Posted 16 July 2014
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Helping growers to reduce radish harvest losses is one of the aims of a three-year research project being conducted at Harper Adams University.
Researcher Rachel Lockley is investigating the environmental and physiological reasons why radishes split, which will in turn help UK growers to reduce yield losses and improve the way in which they handle the crop pre- and post-harvest.
The project, in collaboration with radish producer G’s and funded by the Horticultural Development Company (HDC), began by investigating the impact of irrigation during growth.
29-year-old PhD student Rachel, who is working alongside Principal Lecturers Dr Jim Monaghan and Dr Ivan Grove, said: “There hasn’t been a lot of research into radishes, particularly the small red European varieties, yet there can be up to a 30% loss during and post-harvest due to splitting.
“After consulting a research paper into the larger white radishes and also speaking to growers, it became apparent that the radishes split more after periods of high rainfall.
“This led me to research the effect of irrigation. I found that high levels of water during growth do affect splitting. Water also has an effect post-harvest, as it makes the radishes more susceptible to damage from dropping, puncture and crushing.”
These experiments showed that growing radishes at a high water content led to a 65% split rate, whereas growing them at a low level resulted in just 2% splitting.
Rachel, from Leicester, added: “I then wanted to see if there was a particular growth stage that is most affected by water.
“I found that around day 17, an interesting stage known as ‘secondary thickening’ occurs and this is when all pre-harvest splits happen.
“This process is when the outer surface of the radish ruptures and sloughs away to reveal the periderm. I was then able to link this to the water content, so the water content on day 17 is what determines how much the radish splits later on.”
The water content and firmness of the radish at harvest, and during post-harvest handling, is also thought to influence susceptibility to splitting.
Rachel tested radishes with different water contents using impact and puncture tests, with results showing that less force was needed to puncture those with higher moisture contents, meaning they would be more likely to split.
It is hoped that Rachel’s findings will help farmers to reduce yield losses by encouraging them to manage water levels in the fields. Reducing the number of split radish will improve retail and customer confidence in the product.
As Rachel’s research has also shown that radishes with a lower water content are less likely to split post-harvest, this will also help farmers to improve the way in which they handle the crop.
To read the full project report and grower summaries on this project, visit www.hdc.org.uk and search for CP 083