EVALUATION OF BASIL Ocimum basilicum VARIETIES GROWN IN AN AQUAPONIC SYSTEM IN HUMBOLDT, CALIFORNIA
Basil (Ocimum basilicum) is the most frequently raised herb in aquaponics because it is a fast growing, good yielding crop with high cash-value. Comparative growth studies of basil varieties in the western United States are lacking. These comparisons are useful to aid aquaponic producers' decision-making to maximize profitability. The objective of this experiment was to compare production of eight basil varieties (dark opal, holy, Italian large leaf, lemon, lime, spicy globe, sweet Genovese, and Thai) in a modified Nelson and Pade, Inc. (Commercial 200) aquaponic system in a greenhouse facility on the Humboldt coast.
The aquaponic system consisted of four 1 m3 fish tanks, each containing approximately 26 white sturgeon (Acipenser transmontanus) that averaged 1,608 ± 508 g (mean ± SD), with a total feed input of 1,440 g/day, equal to 60.5 g of feed/day/m2 of plant growing area. Effluent from the fish tanks flowed through two AST Endurance™ bead filters and into one degassing tank, and then into two 11.8 m2 hydroponic beds. The flow rate through the hydroponic beds was 1,420 L/hour with an average retention time of 1.4 hours. Seedlings were planted at a density of 25 plants/m2 in replicated floating rafts. All plants were harvested and weighed two times by the "cut and come again" method. Yields (in kg/ m2) were analyzed using a two-way ANOVA to determine differences among varieties and harvest (using a significance level of P < 0.05).
Basil yield was significantly different among varieties (P<0.001), but not between the first and second harvest (P=0.627). Post-hoc pairwise Tukey comparisons indicated that yields of holy were significantly greater than all other basil varieties, by an average of at least 2.8-6.0 kg/m2 (Figure 1). Lime yield was the second largest and significantly greater than spicy, dark opal, and Italian varieties.
This experiment suggests holy basil is well suited for maximizing basil yields on the North Coast of California in an aquaponic greenhouse setting. We are in the process of conducting a second trial of our experiment.