Effects of Nutrient Solution Concentration and Daily Light Integral on Growth and Nutrient Concentration of Several Basil Species in Hydroponic Production

Our objective was to quantify the effect of mineral nutrient concentration of a nutrient solution on the growth of basil species and cultivars grown under high and low photosynthetic daily light integrals (DLIs). Sweet basil (Ocimum basilicum 'Nufar'), lemon basil (O. Xcitriodorum 'Lime'), and holy basil (O. tenuiflorum 'Holy') seedlings were transplanted into nutrient-film technique (NFT) systems with different nutrient solution electrical conductivities (EC; 0.5, 1.0, 2.0, 3.0, or 4.0 ds.m(-1)) in greenhouses with a low (approximate to 7 mol.m(-2).d(-1)) or high (approximate to 15 mol.m(-2).d(-1)) DLI. Although nutrient solution EC did not affect growth and morphology, increasing DLI did. For example, when sweet basil was grown under a high DLI, the fresh and dry weight, height, and node number increased by 144%, 178%, 20%, and 18%, respectively, compared with plants grown under the low DLI, and branching was also stimulated. In contrast, DLI had little effect on tissue nutrient concentration, although nutrient solution did. Most tissue nutrient concentrations increased with increasing EC, with the exception of Mg and Ca. For example, N in sweet basil increased by 0.6% to 0.7% whereas Mg decreased by 0.2% as EC increased from 0.5 to 4.0 dS.m(-1). Across treatments and basil species, tissue nutrient concentrations were generally within recommended ranges with no visible deficiencies. Based on our results, nutrient solution concentrations for hydroponic basil production can be selected based on factors such as other species grown in the same solution or by reducing fertilizer inputs.