2019 ASHS Annual Conference

Hydroponic culture of plants is a multi-billion dollar industry that permits year-round production of crops. The components of many commercial nutrient solutions are unlisted, making it difficult to anticipate effectiveness. In contrast, the recipe for Hoagland solution, a standard fertilizer solution for research in hydroponics, provides a wide variety of plants with all required nutrients. In the first of two experiments, we evaluated ‘Mrs. Burns’ Lemon’ basil (Ocimum basilicum var. citriodora) grown in deep water culture with one of three commercially available nutrient solutions [Advanced Nutrients pH Perfect Grow-Micro-Bloom (Advanced Nutrients), General Hydroponics Flora Series (Flora), or Remo Nutrients (Remo)] or half-strength Hoagland solution. Solutions were prepared to a concentration of 113 mg•L-1 nitrogen, while the concentration of other macronutrients and micronutrients varied. In the second experiment, we evaluated the effectiveness of mycorrhizal inoculants on basil growth. Although research supporting the colonization and effectiveness of mycorrhizal inoculants in hydroponics is scarce, mycorrhizae are sold for hydroponic production with claims of increased plant uptake of water, nitrogen, and phosphorous. To test colonization of endomycorrhizae and ectomycorrhizae, plants were cultured in either Remo or half-strength Hoagland solution with or without the addition of Root Magic Mycorrhizae (Blue Planet Nutrients) at the recommended rate of 0.27 g•L-1. In experiment 1, plants reached marketable size in five weeks, at which time SPAD was highest among plants in Advanced Nutrients and Flora and lowest among plants in Hoagland solution. Plants grown in Advanced Nutrients and Remo had the greatest heights, widths, and root and shoot dry weights, while plants grown in Hoagland solution were the smallest. In experiment 2, plant height did not differ between fertilizer treatments. However, plants fertilized with Remo had widths that were 40% greater and SPAD measurements that were 16% greater. Addition of mycorrhizae did not impact measures of growth in either nutrient solution. We conclude that fertilizer solutions differ in their effectiveness, and that inoculation with mycorrhizae is not beneficial for production of ‘Mrs. Burns’ Lemon’ basil.