Assessment of the biological products and led irradiation influence on thyme plants in closed agroecosystems

The aim of the study is to investigate the effect of biofertilizers based on adaptive PGPR bacteria on the rooting process of thyme cuttings and to evaluate the impact of LED irradiation on the quality indicators of common thyme biomass. The object of the study was common thyme (Thymus vulgaris L.), variety Krymrozovets, bred by the Federal State Budgetary Scientific Institution Research Institute of Agriculture of Crimea. The rooting ability of common thyme cuttings taken from mother plants was assessed using PGPR bacteria under controlled conditions of a closed agroecosystem. At the rooting stage using the Arthobacter mysorens monoculture, 76 % of cuttings took root on a peat substrate, which corresponded to the control variant (82 %); on a mineral wool substrate, an increase in the survival rate of cuttings by 1.8 times (65 %) was observed compared to the control (36 %). Treatment of thyme cuttings with a consortium of PGPR bacilli Bacillus sp. reduced survival on both peat and mineral wool substrates compared to the control. When studying the effect of LED irradiation on the qualitative indices of common thyme biomass, differences in the accumulation of essential oil and in the synthesis of amino acids were observed. The highest yield of essential oil (1.01 %) was recorded when treating with PAR of 230 mmol/m2s, the lowest (0.46 %) - when using PAR of 106 mmol/m2s. The total content of amino acids (arginine, lysine, phenylalanine, leucine + isoleucine, valine, proline, threonine and alanine) in the biomass of thyme grown under reduced irradiance (106 mmol/m2s) was 23.9 % higher than in plants grown under increased irradiance (230 mmol/m2s).Among all the analyzed amino acids, leucine + isoleucine (Leu + Ile) predominate with a total content from 901.1 (PAR - 230 mmol/m2s) to 1055.2 (PAR - 106 mmol/m2s) mg/100 g. To achieve optimal quality parameters of the obtained raw materials, it is recommended to grow plants under conditions of reduced LED irradiation at a PAR of 106 mmol/m2s of a closed agroecosystem.