Studies On Transplanting Physiology And Rapid Propagation Of Apple Rootstock M9and M26

In recent years, apple dwarf rootstock has been widely used around the world due to itssmall tree, suitable for close planting, early fruiting, high productivity, and excellent fruitquality.In this study, apple rootstocks M9and M26were employed as the test material, wefocused on its rapid propagation and tissue culture, transplanting and the physiologicalchanges in the process of transplanting. At the same time, we studied adventitious rootformation and development process of apple rootstocks M9and M26by using paraffinmethod, aiming to improve the rooting and survival percentage of apple rootstock plantlets,thus, bettering the apple dwarf rootstocks in vitro rapid propagation system. The best mediumfor vitro shoots of apple rootstock M9and M26wasThe main results are as follows:1. We established apple rootstock M9and M26rapid propagation system.The bestmedium for vitro shoots of apple rootstock M9and M26was MS+6-BA1.0mg/L+NAA0.5mg/L. In terms of suitable proliferation medium, Apple rootstocks M9and M26wasMS+6-BA1.0mg/L+IBA0.1mg/L.The Effective number of new shoots for apple rootstockM9and M26were6.4shoots/plant and6.8shoots/plant respectively. Both of the new budswere in good condition. The proper rooting medium for apple rootstock M9and M26was1/2MS+IBA0.3mg/L+NAA0.1mg/L, with its rooting percentage82.4%and85.6%respectively.2. From the perspective of anatomy observation, the adventitious roots of apple rootstockM9originated from junction of vascular cambium and ray. As for the apple rootstock M26,the adventitious root primordial only occurred in parenchyma cells of vascular cambium parts.The rooting process of M9can be divided into:（1） period of cells forming layer differentiation;（2）period of adventitious root primordial;（3）period of adventitious differentiation faormtion.3. The suitable acclimatization conditions for apple rootstock M9and M26tissue cultureseedlings were as follows: root length over3cm,root number over4cm,leaves number over4,closed bottle seedling for6days, opened bottle seedling3to6days,3/5field soil+2/5 vermiculite as substrate. Survival rates of transplanting for apple rootstock M9and M26were72.2%and72.3%respectively.4. The chlorophyll content of apple rootstock M9and M26decreased and then increasedin the process of acclimatization, from9.92and9.73mg/g.FW on0day to14.17and12.52mg/g.FW on50days of acclimatization. The open degree of stomata applerootstock M9and M26declined with the acclimatization time increased, from0.86and0.84on0day to0.56and0.51on50days of acclimatization. The net photosynthetic rate,intercellular CO2concentration of apple rootstock M9and M26rose with the theacclimatization time increased, net photosynthetic ranged from-3.93and-3.48umol.m^-2.s^-1on0day to1.83and1.75umol.m^-2.s^-1on30days of acclimatization，intercellular CO2concentration ranged from678.23and665.25umol.mol-1on0day,1026.80and996.21umol.mol-1on30days of acclimatization. The stomatal conductance of apple rootstock M9and M26decreased with with the acclimatization time increased, from89.45and86.33mmol.m^-2.s^-1on0day48.69and42.15mmol.m^-2.s^-1on30days of acclimatization. Thesephysiological changes demonstrated the transition of plantlets from heterotrophic toautotrophic state.