Basil Performance Evaluation in Aquaponics

Basil (Ocimum sp.) is a fast-growing, high-value cash crop for aquaponics. Plant suitability evaluation in tropical conditions is critical to recommend new cultivars, increasing grower portfolio and minimizing the production risks associated with untested selections. Two trials were conducted to identify suitable basil cultivars for tropical outdoor aquaponics production using the University of the Virgin Islands (UVI) Commercial Aquaponics System in the U.S. Virgin islands. We evaluated five basil cultivars in Summer 2015 (Genovese, Lemon, Purple Ruffles, Red Rubin, and Spicy Globe), and seven cultivars in Fall 2015 (Cinnamon, Genovese, Lemon, Purple Ruffles, Red Rubin, Spicy Globe, and Thai). In both trials, 3-week-old seedlings were transplanted in net pots at a density of 1.5 plants/ft² (16.15 plants/m²). The 6-inch portions and upper portions of the canopy were harvested as a salable product and the resultant material (leaves and stems) considered as total yield per square meter. In the summer, yield was higher in ‘Genovese’ (14.91 kg·m⁻²) and ‘Spicy Globe’ (13.99 kg·m⁻²); ‘Purple Ruffles’ resulted in the lowest yield (4.18 kg·m⁻²). Leaf anthocyanin was greater for the red cultivars Red Rubin [28.35 anthocyanin content index (ACI)] and Purple Ruffles (34.36 ACI) compared with the other cultivars. Chlorophyll content was the highest in ‘Genovese’ [48.59 chlorophyll content index (CCI)]. In the fall, ‘Cinnamon’ (6.60 kg·m⁻²), ‘Genovese’ (6.70 kg·m⁻²), and ‘Spicy Globe’ (6.35 kg·m⁻²) showed the highest yield and ‘Purple Ruffles’ the lowest (1.68 kg·m⁻²). Leaf anthocyanin differed in all cultivars, with the higher values in Purple Ruffles (80.5 ACI) and Red Rubin (36.5 ACI). Chlorophyll content was a response of plant growth and cultivar, with values increasing over time and ranging from 12.06 (Lemon) to 17.99 CCI (Cinnamon). Plant growth index (PGI) was higher than that of other cultivars in Genovese and Lemon on day 58 (summer), and higher in Cinnamon on day 87 (fall). Yield was greater during the summer, which was calculated from May to August, in comparison with the fall, calculated from September to November. Yield declined for the fourth harvest in the summer, indicating that growers may need to end production after the third harvest and replant the crop. The results of this experiment indicate that basil has potential as a specialty, short-season, and high-value crop in the UVI Commercial Aquaponics System. Of the cultivars tested, Genovese and Spicy Globe were the highest yielding cultivars within the environmental and geographical conditions of this study for two consecutive seasons (summer and fall).