Introducing the Power of Plant Growth Promoting Microorganisms in Soilless Systems: A Promising Alternative for Sustainable Agriculture

Abstract

Soilless systems, such as hydroponics and aquaponics, are gaining popularity as a sustainable alternative to traditional soil-based agriculture, aiming at maximizing plant productivity while minimizing resource use. Nonetheless, the absence of a soil matrix poses challenges that require precise management of nutrients, effective control of salinity stress, and proactive strategies to master disease management. Plant growth-promoting microorganisms (PGPM) have emerged as a promising solution to overcome these issues. Research demonstrated that Bacillus, Pseudomonas, and Azospirillum are the most extensively studied genera for their effectiveness as growth promoters, inducing changes in root architecture morphology. Furthermore, PGPM inoculation, either alone or in synergy, can reverse the effects of nutrient deficiency and salt stress. The genera Pseudomonas and Trichoderma were recognized for their solid antagonistic traits, which make them highly effective biocontrol agents in hydroponic systems. The latest findings indicate their ability to significantly reduce disease severity index (DSI) through mycoparasitism, antibiosis, and induced systemic resistance. In aquaponic systems, the inoculation with Bacillus subtilis and Azospirillum brasilense demonstrated increased dissolved oxygen, improving water quality parameters and benefiting plant and fish growth and metabolism. This review also establishes the interaction variability between PGPM and growing media, implying the specificity for determining inoculation strategies to maximize the productivity of soilless cultivation systems. These findings suggest that using PGPM in soil-free settings could significantly contribute to sustainable crop production, addressing the challenges of nutrient management, disease control, and salinity issues.

Optimization of Plant Nutrition in Aquaponics: The Impact of Trichoderma harzianum and Bacillus mojavensis on Lettuce and Basil Yield and Mineral Status

“…Although research on PGPMs in a soil-free environment currently lags behind that in soil, according to Barteleme et al [4], certain parallels among plant-microorganism interactions from a soil environment are preserved. This statement is supported by studies from Gravel et al [33], Cerozi and Fitzsimmons [34], and Sheridan et al [35] or review articles by Dhawi [36] or Mourouzidou et al [37].…”

Microbiological Biostimulants in the Improvement of Extended Storage Quality of In Vitro-Derived Plants of Popular Ornamental Perennials

“…BactoFungiStop and Guard, on the other hand, are designed to enhance disease resistance and mitigate stress. Therefore, the positive effects observed in the studied perennials may be linked to the plants' ability to develop proactive strategies to manage disease or cope with stress more effectively [30]. Microroganisms establish symbiotic relationships with plants, promoting nutrient exchange and triggering systemic responses.…”

Fertilization of Microbial Composts: A Technology for Improving Stress Resilience in Plants

“…Biofertilizers utilize beneficial microorganisms to optimize plant growth by increasing nutrient supply, effectively enhancing overall nutrient availability, and promoting healthier and more robust plant development [34,35]. Generally, the potential of different beneficial microbes, including nitrogen fixers, phosphorus solubilizers, potassium solubilizers, iron mobilizers, as well as the microbes capable of producing phytohormones, is utilized during biofertilizer synthesis which improves the nutrient profile of the soil [36,37]. Subsequently, the microbe-oriented nutrient recycling through biofertilizers enhances the soil organic matter content and maintains the soil health and sustainability, which is ultimately followed by healthy plant growth.…”