Effect of zoohumus on the productivity and fatty acid profile of peppermint (<i>Mentha piperita</i> L.)

Abstract

Organic farming development involves minimizing or completely abandoning the use of mineral fertilizers in favor of organic ones. Regarding the cultivation of medicinal and aromatic crops, in the Pharmacopoeia this thesis is specified by the fact that using minimum synthetic substances, the obtained medicinal raw materials (MRM) will be environmentally friendly, without residual impurities of pesticides and heavy metals. The development of the organic farming industry entails the appearance of more and more new products on the market. One such source of secondary raw materials is black soldier fly (Hermetia illucens) zoohumus. The article aims to show the feasibility of using its alkaline extracts in cutting propagation of peppermint (Mentha piperita L.) in protected ground conditions. Plants were grown for 60 days in pot culture on a neutralized peat growing medium. The liquid zoohumus supplement was applied to the soil once by drenching the growing medium with concentrations of 0.2, 1.0, and 2.2 % of the working solution. The control was the variant of growing plants on water. At the end of the experiment, biometric and biochemical evaluations of the resulting green yield were made. The fatty acid profile of leaf extracts was analyzed by GC-MS. The study showed that M. piperita L. has a low yield of saturated fatty acids and a high percentage of unsaturated fatty acid synthesis. The dominant components among the latter were C18:3 (omega-ω3) and C18:2 (omega-ω6). Calculation of their ratio index showed an increase in the values in the zoohumus variants. In addition to nutritional value improvement, an increase in this parameter may mean an increase in membrane fluidity, which enhances the effect of cross-adaptation to multiple stresses in plants. At the same time, in comparison with the controls, the plants grown on a medium with zoohumus application turn out to be shorter, but bushier in terms of the shoot height to mass ratio. Having compared the obtained values for other nutritional indices, we concluded that the optimal concentration of the working solution for zoohumus application on a solid growing medium equals 1.0 %.