Published 2020-10-19
Abstract
This study investigated whether the addition of Lactobacillus casei to a hydroponic system would increase the yield of arugula (Eruca vesicaria ssp. sativa) when compared to the control. Arugula was grown using an ebb and flood system with 0, 7, 14, or 21 oz of EM-1 (L. casei) added to the recirculating nutrient solution. Shoot and root growth, nutrient levels in the hydroponic solution and the leaves, and colony-forming units in solution and on the roots were measured. The addition of L. casei did not improve yield, and plant growth was similar among treatments. There was also no difference in nutrient levels in the hydroponic solution among the treatments, suggesting that L. casei did not improve nutrient uptake. This finding was supported by minimal differences in tissue nutrient levels. The number of CFU’s in the nutrient solution decreased each week from levels measured at the beginning of the week. The lowest number of CFUs in solution were for control plants. The CFU recorded on roots was greatest on plants grown with the 21-oz treatment. It appears that L. casei was living on the roots and in the solution. Improved growth with the addition of microbes is often observed when plants are exposed to abiotic or biotic stress. However, when plants are grown under optimum conditions, the benefits of adding microbes are often undetectable.