Results of Photobiological Studies on Growing Lettuce under Multispectral Radiation Sources

Introduction. When growing plantations through using vertical farm technology, an important factor for regulating energy processes is electromagnetic radiation of irradiators with certain optical wavelengths. Aim of the Article. The aim of the study was to substantiate the technology of application of LED radiation for growing green crops in vegetation facilities under conditions of multispectral radiation by determining the patterns of changes in the qualitative indicators of lettuce varieties Cook, Chrysolite and Afitsion and to create the concept of LED irradiators for controllable crop production. Materials and Methods. The experiment was conducted in the vegetation facility, in three chambers of which different radiation (in spectrum) of biological objects (green plants) was created using irradiators of different spectrum, other things being equal. Results. Experimental studies have determined a range of diverse reactions to radiation of a certain spectral composition. Stable increase in the content of threonine, phenylalanine, valine, serine, alanine and sugars was found in lettuce variety Cook grown under the irradiator with adjustable spectrum. At the same time, a stable decrease in the content of these substances was observed in lettuce variety Chrysolite grown under the irradiator with controlled spectrum. For vitamin C content, the reaction was the opposite: a decrease in vitamin C content in lettuce variety Cook and an increase in vitamin C content in lettuce variety Chrysolite grown in a spectrum-controlled irradiator. For lettuce variety Afitsion, the response to the content of the test substances was dissimilar in both experiments. Discussion and Conclusion. The development and application of LED irradiators with fine turning for controlled crop production should be based on photobiological studies, taking into account specific responses of plantation varieties. For these purposes, there is proposed a technical solution with a set of LEDs controlled by individual channels using digital technologies.