Targeted irrigation scheduling for hybrid canola seed production under water deficit

Abstract

Field experiments were conducted in Alberta, Canada on targeted irrigation scheduling for hybrid canola (Brassica napus) seed production under water deficit in 2024 and 2025. Supplemental irrigation was applied (0.5 in. per week for three consecutive weeks) on inbred parent lines used for hybrid seed production beginning at targeted growth stages: early vegetative, late vegetative, early flower, late flower, and pod fill. The treatment which received targeted irrigation during early flower yielded most similarly to the nominal treatment (control), which received full water. Treatments that received targeted irrigation during late flower and pod fill stages suffered the greatest yield reduction relative to the nominal treatment. The pattern of treatment effects on seed yield was similar in the two years, with no significant treatment-by-year interaction effect. No differences in thousand-seed weight (TSW) were observed among irrigation scheduling treatments in 2024, although significant differences were observed in 2025. Treatments which received targeted irrigation during vegetative growth stages had a smaller TSW than the treatment which received targeted irrigation during pod fill in 2025. No differences in quality, such as weed presence, weed seeds, dockage or green seed percentages were observed from irrigation treatment effects. Water use efficiency (WUE) was different between treatments, with the deficit treatments achieving higher WUE than the nominal treatment.