By: Dr. Zakry Fitri bin Ab Aziz

Plant growth-promoting rhizobacteria (PGPR) have the potential to be a ray of hope in the agricultural sector, which is grappling with the conflict between food production demands and environmental sustainability. These little friends, who live in the soil zone that plants roots affect, the rhizosphere, provide a plethora of advantages that boost agricultural yields and encourage ecological resilience in the long run.

A Better Understanding of PGPR's Role

Plant growth-promoting rhizobacteria (PGPR) are a group of bacteria that are intimately associated with plant roots and can form symbiotic relationships with plants. In a mutualistic relationship, PGPR supply their plant hosts with carbon sources and a hospitable niche in the rhizosphere in return for vital nutrients and growth-stimulating chemicals.

Improved nutrient availability is a key mechanism by which PGPR benefit plants. Plants benefit from these microbes because of their capacity to mobilise and solubilize nutrients like micronutrients and phosphorus. In instance, plants generally have difficulty effectively absorbing phosphorus because of the forms it is typically found in soils. In order to improve plant growth and development, PGPR helps with phosphorus acquisition through processes including siderophore synthesis and phosphate solubilization.

In addition, PGPR are essential to agricultural environments' nitrogen cycle processes. Rhizobacteria have the ability to fix atmospheric nitrogen to ammonium ions, a process known as biological nitrogen fixation (BNF). Nitrogen fertilisers are an important part of conventional farming, but this capability can cut down on nitrogen losses to the environment, which means less pollution in water and less greenhouse gas emissions.

Auxins, cytokinins, and gibberellins are phytohormones that are produced by PGPR and have an effect on plant growth beyond nutrient acquisition. Hormones control many stages of plant life cycle, such as stem and root development, flowering, and fruiting. By increasing the efficiency with which plants absorb nutrients and stimulating root growth, PGPR help plants adapt to harsh environments that are harsh on their roots, such as those caused by drought, salt, and disease. In the midst of climate change, when unpredictable weather patterns threaten agricultural productivity, this resilience is becoming more and more valuable.

Promoting PGPR's Environmental Benefits

Biofertilizers and inoculants based on PGPR have a tremendous impact on soil health and environmental sustainability. A more stable and resilient soil ecology is fostered by PGPR, in contrast to synthetic fertilisers that can lead to soil degradation and nutrient imbalances in the long run. Soil aggregation and water retention are the results of beneficial bacteria's efforts to increase microbial diversity and improve soil structure, two factors that contribute significantly to soil fertility and erosion reduction.

Reduced chemical fertiliser use is another benefit of PGPR that helps keep the environment clean. Not only can synthetic fertilisers increase nitrogen runoff into aquatic bodies, which causes eutrophication and biodiversity loss, but they also add to greenhouse gas emissions during manufacture. Water quality and aquatic ecosystems are protected by PGPR-supported nutrient management methods, which lessen these hazards through increased efficiency in nutrient usage and less leaching of nutrients.

Social and Economic Consequences

Integrating PGPR into farming systems could help farmers save money, from an economic perspective. The development and application of biofertilizers may require early investments, but the long-term advantages, including increased crop yields, decreased input costs, and better soil health, usually justify these costs. In addition, farmers can reduce their exposure to production risks caused by climatic unpredictability and secure more consistent revenues and yields by utilising PGPR's resilience against environmental pressures.

More generally, PGPR is in line with international initiatives to encourage sustainable farming methods. Farmers can help reduce the impact of climate change, preserve natural resources, and improve food security by shifting their focus from synthetic inputs to biological solutions. There will be more trust and transparency in food systems as a result of these practices, which appeal to customers who are worried about the impact of agriculture on the environment.

Important Factors to Think About

There are a number of obstacles that prevent PGPR from being widely used, despite their many advantages. Research needs to be focused on specific soil types and crop species in order to find solutions that work consistently across all of them. Furthermore, in order to guarantee quality control and effectiveness in various agricultural contexts, it is necessary to establish infrastructure and obtain regulatory support in order to scale up manufacturing and distribution of products based on PGPR.

Facilitating adoption among farmers also relies heavily on raising awareness and providing education. In order to help agricultural communities fully utilise the potential of PGPR, outreach programmes and knowledge-sharing efforts are essential. To make the most of PGPR in sustainable agriculture, researchers, extension services, and stakeholders from the private sector must work together to close the gap between theoretical innovation and practical application.

Looking Ahead and Introducing New Ideas

Future plans call for more study into how to make PGPR-based technology more effective and scalable. Discovering new PGPR strains with improved beneficial features and comprehending how they interact with soil microbiomes are both made possible by recent advances in biotechnology, genetics, and microbial ecology. To further maximise the long-term benefits of PGPR in agricultural ecosystems, new formulation and delivery systems are being developed with the objective of optimising their application and persistence.

Ultimately, rhizobacteria that promote plant growth are an important part of sustainable agriculture since they can lead to more sustainable and long-lasting food production methods. Soil health, crop productivity, and environmental problems linked to conventional farming can all be improved by farmers utilising the inherent potential of these microbial companions. The incorporation of PGPR exemplifies the revolutionary potential of biological solutions in moulding the trajectory of agriculture as we face the dual challenges of meeting the food needs of an expanding global population and protecting the planet's limited resources.

About the writer:

Dr. Zakry Fitri bin Ab Aziz is a Senior Lecturer in Soil Microbiology and Biofertiliser at Universiti Putra Malaysia Bintulu Sarawak Campus, Sarawak, Malaysia. He is a life member and council member of the Asian PGPR Society for Sustainable Agriculture – Malaysian Chapter. His research focuses on biochar-based fertilizers with Plant Growth-Promoting Rhizobacteria (PGPR) to improve crop productivity and reduce chemical fertilizer use.

Pictures/Illustration (followed by caption):

Growth of plant growth-promoting rhizobacterium Bacillus thuringiensis on nutrient agar plate.

Enhanced and vigorous growth of black pepper vines with PGPR and half dose of NPK (left) compared to full dose of NPK fertilizer (middle) and half dose of NPK fertilizer alone (right).

Farmers can reduce production risks from climatic unpredictability and secure consistent yields and revenues by utilizing PGPR's resilience to environmental pressures.

Future plans involve further research into enhancing the effectiveness and scalability of PGPR-based technology. This includes the discovery of new PGPR strains with superior beneficial properties.

Date of Input: 18/07/2024 | Updated: 18/07/2024 | lanz