explant induced directly and the time of induction were chosen, and die main influencing factors of multiplication ,rooting .training, transplanting and niicrografting were evaluated, At the same time, some improving methods were put forward. Technical system of tissue culture and rapid propagation of the S series dwarfing rootstock of pear was established. The main achievements were as follows:The survival rate of the shoot tip explant in March was higher than that in winter and April桱une, 1/3MS + 6-BA1.0 (mg/L, follows as the same) + IBA0.2 + GA31.0+ 2.5%sugar +0.65% agar was most suitable to initiatory culture of the explant. The browning of explant is relative to the PPO activity and the total phenol contents existed in the explant, The highest PPO activity occured in April, and the total phenol contents and browning rate are highest in May.MS+6-BA1.0+IBA0.2+GA30.1+2.5%sugar +0.65% agar was suitable to subculture of adventitious bud. The more of the subculture times, the higher of the coefficient of multiplication, The coefficient increased rapidly after the tenth subculture and decreased begun in the seventeenth subculture. 6-BA concentration under 2.0mg/L, GA3 concentration under 0.1 mg/L and use appropriative sealing material could improved the quality of adventitious shoot and overcome vitrification.Technical system of rooting of the adventitious shoots was established. Two-step-rooting method is better one-step-rooting method, That is, Firstly selecting the juvenile and vigorous shoots , Secondly culturing the shoots in the ASH medium with 2.0mg/L IBA for 7~9d in the darkness in order to promote the formation of primordium of root, then transfering the shoots into the ASH +vermiculite medium without IBA in the light. Adding 80~100mg/L trihydroxybenzene (PG) into the medium promoted on rooting with IBA, but had no effect on rooting without IBA. The more of the subcultural times, the41higher of the rooting ratio.The environmental conditions were main factors of training and transplanting of the rooting shoots. The rooting shoots must be trained for lOd in the light with the sealing material before transplanting , and then transferred into vermiculite medium with 90%~ 100% humidity , winding and lighting gradually after that, then the rooting shoots were transferred into the pots after 30d. Spring (April~May) is most suitable for the in vitro plantlet training and transplanting.The survival ratio was high when the shoots without rooting after induced in rooting medium were grafted on semi-wooden rootstock ofPyrus betulaefolia Bge. The technical system of tissue culture and rapid propagation of the S series dwarfing rootstock of pear was further perfected through the micrografting.