Improvement of the clonal micro-propagation technology elements for raspberries of various fruiting types

Abstract

The results of research on clonal micropropagation of 17 raspberry varieties of the Altai and European selection are presented. Recently, researchers have been focusing on creating a universal nutrient medium that would be equally suitable for any variety of a particular plant species. This is especially important for mass clonal micropropagation in production nurseries. The regeneration potential of the raspberry varieties of different types of fruiting at each stage of reproduction has been assessed. At the stage of actual micropropagation, it was found that Driver and Kuniyuki medium in our modification was superior to the Murashige and Skoog medium in terms of the shoot length and averaged 9.0 mm for common type varieties and 12.3 mm for remontant varieties. This made it possible to eliminate the additional stage of elongation of the microshoots. Also, the appearance of microshoots improved on the new medium. It was found that for raspberry, regardless of its type, the optimal concentrations of the growth regulators lie in the following range: cytokinin 6-benzylaminopurine (BAP) 2.5–3.5 μM together with auxin ß-indolyl butyric acid (IBA) 0.5–0.7 μM. At the stage of rhizogenesis, the best results were shown by the Driver and Kuniyuki medium with 2-fold reduced content of all main components and with the addition of 2.0 μM IBA at the passage duration of 21 days. After that, all microcuttings with and without roots underwent the adaptation stage – growth completion in neutral substrates for 56 days under ex vitro conditions in a vegetation room. In most cases, there were no statistically significant differences in the length and number of leaves regardless of the presence or absence of roots at the initial stage of adaptation. By the end of this stage, 100% of the adapted raspberry plants of the usual type of fruiting and 98% of the remontant type were obtained.