#103Symbiotic fungi
103⸱AConcept
- Improves plant nutrition
- Improves water uptake by the plant
- Improves the coffee plant’s tolerance to drought
- Improves the coffee plant’s tolerance to diseases
- Reduces coffee mortality
- Increases the coffee yield
Symbiotic fungi-plant interactions bring various benefits for the coffee plant, especially in view of climate change impacts such as drought and increased prevalence of diseases. They can be added to the soils of coffee tree seedlings in polybags or to new plantations. Seedlings whose soil has been inoculated with symbiotic fungi in the nursery stage were shown to grow more extensive root systems. They were, therefore, better prepared to withstand drought when transplanted to the field. Also, companion tree seedlings benefit from this kind of symbiosis.
Mycorrhizae (plural of mycorrhiza) are such symbiotic associations between fungi and plant roots. The mycorrhizal fungus colonizes the plant’s root tissues either only from the outside (ectophytic) or by entering the plant cells (endophytic). Both organisms benefit from this association: The plant produces organic molecules through photosynthesis and provides them to the fungus as sugars or lipids. In return, the fungus provides the plant with water and nutrients, especially phosphorus. This is because, compared to plants, mycorrhizal fungi have a much greater ability to release minerals and water from the soil. Mycorrhizae obviously also provide general protection against many pathogens, including root-knot nematodes, especially when the symbiosis is established early in the plant’s lifecycle.
Trichoderma is a genus of fungi that is present in all soils. Trichoderma species usually form endophytic symbiotic relationships with plant roots. They have the ability to promote root growth, obviously by secreting compounds that promote root branching. According to studies, they are able to inhibit the growth of phytopathogens due to their mycoparasitic capacity, through antibiosis, and because they compete with them for niches and nutrients.
Mycorrhizae and Trichoderma species both improve the coffee plant’s tolerance to biotic and abiotic stresses. They make nutrients and water available to the plant and additionally stimulate the growth of the plant roots, making them better able to reach water and nutrients in deeper soil layers. Therefore, the coffee plants grow better, and gain higher yields. Both types of symbiotic fungi act as biocontrol agents. Additionally, Trichoderma acts as a growth bio-promoter.
103⸱BTo be considered
The application of symbiotic fungi can be combined with Deeper polybags for even better survival rates of coffee seedlings after transplantation to the field.
There is evidence that coffee trees that have been planted in soil with mycorrhizal fungi need less fertilizer because more of their nutrition comes from microbial sources. Another factor associated with mycorrhizal fungi is the increase in the absorption area of the roots and, consequently, better use of the nutrients present in the soil.
Due to their function as biocontrol agents, symbiotic fungi can also reduce the need for chemical pesticides.
Mycorrhizae contribute to plant growth even if general soil condition is poor – i.e. low organic matter, high temperatures, and high aluminum – but best results are obtained under favorable conditions, and it is advisable to use them in conjunction with other adaptation tools, such as Mulching and Biochar, as part of a comprehensive soil rehabilitation effort.
Timing
It makes sense to inoculate the soil and plant roots with the fungi already in the nursery stage, before planting it to the field. This is because the cost increases progressively with every development stage.
103⸱CImplementation
Materials
Mycorrhizae powder (e.g.Vesicular Arbuscular Mycorizae, 8 spores/g of substrate).
and/or
Trichoderma (e.g. Trichoderma harzianum). In Brazil, there are several commercial products based on Trichoderma registered for the control of plant diseases, classified as biofungicides and bionematicides.).
There are products that combine mycorrhizae and Trichoderma to increase the plants' response to the bioproducts. Mycorrhizae have a slower colonization rate, while Trichoderma has a rapid expansion and high colonization capacity.
All are available with selected commercial providers.
103⸱1Application Mycorrhizae
Seedlings growing with Mycorrhizae
103⸱2Trichoderma
Seedlings inoculated with Trichoderma
103⸱DEconomic benefits
Lower fertilizer costs
This tool allows for a lower demand for synthetic fertilizers and therefore saves input costs over time.
Lower pesticide costs
This tool reduces the demand for pesticides and therefore saves input costs over time.
Lower renovation costs
This tool increases the lifespan of the coffee trees. They need to be renovated less frequently which reduces the long-term production costs.
Higher coffee yield
The effects of this tool can lead to a higher coffee yield and therefore a higher income.
103⸱EGreen benefits
Less synthetic fertilizers needed
This tool reduces the need for syntheticfertilizers. This reduces carbon emissions and water pollution, improves soil life, and saves resources.
Less pesticides needed
This tool reduces the need for pesticides. This reduces water pollution, protects the ecosystem, improves soil life, and saves resources.
Better soil life
This tool helps improve soil life (microbes, earthworms, etc.). This plays a vital role in plant nutrition and contributes to a healthy ecosystem.