The effects of boron and NaCl induced salinity on growth and mineral composition of the pear (Pyrus communis L.) rootstock OH × F 333 shoots cultured in vitro were investigated. Shoots were grown in vitro for seven weeks on a Murashige and Skoog medium containing two B concentrations (0.1 and 2 mM) combined with five NaCl concentrations (0, 10, 20, 40, and 80 mM). Τhe longest shoots were produced at 0.1 mM B and 80 mM NaCl, but highest number of shoots were produced at 0.1 mM B and 0 -20 mM NaCl. Inclusion of 20 and 40 mM NaCl in the culture medium significantly increased fresh mass of cultures compared to 0 mM NaCl for all B concentrations tested. The concentrations of P, K, Ca, Mg, Na, Fe, Mn and Zn of plants were affected by B and NaCl concentration of the medium.
PR 204/84 rootstock (peach x 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 µM 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%.
The in vitro cultures of the PR 204/84 peach rootstock (Prunus persica P. amygdalus) produced the higher rooting percentage, mean root number, mean root length, fresh, and dry mass of roots when grown on media containing 88 mM sucrose or 88 mM glucose. Parafilm, rubber and aluminum foil as sealing materials were not significantly different in terms of rooting percentage, fresh, and dry mass of roots after 24 d in culture. he use of cotton as sealing material induced lower root number per shoot, length of roots, fresh, and dry mass of roots than the rest treatments.
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