Influence of fitohormones in the nutrient medium on the proliferation at the microplants of blue honeysuckle cultivars (Lonicera caerulea L. var. kamtschatica)

Abstract

The proliferation activity of blue honeysuckle microplants of cultivars ‘Krupnoplodnaya’, ‘Goluboye vereteno’, ‘Pavlovskaya’, ‘Volkhova’ at micropropagation stage is determined by hormonal composition of nutrient medium and genotype. An increase in concentration of 6-BA in MS medium from 0.2 to 1.5–2.0 mg/l leads to an increase in micropropagation rate from 1.91 to 3.26–3.57. The maximum micropropagation rate for cultivars ‘Krupnoplodnaya’ (3.43–3.47) and ‘Goluboye vereteno’ (4.11–4.23) was given at MS medium with addition of 1.5 and 2.0 mg/l 6-BA, for cultivars ‘Pavlovskaya’ and ‘Volkhova’ (2.80 and 3.90 respectively) – at medium with addition of 1.5 mg/l 6-BA. It is possible to increase micropropagation rate due to the joint use of two growth regulators: 6-BA (1.5–2 mg/l) and GA3 (1.0 mg/l). The use of gibberellic acid leads to formation of axillary branch, intensification of growth by increasing the length of internodes of shoots, which makes it possible to further divide long microshoots into microcuttings with two to three nodes.

It was found that use of TDZ actively stimulates proliferation of blue honeysuckle shoots and allows to obtain a high micropropagation rate (up to 12) at lower concentrations (0.3–0.6 mg/l) than use of 6-BA in high concentration – 1.5 and 2.0 mg/l (micropropagation rate was 2.80–4.23 depending on cultivar). However, TDZ inhibits growth of microshoots in length, forming a conglomerate, which is an accumulation of small shoots that are not suitable for rhyzogenesis stage, and therefore their subsequent elongation on a hormone-free medium is necessary. The use of TDZ in two consecutive subcultures for cultivating of blue honeysuckle is not desirable, as it leads even more to formation of small shoots.