With a new decade of challenges and opportunities ahead in the potato sector, the 30th Cambridge University Potato Growers Research Association (CUPGRA) conference at Robinson College focused on building business resilience.
By using combinations of existing sprout suppressant technology and new physiologically-targeted treatments, the possibility to achieve equivalent results to chlorpropham (CIPC) is ‘within reach’, a new study has found.
Looking at novel alternatives to CIPC, Dr Mac McWilliam, research and development director at PepsiCo, said: “We have relied on CIPC for 68 years, but it is time to think differently. Research from Cranfield University has identified combinations of physiologically targeted treatments which confer storage durations equivalent to that of CIPC in processing potatoes.”
These included applications of 1-methylcyclopropene (1-MCP) and targeted ethylene to connect the timing of application of ethylene to the physiological status of the tuber, in short and medium-term storage situations.
Dr McWilliam said: “Ethylene is low cost with good sprout control, but has a risk of increased sugars in many processing varieties. In a number of situations, you see a respiration peak about three days after the onset of the application of ethylene. This means you have essentially woken up the potato, which translates to a sugar spike.
“This sugar spike is where 1-MCP comes in. It is an ethylene inhibitor and it preferentially blocks the pathways leading to conversion of starch to sugars, without impacting sprout suppression. 1-MCP can block this sugar cascade and we can get the nice bright crisp we are looking for.”
Laboratory and plant-scale experiments from 2015-2019 examined commercial processing varieties and assessed sprouting, sugars, fry colour, respiration and weight loss.
By optimising the combination of 1-MCP and ethylene through application timings, the study found by adding 1-MCP after curing but before pull down in a set temperature range, and then following with physiologically targeted ethylene in the cold storage applied at the onset of eye movement, respiration was minimised and any impact on sugars was mitigated.
Dr McWilliam said: “By combining the 1-MCP with the physiologically targeted ethylene we are able to confer three advantageous factors: no sugar accumulation, benefits from sprout control, and a reduction in weight loss equating to about 1 per cent in four months,” he said.
“Across three processing varieties, in the low sugar stability variety we were able to show significant benefit in terms of sugar status and sprout control until February. In our mid-term variety with medium sugar stability we got a similar effect.”
In the long-term storage target where the single modulator was applied there were significant benefits, he added.
“In our mid-term variety we could go right up to the end of May without sugar impact or firmness status and that outperformed our CIPC control. Similarly, with our long-term variety with the highest sugar stability, this was starting to sprout under CIPC, but in our modified treatment it maintained it all the way through to June.”
1-MCP is already used as an ethylene inhibitor in a range of crops in the UK, most commonly in apples.
Dr McWilliam said. “Because of the previous use on other crops, 1-MCP registration could be as close as 2021/2022. There is also opportunity for an emergency permit with enough support, which could bring it forward to next year.”