Plant Growth Promoting Bacteria for Aquaponics as a New Strategy That Grants Quality and Nutrient Efficiency in Kohlrabi Cultivation

Abstract

Consumers are becoming increasingly concerned about eating healthy, and the products they consume are produced in an environmentally friendly way. Therefore, in this work, production techniques such as aquaculture and the use of plant growth-promoting bacteria in kohlrabi cultivation (Brassica oleracea L.) were studied. To this end, we applied three types of irrigation treatments (control, mixed water (50% fish effluent/50% drainage water) (mixed water), and mixed water enriched with synthetic fertilizers (mixed water + S)) combined with two formulations of plant growth-promoting bacteria (B1 and B2) in kohlrabi plants. Our data showed that the B1 inoculum combined with control irrigation caused both the increase in dry matter and the diameter of the bulb (17.8% and 8.9%, respectively); moreover, this inoculum increased the concentration of Ca when applied with mixed irrigation solution (water + S), and Zn for the B2 inoculum. The nitrogen utilization efficiency (NUtE) was augmented by the mixed irrigation treatment, with the lowest concentration of nitrates observed in the bulbs. Both inocula increased the total phenolic compounds in the control irrigation, whilst an increase in fructose and sucrose concentrations was only observed with B2.

Keywords

• red tilapia
• purple kohlrabi
• nitrates
• organic fertilization
• aquaponics system
• circular economy framework