Overview of Multiple Applications of Basil Species and Cultivars and the Effects of Production Environmental Parameters on Yields and Secondary Metabolites in Hydroponic Systems

Basil ( Ocimum basilicum L.), including other species and cultivars, is an excellent source of nutritional compounds, the accumulation of which can be stimulated by exogenous factors (environmental and nutritional conditions). Although best practices are relatively established for mature basil plants, microgreens production requires further research to optimize quality and quantity. The study objectives are (i) to provide an overview of the many uses of basil, (ii) collate and present common hydroponic systems available in the market, (iii) review effects of key production environment parameters on basil yields in hydroponic systems, and (iv) summarize the effects of the growth environments on yield quantity and quality of basil microgreens. The paper analyzes in detail key production parameters of basil microgreens in hydroponic systems, such as temperature, humidity, pH, electrical conductivity, dissolved oxygen, carbon dioxide, nutrient solutions, and the influence of light (quantity, quality, and photoperiods). The collated literature review has shown that basil, grown hydroponically, can tolerate high variations of environmental parameters: pH 5.1–8.5, temperature 15–24 °C, relative humidity 60–70%, electrical conductivity up to 1.2 mS cm −1 , depending on the developmental stage, dissolved oxygen at 4 mg L −1 (optimally 6.5 mg L −1 ), and light intensity between 200 and 400 μmol m −2 s −1 . The study has synthesized an overview of different production parameters to provide guidance on the optimization of environmental conditions to ensure the quantity and quality production of basil microgreens. Improving the quality of basil microgreens can ideally spur continued gastronomic interest in microgreens in general, which will encourage more entrepreneurs to grow basil and other microgreens. Hence, the study findings are a great resource to learn about the effects of different environments on basil microgreen production. This information can inform research for successful production of different species and cultivars of basil microgreens, and establishing testing protocols to improve the quantity and quality of the harvest.