Robusta: Not so Robust !? A New Research
Coffee is in crisis, due to climate change.
We in the industry all know this.
Companies like Karmic Circle Coffee Trading got into the coffee business to address this reality. In part by focusing on maximizing the quality of the Robusta plant (Canephora) due to its heat tolerant nature as compared to Arabica.
But before proclaiming Robusta as the savior species of the coffee industry, we must come to quantitative terms with exactly how ‘robust’ Canephora really is, if we are to accurately forecast the need for novel adaptive measures, including the genetic search for more resistant sub-variants.
Common wisdom by the Numbers:
In 2016 and 2017 researchers Garavito, Montagno, Guyot, Bertrand, Jayakumar, Rajavel, Surendran, Gopinath, and Ramamoorthy; as well as Laderach and colleagues claimed that “as temperatures rise, farmers could switch to Robusta to help maintain production” (as cited in Jath, et al., p.3678). However, Jath and the research team (2020) didn’t believe this alone could make up for the shortfall in profits, hence this longitudinal experiment was introduced to prove to what degree Robusta can stave off economic disaster in a changing climate.
Claims in the contemporary literature indicating that Robusta produced the highest yield in the temperature between 22 C and 30C, were unable to be replicated by Jath and team and appeared to use other indicators of plant vigor as a hasty proxy for fruiting productivity.
Jath, et al., (2020) explain that most research focuses on heat sensitivity and Arabica, and so much of Robusta research is scattered across decades and left unattended by the peer review community. This is because Robusta’s low maintenance nature was seen as its primary value, not quality optimization through painstaking horticultural optimization. And the more sensitive Arabica, as the first species to begin showing declines due to heat stress, has thus taken up most of researchers’ time. As opposed to looking down the road at the viability of coffee in a world in which Arabica no longer comprises the majority of coffee consumed.
As it turned out, the bulk of research on Robusta per Jath’s team’s findings, failed to directly investigate the relationship between yield and temperature. Hence, they sought out to create a pioneering study to put numbers to this dichotomy.
This longitudinal research took place in Vietnam and Indonesia from 2008 to 2017 and these countries account for 55% of the world’s Robusta production. According to Jath, et al., (2020), there were a total of 798 farms participating which consisted of 558 farms in Vietnam and 240 farms in Indonesia. This led to a large-scale study that analyzed farm-level Robusta coffee yield responses to temperature. 7000 coffee producers from both countries participated.
Key findings: Optimal growing season, average temp for Ro will be 20.5C
The belief that Robusta generally is heat tolerant and can thrive in the temperature zone between 22C and 30C, is true for the vegetal aspects of the plant. But these high temperatures do inhibit cherry yield. The current research comes out with a clear analysis on the relationship between these two variables.
|Criteria||Temperature (min)||Temperature (max)||Results||Yield Loss|
|Growing||lower or equal 16.2 C||24.1C||Optimal||0-5%|
|16.2 -18.6C||24.1 – 26.5C||Suboptimal||5-25%|
|18.6 – 20.7||26.5 – 29.5||Poor||25% – 50%|
|greater than 20.7C||greater than 29.5C||Very Poor||50%|
|Flowering||21.7 – 23.4C||lower or equal 25C||Optimal||0-5%|
|15.8 – 21.7C||25 – 29C||Suboptimal||5-25%|
|13.8 – 15.8C||29 – 32.9C||Poor||25% – 50%|
- Robusta is highly vulnerable to temperature and perhaps more similar to temperature sensitive arabica than previously thought.
- Robusta yields declined as mean minimum temperature rose above 16.2C
- During flowering, high mean minimums coupled with dry conditions were the most favorable for Robusta.
- Robusta with different genotypes might show a greater or lesser sensitivity to temperature.
- For every 1C increase from a mean minimum temperature of 16.2C, the yield will fall between 350 kg to 460 kg per hectare
Kath, J., Byrareddy, V. M., Craparo, A., Nguyen‐Huy, T., Mushtaq, S., Cao, L., & Bossolasco, L. (2020). Not so robust: Robusta coffee production is highly sensitive to temperature. Global change biology, 26(6), 3677-3688.