Abstract
Increasing environmental concerns and growing demand for safer and sustainable food production presents significant challenges for agricultural production. One potential technique, which could help improve crop productivity without adverse impact on the environment, is the use of beneficial microbes in crop production systems. This study evaluated the effects of three Azospirillum brasilense strains on tomato seedlings fertilized with effluent from freshwater fish aquaculture. Seeds were inoculated with A. brasilense strains Sp7, Sp7-S and Sp245 before sowing and after transplanting. Seedlings were raised under controlled greenhouse conditions with natural light. Inoculated seedlings produced longer roots (67%), bigger leaves (22%), higher seedling biomass (>33%), and greater protein (15%) and endogenous plant IAA (94%) contents. Inoculation with Sp7 and Sp245 increased the number of leaves and stem diameter by 8 and 10%, respectively. Seedling height was also increased by inoculation, but only with Sp7. In addition, seedlings inoculated with strains Sp7-S and Sp245 had higher total phosphorus content, while inoculation with Sp245 increased the activity of the enzyme peroxidase, which suggests that plant defense responses had been triggered. The result demonstrates the potential of the applied A. brasilense strains to enhance the usefulness of fish effluent as fertilizer for tomato seedling production.
Highlights
Recycling nutrients from organic sources and modifying farming practices towards sustainable agriculture have gained attention in recent years
This study evaluated the impact of Azospirillum brasilense inoculation on the performance of tomato seedling grown in soilless culture with fish effluent as fertilizer
Only data with significant results are presented in the succeeding table and figures
Summary
Recycling nutrients from organic sources and modifying farming practices towards sustainable agriculture have gained attention in recent years. Some studies reported that plants fertilized solely with fish wastewater, in a system called aquaponics, showed mineral deficiency symptoms, which could be due to either inadequate nutrient availability or inability to recover nutrients efficiently [3,4]. In this regard, the use of beneficial microbes has been considered one possible safe, efficient and practical agent to enhance plant growth [5]. One group of beneficial microbes is referred to as plant growth-promoting rhizobacteria (PGPR) They can act as biostimulants through phytohormone production, mineral solubilization, improving nutrient uptake efficiencies, and increasing tolerance to stresses [6]
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