In vitro multiplication of peach rootstocks

The leaf yellowing and senescence during micro-propagation reduces the shoot proliferation rates with every sub-culture in peach rootstock (Prunus spp.). The effect of culture media and supplements on the proliferation of cultures during the micro-propagation of two peach rootstocks ‘Sharbati’ and ‘Flordaguard’ was studied. In both Prunus genotypes, the proliferated cultures decreased from 77.3% and 67.0 % after the first sub-culture to 35.3 % and 27.3 % after the third sub-culture in ‘Sharbati’ and ‘Flordaguard’, respectively. QL medium significantly improved the proportion of proliferated cultures over MS, WPM, DKW and the modified MS media. The highest proliferated cultures (79.0% and 70.7%) and shoot number per culture (4.2 and 3.7) were recorded after the third subculture, in ‘Sharbati’ and ‘Flordaguard’, respectively with QL medium. Both the rootstocks varied in their response to iron chelates. The higher proliferation rates were obtained with MS medium by substituting Fe-EDTA (0.1 mM) with Fe-EDDHA (0.1-0.3 mM) in ‘Sharbati’ and with Fe-Na EDTA (0.1 mM) in ‘Flordaguard’. In‘Sharbati’, the highest proliferated cultures (44.3%) after the third subculture were observed with Fe-EDDHA (0.3 mM). In ‘Flordaguard’, the highest proportion of proliferated cultures (45%) after the third subculture was recorded with Fe-Na EDTA (0.1 mM). Adding silver nitrate (3 mM) improved the shoot proliferation rates to the highest levels (63% and 51%) after third subculture in ‘Sharbati’ and ‘Flordaguard’, respectively. The highest rooting (34.3% and 38.0%) and number of roots per shoot (2.2 and 2.5) were recorded with 3.75 mM of IBA in ‘Sharbati’ and ‘Flordaguard’, respectively.