In vitro propagation of the PR 204/84 (Prunus persica × P. amygdalus) rootstock: Axillary shoot production and rhizogenesis

Abstract

PR 204/84 rootstock (peach × almond) is a promising alternative to GF 677 rootstock for peach (Prunus persica) trees. The present study was the first attempt for its micropropagation. Research was carried out regarding axillary shoot production and root initiation responses. 6-benzylaminopurine (BAP) at concentrations 2 and 4 μM resulted in a high yield of axillary shoots in the proliferation stage whereas 6-(γ, γ-dimethylallylamine) purine (2-iP) promoted only single shoots. By increasing BAP concentration from 0.4 to 8 μM, inhibition of shoot growth was observed. By increasing the levels of indole-3 -butyric acid (IBA) and α-naphthaleneacetic acid (NAA) from 0.05 to 5 μM, a decrease of the proliferation rate of PR 204/84 at all BAP concentrations was observed. The highest shoot length was observed in the medium containing 4 μM BAP plus 5 μM IB A but it was not significantly different than 8 #GMM BAP plus 5μM NAA. Based on shoot proliferation, shoot length and overall appearance, the best media of the axillary shoot production study were those with 2 and 4 μM BAP and the absence of auxins in the medium. After 24 days in culture, excellent rooting of shoots (100%) was recorded on Murashige and Skoog (MS) media (full strength) containing 5 and 10 μM IB A and MS media (half strength) containing 2.5, 5, and 10 μM IBA. Mean length of roots was not significantly affected by IBA and mineral concentration of the culture media. From the results it was concluded that reducing mineral concentration of MS medium to half the normal value increased rooting percentage when IBA concentration was 2.5 μM, and mean root number when IBA concentration was 2.5 and 5 μM. The survival rate of plantlets surviving ex vitro in the greenhouse was 84%. © 2005 Taylor & Francis Group, LLC.