Influence of limiting factors on the development of Melissa officinalis L. plants during in vitro micropropagation and ex vitro adaptation

Melissa officinalis L. is a perennial herbaceous essential oil, medicinal and spicy-aromatic plant, widely used in medicine, as well as in the perfume and cosmetics, liquor and food industries. The low content of essential oil in lemon balm raw materials determines the need for breeding work aimed at creating high-oil cultivars. The use of in vitro biotechnological methods will increase the efficiency of this process and quickly multiply promising breeding samples. The aim of this work was to study the effect of cultivar on the development of M. officinalis plants during in vitro clonal micropropagation and ex vitro adaptation. It was found that at the stage of actual micropropagation, the optimal culture medium for the Sobornaya and Krymchanka cultivars was the one with the addition of 0,5 mg/l BAP (the multiplication indexes were 19,9 and 17,6, respectively), and for the Citronella variety, the optimal medium was the one with the addition of 1,0 mg/l kinetin (the multiplication index was 19,3). At the stage of in vitro rooting, the highest frequency of rhizogenesis for the Citronella and Sobornaya cultivars (75,5% and 93,3%, respectively) was on the culture medium with the addition of 0,5 mg/l NAA, and for the Krymchanka cultivar (90,9%), on the medium with 1,0 mg/l IAA. On these media, the studied cultivars demonstrated good development of the main and adventitious roots. The maximum survival rate of micro plants of three lemon balm cultivars during ex vitro adaptation (up to 93,3%) was provided by a substrate consisting of a mixture of peat, sand and perlite (2:1:2). The conducted studies were used to develop a protocol for clonal micropropagation of M. officinalis.