New Research Digs Into Heat Tolerance in Peas - PulsePoint
April 15, 2019
Heat tolerance could further help peas adapt to Saskatchewan’s changing summer temperatures
by Jane Caulfield
As we say goodbye to an extremely cold winter in Saskatchewan, worrying about rising temperatures during the summer months may seem a little odd. For growers, it is a concern that can have a significant impact on their annual yields. This is why a team of researchers, led by Dr. Rosalind Bueckert, Professor of Plant Sciences at the University of Saskatchewan, turned to the Canadian Light Source (CLS) to explore heat resistance in peas.
“Peas and other crops grown in Western Canada are susceptible to high temperature stress during flowering and pod development,” says Dr. Tom Warkentin, Professor of Plant Sciences at the University of Saskatchewan, Plant Breeder with the Crop Development Centre, and co-lead on the study. “More heat leads to a shorter flowering period which leads to less grain yield.”
According to research, temperatures reaching 32 degrees Celsius in the field can cause the abortion of flower buds, flowers, and pods. Similarly, evidence shows that between three to five days of heat above 28 degrees can lead to a decrease in pea yields of up to 25 per cent. This means that as climates continue to change and summer temperatures continue to rise, growers may achieve lower yields, year-over-year.
Pollinating a Solution
In a previous study, the research team found that pollen grains are heat sensitive and pea varieties may vary in pollen robustness, due to the types of fats, oils, and waxes — otherwise known as lipids — in their pollen coats. Using this information, the team designed a new project to explore and understand how heat changes the pollen grains and leaf wax from different varieties of peas.
“Using spectroscopy at the CLS, we were able to track changes in the pollen coat of peas that had been subjected to five days of heat stress,” says Warkentin. “We then compared those samples to ones that had been grown at normal temperatures.”
Results showed biochemical changes in the plant, which explain why one variety was more heat resistant than the other. More specifically, the difference in lipid profile between varieties demonstrates a potential for improving heat tolerance.
“Spectroscopy and other X-ray imaging techniques are minimally invasive, which means we can look at the internal structures of the pea, including a single cell,” says Warkentin. “It provides us with significant information and helps us advance the science in remarkable ways.”
The team was also able to use twodimensional and three-dimensional X-ray imaging (similar to those used in medical imaging) to examine processes that take place soon after pollination and are otherwise difficult to measure using conventional techniques. The results from these imaging studies show that heat stress also causes damage that leads to reduced seed sizes and slowed pod growth.
“This research lays the groundwork to increase pea yields on Saskatchewan farms. Increasing yields of established crops like peas and lentils is one of our key result focus areas that we use to guide our research, market development, and communications investments” says Dr. Dave Greenshields, Saskatchewan Pulse Growers’ Director of Research and Development. “Investments in fundamental research like Rosalind’s are key building blocks that we use to improve returns for growers in the long term.”
According to Warkentin, one of the best yields for peas in Saskatchewan was during a rather cool summer season more than five years ago.
“In recent memory, the highest yielding pea, wheat, canola, lentil, and other crops in Saskatchewan occurred in 2013. It was the summer in which city people said, ‘we did not really have a proper summer,’” says Warkentin. “Why did they say that? Because it was rarely hot that summer. And the result was record crop yields.”
As climates continue to change, however, growers are looking to research and science to help them adapt and continue meeting industry demand. Discovering the potential for heat tolerance in peas is the kind of science that ultimately supports growers in cultivating success in their fields.
Next steps for the team include analyzing the lipids present in pollen coats and pea leaves using spectroscopy once more. They also plan to screen large numbers of pea varieties for heat stress resistance at the CLS. The goal is to eventually create a heattolerant variety of pea that growers can add into their standard crop rotations.
“Planting early is one way that usually helps crops reach flowering before the most extreme heat in the second half of July and early August. In the longer term, we are breeding pea varieties with greater heat tolerance,” says Warkentin.
“We cannot change the weather,” adds Greenshields “but with work like this, we can invest in ways to deal with what nature gives us. We will look forward to seeing this research translated into new heat-tolerant pea varieties.”