Cultivar Variety and Added Potassium Influence the Nutraceutical and Antioxidant Content in Hydroponically Grown Basil (Ocimum basilicum L.)

The potential impact of increased levels of potassium (K+) in hydroponic solution on the production of bioactive compounds, which provide added value to products, is relevant for local economy and human health. This research pursues assessing different levels of K+ on the nutrition of basil, an important aromatic crop in the arid region of La Laguna, northern Mexico, where water scarcity demands the conversion from open-field agriculture to hydroponics. A randomized complete block design with a factorial arrangement (3 × 4) was used to determine the content of nutraceutical components, including polyphenolic compounds, flavonoids, anthocyanins, vitamin C, chlorophylls, and the antioxidant capacity of three varieties of hydroponic basil, with four doses of K+ in the nutrient solution, 7, 9, 11 and 13 mmol L−1. The analysis of variance showed significant differences (p ≤ 0.001) in most of the response variables, caused by the genotype and doses of K+. The antioxidant capacity of assessed cultivars was improved when doses of K+ were increased in the nutrient solution. Furthermore, the antioxidant capacity was positively correlated to the content of flavonoids (r = 0.621), anthocyanins (r = 0.655) and total phenolic compounds (r = 0.549). In conclusion, the nutraceutical content was increased in basil when controlling K+ in the nutrient solution.