Coffee cultivation faces various challenges, including climate change, pests, diseases, and soil degradation. To combat these issues, horticulturists are turning to grafting, a technique that combines the strengths of different Coffea species. This article explores the grafting of Coffea Eugenioides onto Coffea Excelsa rootstock, a promising approach to improve coffee plants’ drought tolerance and overall resilience.
Coffea Excelsa stands out with its deep and robust root system, boasting a higher root-to-shoot ratio than Arabica and Robusta. This characteristic allows Excelsa to access water and nutrients from deeper in the soil, making it more drought-resistant and resilient against pests and diseases. Both Coffea Eugenioides and Coffea Excelsa being diploid (2n=22) species further make them compatible for successful grafting.
The decision to graft Eugenioides onto Excelsa is driven by Eugenioides’ relatively higher drought tolerance compared to Arabica and Robusta. The Excelsa rootstock is expected to bolster Eugenioides’ ability to withstand challenging environmental conditions. Additionally, this grafting project aims to collect valuable data, as more than 120 Coffea species remain relatively unexplored in comparison to extensively researched Arabica and Robusta.
The Grafting Process: Grafting is a straightforward technique that unites two plant parts, the rootstock and the scion. First, healthy rootstock and scion materials are carefully selected. The rootstock should be slightly taller than the scion. Next, both the rootstock and scion are cut at a 45-degree angle and then joined together, ensuring the cut surfaces align. Grafting tape or rubber bands hold them together, and the graft union is protected with grafting wax or paint to shield it from the elements.
The grafted plant is placed in a warm, humid environment, maintaining moisture without over-saturation. Grafting success depends on factors like the health of the materials, the grafter’s skill, and environmental conditions. Generally, coffee grafting enjoys a high success rate. In the case of Coffea Eugenioides on Coffea Excelsa, the success rate is notably high due to their close relation and similar growth habits.
By mixing and matching rootstock and scion, coffee growers can create plants that are not only more drought-tolerant but also resistant to diseases and more productive, offering a potential solution to the challenges posed by climate change in the coffee industry.
A Fascinating Discovery: An interesting side note reveals that India has its own variety of Eugenioides, known as SLN11, a tetraploid hybrid of Eugenioides and possibly Liberica, aptly dubbed “Ligenioides.” This coffee variety is small in bean size and exhibits excellent qualities as a low-intervention, pest, disease, and drought-resistant coffee. The image included in the article showcases a SLN11 sapling grafted onto an Excelsa rootstock, highlighting the potential of this unique graft.
- A.P. Davis, C. Kiwuka, A. Faruk, J. Mulumba, J. Kalema (2023) A review of the indigenous coffee resources of Uganda and their potential for coffee sector sustainability and development
- R. Meyers, A. Kawabata, A. Cho, S.T. Nakamoto (2020) “Grafted Coffee Increases Yield and Survivability”
- M. Mishra, A. Slater Recent Advances in the Genetic Transformation of Coffee
- Ligenioides: Coffee Selection 11, Santa Ram Link