Breeding for the future
by Rasmus Madsen
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Climate change poses significant challenges to coffee production. Studies indicate that rising temperatures and shifting precipitation patterns are likely to hinder the growth, flowering, and fruiting of coffee plants. Additionally, these changes may escalate the prevalence of pests and diseases, ultimately diminishing both the quality and yield in various growing regions, underlining the importance of innovation within the sector. Breeding of new varieties has proven to be a potentially important tool in climate adaptation strategies.
Breeding Efforts
Breeding new varieties is a never ending process. Varieties bred for disease resistance, if we take leaf-rust as an example, will break the resistance over time, as new races of leaf-rust will develop, that the resistance genes in the plant will not ‘cover’. We have seen this happen for many newer varieties over time for various diseases. Over time, pests might find their way to work with the new varieties as hosts, which has been seen in other fruiting crops around the world. Inevitably, new pests will also invade and arise. If we count on breeding as a tool to mitigate climate change- and culture issues, we need to keep pushing and create new generations of selections continously.
The efforts in breeding new coffee varieties have been in progress over many decades. The earliest efforts in the 1950’s were focused on creating lines adapted to intensification (varieties with compact structures) and with a high cup quality. However, these lines proved susceptible to leaf rust, underlining the need for continous breeding efforts.
As coffee leaf rust became an increasing problem, later breeding efforts in the 1970-1980’s were focused on introducing the resistance genes of c.canephora into c.arabica. Natural crosses between c. arabica and c.canephora resulted in two groups of leaf rust resistant introgressed varieties - Sarchimor’s and Catimor’s, from which several diseases resistant varieties were introduced to the market. However, this time lacking cup quality. They were simply not designed to taste great as the industry was not demanding it at the time. In recent years we have seen the industry demanding higher quality coffees, which is why breeding efforts are now changing to emphasise a focus on quality as well.
But we learn from the past, and we are getting closer. The latest selection of first generation (F1) hybrid varieties have been developed with a primary aim of achieving high productivity and resistance across various climate conditions, while also focusing on fruit- and seed quality, which has seen a lot of modern varieties being superior in quality to traditional varieties. F1 hybrids were created by crossing wild African Arabicas (with good cup quality) and improved introgressed varieties (productive and resistant to coffee rust). Through hybridization, these varieties exhibit heterosis (hybrid vigour), showcasing superior traits compared to their parent plants. This enhanced vigour aids in maintaining or increasing yield amidst changing climatic conditions.
Field experiments have demonstrated that F1 hybrid varieties outperform traditional ones in terms of productivity (25-60% higher) and pest resistance across different agro-ecological zones. However, this comes with an increase in the usage of fertilisers and labour to live up to the promised benefits, which may be scarce in some regions, which could prove an obstacle in implementation.
Various crossbreeding initiatives involving private companies, national coffee organisations, and research institutions are underway globally. We have already seen the first of many modern hybrid selections, which have shown promise in experimental settings, but their performance in real-world commercial farming scenarios remains understudied. Are they as productive as promised? Are they really tolerant to pests and diseases over time? Some of these questions need answering, and evaluating a new variety for a fruiting crop, which has a lifespan over many years, takes time. Early days might seem promising for a lot of varieties, but devastating flaws might take time to discover (long-term vitality, long-term quality, biennial patterns, disease-resistance break-down, attractability to certain pests, etc.). These new hybrids have to be well-studied and evaluated before being introduced into the market as the rockstars of tomorrow. Otherwise, we might end up with an overwhelmingly large production area with varieties that do not deliver as promised, leaving coffee growers in the dark. Therefore, evaluating the performance of these new Arabica hybrids in commercial settings compared to traditional varieties in demonstration plots is essential for informing both farmers' decisions and policy-making processes.
Flora
One of the exciting new varieties which we have taken into consideration is a variety we have dubbed ‘Flora’. Flora is a first generation hybrid - an offspring between two widely genetically different number-varieties of c. Arabica used for breeding. It was bred for high productivity but with quality in mind when selecting parent-material. Initial tests are living up to our idea of a future-resilient variety with high productivity, immediate tolerance to the most important diseases, and a quality accepted by specialty coffee roasteries and consumers. For this reason, we have included it in a climate-controlled greenhouse trial to test its long-term properties and physiology, while we are also in the process of establishing a demonstration plot in Costa Rica and Colombia. We will investigate it for its adaptation to abiotic- and biotic stresses, tendency to be biennial in its bearing pattern, input-demands (water, fertiliser, labour), and fruit- and seed quality. With the application of new and innovative agricultural practices, we believe that we’ve come a long way to understand this new variety already - and the results are extremely promising.
Agronimic traits
Concerning the physical traits, we’ve observed that Flora has a good vitality. This vitality ensures a good establishment for the young trees, meaning we come into small productions already in the 2nd year from planting, and a full establishment in year 4-6. However, due to the high yields once established, it may come at the expense of coffee quality, while production of new fruiting wood can also be hindered, which may result in biennial bearing and overbearing-dieback. For this reason, we have implemented a technique called ‘thinning’, which Flora reacts very positively to. Thinning is a crop load management technique that has been practised in modern-day fruit production for many years, which involves removing excessive fruit from the trees to emphasise growth of new fruiting wood and to raise the quality of the remaining fruit. Effective crop load management is important for consistency in yield and ensuring a high fruit quality. While thinning isn't widely practised in coffee cultivation, we believe it holds promise for improving crop quality and yield stability for these new high-yielding varieties.
BBCH-identification keys for development stages of the coffee plant.
Percentage fruit retained at different stages of development as outlined in the BBCH-identification key.
Reaction to different percentages of fruit removal during the seed ripening stage (BBCH 75).
Flora also reacts quite well to pruning. Little is known about the impact of different pruning/training systems in coffee, which is something we are very focused on exploring. For other fruiting crops it is an integral part of the cultivation to lift productivity and quality. We have tried to train Flora to several different training systems (Spindle trees, 2-leader trees, hedge, and cordon-system) in different intensity (trees per. ha.) regimes, and it reacts very well to all of them with increased productivity and quality. With the pruning, we see that Flora always produces the best quality fruit on young wood, which requires a lot of renewal cuts to emphasise the growth of new wood, which is exactly what our pruning systems offer. We will keep exploring these techniques, while also keeping in mind creating a system with the lowest labour demand for pruning.
Quality traits
We’ve made a few interesting finds regarding quality with this variety as well. Flora seemingly thrives at high altitudes, where the formation of floral aroma compounds, such as terpenes, is accelerated (GC-MS verified). The result is a coffee bursting with floral aromas such as jasmine and orange blossom. To capitalise on this characteristic, it can be recommended to plant Flora in a place with stable cooler temperatures at higher altitudes. When subjected to medium altitude environments, the cup profile will, to a large extent, be dominated by esters, providing a fruit-forward profile.
Being very reactive to thinning due to its high vitality and productivity, a medium-light thinning will also dramatically increase the quality of the coffee providing it with a higher intensity, complexity and perceived sweetness as outlined in the table earlier.
Introducing Flora
In March 2024, we wanted to introduce this new variety and its traits to the world. We used a high-altitude-simulated cold washed process version of this coffee for the Danish Brewers Cup 2024, which won the 1st place. A coffee packed with floral aromas, fruit-forwardness and intense sweetness. We will bring this variety to the World Stage in Chicago in April 2024 to further promote how we can take a new high-yielding variety, and turn it into both an outstanding sensory experience and sustainable farming product by bridging the gap between research and practical application.
