The role of biofertilizer on the growing efficiency of Callisia fragrans cultivated under open-air hydroponic conditions of the Ararat Valley

Abstract

Background: Invention of biofertilizers (BFs) is considered to be one of the most important achievements of modern agriculture. Although these microbial bioproducts have not found widespread usage in soilless production, there is an increasing trend of research studies on BFs in hydroponics. Objective: In consideration of the high potential of biofertilizers (BFs) in hydroponics, this study examines the impact of BF on the growth efficiency of the medicinal plant Callisia fragrans (Lindl.) Woodson (C. fragrans) under open-air hydroponic conditions in the Ararat Valley for the first time. Methods: The plants were grown in a mixture of gravel and volcanic red slag. During the vegetation period, chemical fertilizer (CF), BF, as well as their different combinations were supplied to the plants. Plant’s growth and development regularities were studied via biometrical measurements, which were done periodically during the growing process. Physiological (chlorophyll a, b, carotenoids), bio- and pharmacochemical (extractive substances, total amount of flavonoids, anthocyanins) analyses were done in the medicinal raw material. The obtained data were subjected to the statistical evaluation. Results: At the end of the experimental period, the plants nourished with a combination of CF and BF, where the BF was supplied via foliar feeding (FF), as well as the plants given only CF through root application (RA), exhibited 2.9-3.5 times higher fresh overground biomass compared to the plants given BF (FF) alone. The application of BF (FF) with the combination in CF significantly increased the content of chlorophyll b and carotenoids in the leaves of plants compared to the BF (FF) variant. The maximum accumulation of anthocyanins and flavonoids of plants were mostly observed in the plants given the combination of CF and BF through the roots, as well as the ones given BF (FF) alone. Significant difference on the biosynthesis of extractive substances in the medicinal raw material between the variants has not been observed. Conclusion: Summarizing the preliminary results of the experiments, it is becoming obvious, that the application of BFs has great potential in hydroponics in order to enhance growing efficiency of C. fragrans. Keywords: C. fragrans, biofertilizer, chemical fertilizer, bioactive compounds, hydroponics, medicinal raw material