University of Saskatchewan researcher aims to reduce fertilizer use through plant cross-breeding

A strong source of protein and fibre, peas are a staple in many diets and are appearing more frequently in products such as plant-based meat substitutes and bakery goods. University of Saskatchewan (USask) PhD student Loveleen Dhillon has dedicated her doctoral research to investigating how to improve nitrogen fixation to optimize pea crop yields in Canada.

Nitrogen is a crucial nutrient for plant growth and development in agriculture. Canada is the top producer and exporter of field peas in the world, with Saskatchewan being home to 54 per cent of pea growing area.

″Canadian agriculture relies heavily on inorganic nitrogen fertilizers to achieve higher yield in crops,″ said Dhillon, whose research is being conducted in the USask College of Agriculture and Bioresources. ″These nitrogen fertilizers are one of the most expensive and energy-intensive inputs in our agricultural systems.″  

Although these fertilizers come with financial costs for producers, they also come with environmental concerns related to nitrous-oxide emissions from application.  

″There is a critical need to reduce nitrogen fertilizer usage in Canadian agriculture,″ said Dhillon.

To address this need, Dhillon’s study examines how nodules on the roots of the pea plant hold onto nitrogen and investigates possible genetic combinations of pea varieties that can be bred to increase this ability.  

The work is supervised by Dr. Tom Warkentin (PhD), a USask plant sciences professor and Ministry of Agriculture Strategic Research Program Chair in Pulse Crop Breeding and Genetics.  

″We tested pea breeding lines in multiple environments in Saskatchewan for their nitrogen fixing and agronomic performance,″ said Dhillon. ″We are evaluating 220 pea varieties originating from different parts of the world for their nitrogen fixation potential and adaptation under Saskatchewan environments.″

The pea breeding lines in this study were generated at the USask Crop Development Centre. The idea is to take higher-performing pea varieties from other parts of the globe and combine them with Saskatchewan crops to increase production while creating heartier plants that require less nitrogen fertilizer.  

″By crossing top-performing and Saskatchewan-adapted pea varieties (high yielding but low nitrogen fixation) with pea nodulation mutants (low yielding and high nitrogen fixation), our study is the first study that involves estimating the potential of nitrogen fixation of a large number of pea breeding lines under actual field conditions,″ said Dhillon.

She said achieving higher nitrogen fixation in pea plants without reducing seed yield makes peas an attractive and profitable choice in Western Canadian cropping systems.

Another part of the study examines pea root architecture systems to identify potential structures that may hold onto nitrogen more efficiently.

″I had the opportunity to work with the team at the Global Institute for Food Security under the supervision of Dr. Leon Kochian (PhD) and his team to associate root architectural traits with nitrogen fixation potential in peas. I am also working alongside USask research officer Dr. Kishore Gali (PhD) to identify genes that regulate nitrogen fixation in peas. I am currently analyzing and interpreting data from these experiments,″ Dhillon said.

Benefits of this research include the potential to reduce dependance on chemical fertilizers, to improve soil health, to reduce crop production cost and to increase protein content of pea seeds.

″This project will directly contribute to the (USask) mission to improve food security and long-term sustainability,″ said Dhillon, who expects to complete her PhD in 2023.

The research is supported by the College of Agriculture and Bioresources, the Saskatchewan Ministry of Agriculture, and the Western Grains Research Foundation.