Soil water extraction pattern and water use efficiency of spring canola under growth-stage-based irrigation management

Authors: KATUWAL, KRISHNA - University Of Georgia; CHO, YOUNGKOO - Eastern New Mexico University; SINGH, SUKHBIR - Texas Tech University; ANGADI, SANGAMESH - New Mexico State University; Begna, Sultan; STAMM, MICHAEL - Kansas State University

Submitted to: Agricultural Water Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/22/2020
Publication Date: 5/18/2020
Citation: Katuwal, K.B., Cho, Y., Singh, S., Angadi, S.V., Begna, S.H., Stamm, M. 2020. Soil water extraction pattern and water use efficiency of spring canola under growth-stage-based irrigation management. Agricultural Water Management. https://doi.org/10.1016/j.agwat.2020.106232.
DOI: https://doi.org/10.1016/j.agwat.2020.106232

Interpretive Summary: A two-year study was conducted to assess soil water extraction pattern and water use efficiency of spring canola under deficit irrigation strategy. Three canola cultivars (H930’, ‘H955’ and ‘L140’) were grown under full season irrigation (FI), no irrigation at the vegetative stage (VS), no irrigation at the reproductive stage (RS) and dryland (DL). Treatments VS and FI extracted similar amount of total water from planting to harvest in wetter year of 2015. However, during same growth period of 2016 with drier condition, VS extracted extra water from soil than FI. Water extraction during reproductive stage in 2016 was similar between FI and VS with most of the extra water extracted was utilized during vegetative stage when irrigation was skipped in VS. Canola sustained vegetative growth utilizing soil water extraction and efficiently utilized irrigation received during reproductive stage to reduce seasonal evapotranspiration in VS compared to FI. Treatments RS and DL reduced seasonal ET, but this resulted in oil content reduction by an average of 11 and 13 % compared with FI in 2015 and 2016, respectively. The VS had similar oil content as FI and optimized water use efficiency for biomass (WUEpb), seed (WUEsy) and oil (WUEoy) yields. Cultivar L140 consistently produced the greatest WUEpb in both years and 34 and 36 % greater WUEsy and WUEoy in 2016 compared to the other cultivars, respectively. Adopting spring canola cultivar L140 and skipping irrigation during vegetative stage could maximize water productivity in water deficit conditions of the Southern Great Plains (SGP).

Technical Abstract: The rapid depletion rate of the Ogallala aquifer threatens agriculture sustainability in the U.S. Southern Great Plains (SGP). Adoption of drought tolerant crop with suitable irrigation strategy is critical to improve water use efficiency and sustain crop production in the region. The objective of the study was to assess soil water extraction pattern and water use efficiency of spring canola (Brassica napus L.) under deficit irrigation strategy (DI). Three diverse canola cultivars (H930’, ‘H955’ and ‘L140’) were grown under four different irrigation treatments; full season irrigation (FI), no irrigation at the vegetative stage (VS), no irrigation at the reproductive stage (RS) and dryland (DL). Treatment VS extracted similar amount (20 mm) of total water from planting to harvest as FI in wetter year of 2015. However, VS extracted 10 mm of extra water from soil depth down to 1.6 m until harvest compared to FI in drier year of 2016. As water extraction during reproductive stage in 2016 was almost similar (70 and 67 mm in FI and VS, respectively) in VS and FI, most of the extra water extracted was utilized during vegetative stage when irrigation was skipped in VS. Canola sustained vegetative growth utilizing soil water extraction and efficiently utilized irrigation received during reproductive stage to reduce seasonal evapotranspiration (ET) in VS compared to FI. Treatment RS and DL also reduced seasonal ET, but they reduced average 11 and 13 % oil content compared to FI in 2015 and 2016, respectively. The VS had similar oil content as FI and optimized water use efficiency for biomass (WUEpb), and seed (WUEsy) and oil (WUEoy) yields. Among cultivars, L140 consistently had the greatest WUEpb in both experimental years and 34 and 36 % greater WUEsy and WUEoy in 2016 compared to both H930 and H955, respectively. Adopting spring canola cultivar L140 and skipping irrigation during vegetative stage could maximize water productivity in water deficit conditions of the SGP.