Micro Propagation of Penta Rootstock (Prunus domestica) in the Two Culture Media (MS and B5)

Culture medium and growth regulators type can influence the growth traits and for determining the most effective medium and hormone compositions an extensive studies are needed; otherwise the culture medium may have a negative effect on the growth traits. In this research the effects of two culture media (B5 and MS) supplemented with two growth regulators (IBA and BAP) with different concentrations (0.5, 0.9, and 1.5 for IBA and 0.4, 0.8, and 1.2 mg/l for BAP) alone or in combination was evaluated. Studied traits were number of leaf per shoot, shoot length, number of regenerated shoots based on completely random plan with 5 replications.

Explants provided in the beginning of spring from mother plants growing in open environment. Shoot tips and axillary buds (0.3-0.4 cm long) used as the explants. After washing with tap water, explants were immersed in ethylic alcohol for few seconds (3-4 seconds) then immersed in mercuric chloride (0.005 W/V) for 5 minutes which supplemented with few drops of tween 20 and finally washed three times with sterile distilled water. Disinfected explants cultured on medium under air laminar flow bench. Growth chamber was adjusted to 16 hours light and 25 to 27ᵒC.

The results of variance analysis demonstrated significant differences between media, hormone level and interaction between hormone concentrations for traits studied. The results showed the longest shoot (6.39 cm) and the highest shoot number (13.65) obtained in MS medium supplemented with 0.8 and 0.4 mg/l BAP respectively. In this experiment the highest root number (8.41) and root length (14.75 cm) was observed in B5 and MS medium containing 0.9 and 1.5 mg/l, IBA.

Overall the most shoot proliferation of this rootstock occurred in MS medium. New shoots in MS medium showed normal and better growth comparing to shoots obtained in B5 medium, that can be one of the results of higher amount of nitrogen (ammonium nitrite) in MS medium. In B5 medium with all hormone treatments weak growth observed for this plant. In fact this medium was made for herbaceous plants and this is one of the main reasons why penta rootstock did not showed good growth symptoms on this medium.