Effect of Lighting Type on the Nitrates Concentration, Selective Bioactive Compounds and Yield of Sweet Basil (Ocimum basilicum L.) in Hydroponic Production

The effect of lighting basil with LED DR/B LB (Light Emitting Diode deep red/blue low blue) lamps throughout the cultivation cycle or for only 7 days before harvest, after the period of using HPS (High Pressure Sodium) lamps, was studied in comparison with the use of HPS lamps only, at the same light intensity. Plants of two Genovese type basil cultivars, recommended for pot and hydroponic cultivation, were used for the experiment. Plant growth observations were made and herb and leaf yields, dry matter, nitrates, potassium, phosphorus, calcium, total sugars, total soluble solids, ascorbic acid, chlorophylls, and carotenoids were determined. Plants of both tested basil cultivars grown under LED lighting were characterized by a higher content of ascorbic acid, carotenoids, and sugars and a lower content of nitrates than those grown under HPS lights. In plants grown under LED lighting only, nitrate content was on average 31% lower than under HPS lamps. The use of LEDs for the last 7 days of cultivation resulted in a significant reduction in nitrate content in only one of the studied cultivars. Further research on the effect of lighting type on sweet basil yield and quality, depending on other factors, both genetic and environmental, is recommended.