Coffee production is a key player in Thailand's economy, generating an impressive annual revenue of over US$173.99 million. With Arabica and Robusta varieties being the most popular coffee choices worldwide, Thai Robusta coffee plantations dominate the south, constituting 75% of all Robusta coffee plantations.
On the other hand, Arabica coffee plants flourish in the northern regions of the country. To enhance coffee productivity and quality, the Thai government is adopting a coffee policy that prioritises increased production yields, aiming to boost competitiveness in ASEAN markets.
Fertiliser plays a crucial role in achieving better coffee productivity and quality. While chemical fertilisation has been effective in the short term, its long-term consequences on soil fertility have raised environmental concerns. As a result, sustainable agriculture practices are gaining momentum, especially for farmers with limited resources.
Nourish the plant, protect the soil
To address these challenges, researchers have turned their attention to the coffee rhizosphere, a zone surrounding the coffee plant's roots that is teeming with microorganisms. Some of these microorganisms, particularly bacteria and fungi, act as plant growth-promoting microbes or PGPM, positively influencing plant performance and growth.
Bacterial endophytes have garnered significant attention for their unique abilities to modulate plant growth and suppress plant pathogens without causing harm to the host plants. These microorganisms indirectly promote plant growth by producing beneficial phytohormones and enhancing nutrient availability in the rhizosphere. Consequently, PGPM has become an essential aspect of environmentally friendly agricultural systems.
Researchers have been exploring the potential of bio-fertilisers containing PGPM as a viable alternative to chemical fertilisers. However, a major hurdle in the advancement of this technology has been the limited shelf-life of these bio-fertilisers.
Shelf-life challenges
A recent study by researchers at Chiang Mai University delved into this challenge, evaluating four different carriers — perlite, vermiculite, diatomite and CCD — to prolong the shelf-life of two specific bacterial isolates, S2-4a1 and R2-3b1, over a span of 60 days after inoculation. The study also assessed the isolated bacteria's effectiveness as growth-promoting agents for coffee seedlings.
The researchers selected the two isolates based on their ability to solubilise phosphorus and potassium and produce indole-3-acetic acid (IAA), a growth hormone in plants. The isolates were then subjected to inoculation with the four different carriers and kept at an incubation temperature of 25 °C for 60 days. Throughout the experiment, the team closely monitored bacterial survival rates, pH levels, and electrical conductivity within each carrier.
Among the carriers tested, CCD emerged as a promising option. It exhibited a significant decline in both pH and electrical conductivity, setting it apart from the other carriers and reinforcing its potential as an excellent medium for sustaining bacterial population over time.
The researchers also tested the effectiveness of CCD-based bio-formulations of both the isolates on coffee seedlings. After applying the bio-formulations to the soil in pots containing Arabica plants, they observed that the coffee seedlings treated with the isolated bacteria-based bio-formulations showed enhanced growth and improved nutrient uptake. This suggests that the isolated bacteria possessed additional growth-promoting properties, making them valuable candidates for fostering sustainable agriculture practices.
The findings are a positive sign for Thailand's coffee industry as it aims for more environmentally friendly and sustainable agricultural practices. By harnessing the power of beneficial microorganisms and utilising CCD as a carrier, Thai coffee farmers could see increased crop productivity and overall quality, leading to a more competitive position in regional markets.
However, further research is necessary to identify optimal combinations of microorganisms that best support coffee seedling growth throughout their life cycle, ensuring long-term benefits for the industry. As Thailand embraces these innovative bio-fertiliser solutions, the potential for a greener, more sustainable coffee industry becomes increasingly tangible.
Source: National Library of Medicine
“Is coconut coir dust an efficient biofertilizer carrier for promoting coffee seedling growth and nutrient uptake?”
https://doi.org/10.7717/peerj.15530
Authors: Yupa Chromkaew, et al.