Spinach (Spinacia oleracea cv. Carmel) was grown in a conventional glass greenhouse under\nthree different nutrient solution treatments. Lighting and temperature conditions were identical. Six\ngrowing systems were used to provide a duplicate trough system for each of these three treatments.\nSix trials were harvested from each system over a two month time period. Two treatments received\nhydroponic nutrient inputs, with one treatment at pH 7.0 (referred to as H7) and the other at pH 5.8\n(H5), and the third treatment was aquaponic (A7), receiving all of its nutrients from a single fish\ntank with koi (Cyprinus carpio) except for chelated iron. System pH was regulated by adding K2CO3\nto aquaponic systems and KOH to hydroponic systems. Comparisons made between treatments\nwere total yield, leaf surface area, tissue elemental content, and dry weight to fresh weight ratio.\nDry weight biomass yield values were not different in pairwise comparisons between treatments\n(A7 vs. H5: p = 0.59 fresh weight, p = 0.42 dry weight). Similarly, surface area results were not\ndifferent between treatments. The important comparison was that A7 achieved the same growth as\nH5, the conventional pH with a complete inorganic nutrient solution, despite unbalanced and less\nthan ââ?¬Å?idealââ?¬Â nutrient concentrations in the A7 condition.
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