Optimisation of conditions for artificial lighting of ornamental plants at their adaptation after clonal micropropagation

The use of LED supplementary lighting for adaptation of cassette plants of heuchera and weigela after their clonal micropropagation compensates for insignificant natural illumination and low duration of photoperiod at the autumn-winter time. Supplementary lighting largely accelerates growth and accumulation of leaf biomass (leaf blade area, total area of plant leaves) as leaves are the primary photosynthetic organs. The formed leaf apparatus is the action place of assimilation processes, which determine the growth and development of other plant organs and affect the total plant mass. In the studied ornamental crops, the energy indicators of light sources (PAR, PPFD, illuminance level) directly affect the leaf blade area and the total leaf area indices (R=0.73...0.92). We have found positive correlations between the proportion of red range phytolamps in total spectrum with leaf mass (R=0.42…0.44) and total plant mass (R=0.42…0.56). Moreover, an increase in the proportion of blue spectral range is accompanied by a decrease in dry mass of the main plant organs and its total weight (R=–0.50…–0.78). The highest growth and development rates of heuchera and weigela plants are observed in Variants 4, 5 (full-spectrum LED phytolamps with high illuminance intensity) and 7 (a phytolamp with a red-blue spectrum and a violet tint of glow). Therefore, it is advisable to reduce the duration of their adaptation period by an average of 1.5 time. This, in turn, will allow for an increase in number of production cycles of horticultural seedlings per year using accelerated biotechnological methods – with a consistent combination of clonal micropropagation and plant adaptation in protected conditions (under glass) – to obtain plant material that meets high nursery standards.