These studies were conducted to determine the most effective methods for increasing shoot elongation during the initial proliferation stage of micropropagation in two dwarfing apple, Malus ×domestica (Borkh.), rootstock cultivars. Several experiments were conducted to compare explant collection date, exposure to chilling (5 ± 1 °C) temperatures, and varying concentrations of plant growth regulators in Murashige and Skoog (MS) media. Microshoot growth of ‘Geneva 41’ (‘G.41’) was very low and unaffected by chilling duration from 0 to 8 weeks or by gibberellic acid (GA3) concentration from 0 to 1.0 mg·L−1, but was improved by an additional subculture which increased shoot length from 1 to 15 mm. In ‘Geneva 30’ (‘G.30’), shoot elongation was most affected by date, chilling explants, and by optimizing cytokinin concentration and type. Explant collection date in April increased shoot growth compared with August or November. Microshoot growth of ‘G.30’ was increased by chilling nodal explants for 4 and 6 weeks when explants were collected in August and November, but not in April. Eight weeks chilling was detrimental for explants collected in April, and generally had little or no effect with August and November. The cytokinin 6-benzylaminopurine (BA) increased shoot number to a greater extent than thidiazuron (TDZ) or zeatin (ZT), and was also more effective for increasing shoot elongation with concentrations of 0 to 2.0 mg·L−1. In ‘G.30’, GA3 increased shoot growth at the optimum concentration of BA, but not with lower concentrations. ‘G.30’ microshoots were fewer and shorter with 24-epi-brassinolide (EBR) at concentrations of 0.1 and 1.0 mg·L−1. Chemical names: N-phenyl-N’-(1,2,3-thiadiazol-5-yl)urea (TDZ), 6-(4-hydroxy-3-methylbut-2-enylamino)purine (ZT).
This project was funded in part by a grant from the Maine Agricultural Center and by the USDA National Institute of Food and Agriculture Hatch project NC140.
Mention of a trademark, proprietary product, or vendor does not constitute a guarantee or warranty of the product, and does not imply its approval to the exclusion of other products that also may be suitable. Maine Ag. and Forest Exp. Stn. no. 3479.
BouzaL.JacquesM.MazièreY.ArnaudY.1992In vitro propagation of Prunus tenella Batsch. cv. ‘Firehill’: Control of vitrification; increase of the multiplication rate and growth by chillingSci. Hort.52143155
Bouza,L.Jacques,M.Mazière,Y.Arnaud,Y.1992In vitro propagation of Prunus tenella Batsch. cv. ‘Firehill’: Control of vitrification; increase of the multiplication rate and growth by chilling52143155)| false
SchaeferS.MedeiroS.A.RamirezJ.A.GalagovskyL.R.Pereira-NettoA.B.2002Brassinosteroid-driven enhancement of the in vitro multiplication rate for the marubakaido apple rootstock [Malus prunifolia (Willd.) Borkh.]Plant Cell Rpt.2010931097
Schaefer,S.Medeiro,S.A.Ramirez,J.A.Galagovsky,L.R.Pereira-Netto,A.B.2002Brassinosteroid-driven enhancement of the in vitro multiplication rate for the marubakaido apple rootstock [Malus prunifolia (Willd.) Borkh.]2010931097)| false