Influence of Bio-fertilizers on Growth, Yield and Anthocyanin Content of Hibiscus sabdariffa L. Plant under Taif Region Conditions

Abstract

The production of chemical-free medicinal and aromatic plants has been the focus ofinterest of many researchers and producers in order to ensure the high quality and safety, not only for human, but also for the environment. Therefore, the aim of this study was to investigate the effect of some bio-fertilization treatments on the growth, yield and sepal quality attributes of Hibiscus sabdariffa L. plant under Taif region conditions. The bacterial strains were isolated from the rhizosphere of plant roots grown in the study area and multiplied on media before treatment application. The bio-fertilizers applied in this experiment were Azotobacter chroococcum + Azospirillum brasilense as nitrogen fixing bacteria (NFB), Bacillus megatherium var. phosphaticum + Bacillus polymyxa as phosphate solubilizing bacteria (PSB) and the mixture between them as a combination treatment. Control plants were not treated with any bio-fertilizers. The results of this study showed that vegetative growth parameters, fruit number per plant and sepal yield were significantly increased due to NFB and/or PSB treatments applied relative to the control. The sepal quality attributes i.e. anthocyanin content and total soluble solids of inoculated plants were significantly enhanced in roselle juice compared with un-inoculated control however the pH value was reduced due to bio-fertilizer treatments. Moreover, the total chlorophyll, carbohydrates contents and macro elements of roselle leaves was significantly improved due to bio-fertilizer treatments relative to the control. Applying NFB and/or PSB treatment significantly reduced the nitrate and nitrite contents in roselle leaves relative to un-inoculated control. CO2 evolution in the soil of roselle plants treated with NFB or PSB was significantly higher than untreated plants at any time point during the growth. The combined treatment of NFB + PSB was superior to solely application concerning all investigated parameters.