Greenhouse Production of Basil: Effects of Hydroponic Systems and Cultivar Selection

Basil (Ocimum L. spp.) is the most popular fresh culinary herb. However, there is a lack of data characterizing the effect of hydroponic production systems and cultivars on the yield of hydroponically produced basil. Our objectives were to quantify productivity and characterize growth of basil cultivars grown in two different hydroponic production systems. Seeds of 35 basil cultivars, including selections of O. basilicum L. (sweet basil), O. tenuiflorum L. (holy basil), and O. ×citriodorum Vis. (lemon basil), were chosen. Seeds were sown into phenolic foam propagation cubes, placed in a growth chamber with a target air temperature of 24 ºC, and irrigated with deionized water or a nutrient solution. Two weeks after sowing, seedlings were transplanted into nutrient-film technique (NFT) or deep-flow technique (DFT) systems in a greenhouse with a mean temperature of 23.8 ºC. Nutrient solutions were maintained at a target pH of 6.0 and electrical conductivity of 1.6 mS∙cm−1. Three weeks after transplanting, fresh mass was recorded. Shoots were then placed in a forced air drier maintained at 67 °C for 3 d then weighed and dry mass was recorded. There was no interaction between basil cultivars and hydroponic production system. Fresh and dry mass of plants grown in DFT systems was 2.6 and 0.2 g greater, respectively, compared to plants grown in NFT systems. Basil cultivar differed greatly in fresh mass. Fresh mass varied among sweet basil cultivars, with the highest-producing cultivars ‘Italian Large Leaf’ and ‘Nufar’, yielding 50.6 g and 43.7 g, respectively; alternatively, fresh mass of ‘Emily’ was 15.0 g. Purple basil generally yielded less than sweet basil cultivars, with fresh mass ranging from 31.5 g (‘Aromatto’) to 4.2 g (‘Amethyst Improved’). Fresh mass of Thai basil [O. basilicum var. thyrisiflorum (L.) Benth.] and bush basil [O. basilicum var. minimum (L.) Alef.] was 19.4 g to 26.9 g, while holy basil was 50.6 g. Lemon cultivars varied in fresh mass, from 26.5 g (‘Lemon’) to 39.7 g (‘Lime’). The yield of basil seems to be affected more by the cultivar selection than hydroponic production system. Therefore, hydroponic basil producers should select basil cultivars based on flavor and yield, while hydroponic systems should be selected based on operational preferences.