Research Objective
To use mutagenesis to develop genetic diversity in lentil populations to target additional herbicide tolerances in lentil.
Background
Since lentils compete poorly with weeds and control options are currently limited, Saskatchewan Pulse Growers (SPG) has identified increased herbicide tolerance as a strategic priority and is investing in research initiatives to develop herbicide-tolerant lentil varieties.
During this multi-year project, J4 Agri-Science (J4) increased genetic diversity in lentil populations to uncover mutations conferring herbicide tolerance. The objective of the project was to increase genetic diversity in lentil populations by targeting additional herbicide tolerances that previous studies have shown can be induced by point mutations in certain genes.
The focus of the final year of the project was to test developed populations to identify promising individuals and to confirm tolerance in individuals identified during the Year 1 (2022) and Year 2 (2023) field trials.
Design of Experiment
J4 carried out Year 3 of this project between February 2024 and February 2025. It focused on four lentil populations (two small red, two large green) developed during earlier phases of this project. Four herbicide groups were used to challenge these populations to uncover resistance. In 2024, two additional chemistries were added.
Indoor Seed Increases
In response to promising results of the selected individual plants, small crossing blocks were conducted in the fall of 2023, followed by a larger crossing block in the winter of 2024, to backcross out unwanted mutations while introgressing additional advantageous traits into the populations.
F1 seed was self-fed, and F2 seed that matured in time was grown in a greenhouse heated to 22°C during the day and 20°C at night during 20-hour days. The chemistries of interest were applied using a chemical cabinet, following typical application procedures for each chemical.
Herbicide Challenge Trials
In 2024, five herbicides were used at J4’s field site in herbicide challenge trials.
In the large plot, a four-row planter was used to seed the bulk of three lentil populations at 2-inch intervals in rows spaced 14 inches apart. In contrast, lines developed from selections in 2023 were seeded in rows spaced 28 inches apart to facilitate observation. A second site in the brown soil zone was also used and seeded with a plot seeder.
Three weeks after seeding, all populations were sprayed with post-emergence herbicides of interest at phytotoxic levels. A control strip was left at the beginning of the first row.
Individual plants from all challenge trials were observed for the remainder of the growing season, and promising candidates were flagged, caged, and wrapped with insect netting to protect them from grasshoppers and other biotic and abiotic stresses. Clethodim was applied to all trials to control grasses, and broadleaf weeds were pulled by hand. Plants of interest were individually harvested, and lines were increased in the fall of 2024, crossed to begin stacking promising herbicide tolerances, and advanced for trialling in 2025.
Results
This project had varying levels of success, depending on the chemistry of interest. Survivors were isolated from several herbicide challenge trials and were tested in subsequent trials. Several of the survivors were determined to be escapes rather than tolerant of the tested herbicide. That said, some survivors carried mutations that effectively increased the lentil plant’s tolerance to the target chemistry.
Indoor trialling proved effective in confirming whether the survivor of interest was tolerant of the herbicide or an escape. The indoor procedures developed were instrumental in testing the population segregation developed in this project.
J4 continues to work on introgressing mutations of interest into adapted material, which will be commercialized and available to Saskatchewan’s lentil producers as soon as possible.
Implications for Growers
A multi-herbicide group stack would give the industry the best chance of successful weed control, especially given the high mutation rates observed in kochia and other weeds of significant concern. The ongoing development of herbicide-tolerance traits in lentil could help farmers successfully combat these detrimental weeds.
Future Research
Seed from previously developed populations continues to be increased by J4 and bulked to maintain these populations for use in future herbicide challenge trials.
Future research directions include dose-response trialling, multi-site trialling, backcrossing to increase line adaptation, and crossing to introduce other traits, with the aim of moving promising lines towards commercialization. In addition, procedures still need to be developed for some herbicide groups to determine if indoor application tests can be conducted to select for tolerance.
NOTE: Due to legal restrictions, some details about varieties that have not yet been commercialized must be kept confidential.