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Effect of Deficit Irrigation Timing on Sugarbeet

Tarkalson, David D., King, Bradley A.
Agronomy journal 2017 v.109 no.5 pp. 2119-2127
Agricultural Research Service, Beta vulgaris, application timing, crop yield, deficit irrigation, drought, evapotranspiration, growing season, irrigation scheduling, silt loam soils, sucrose, sugar beet, sugar content, water stress, Idaho
Increased water demands and drought have resulted in a need to determine the impact of deficit water management in irrigated sugarbeet (Beta vulgaris L.) production. This study was conducted over 3 yr at USDA-ARS in Kimberly, ID, on a Portneuf silt loam soil. Eight irrigation treatments consisted of crop evapotranspiration (ETc) rates combined with application timing. Treatments were: W1 Even: approximately (≈) 100% ETc evenly throughout the growing season; W2 Even: ≈65% crop evapotranspiration; W2 Early: ≈100% ETc early in season, ≈55% ETc the remainder of the season; W2 Late: rain-fed from emergence to end of July, ≈100% ETc the remainder of the season; W3 Even: ≈40% ETc; W3 Early: ≈100% ETc early in season, ≈25% the remainder of the season; W3 Late: rain-fed through mid-August, ≈100% ETc the remainder of the season, and rain-fed: no post emergence irrigation. Results showed that within deficit irrigation treatments, higher yields were obtained when water was applied evenly throughout the season (Even) or ≈100% of ETc was applied early with deficit irrigation later in the season (Early). Thus, the W2 Even and W2 Early treatments had 31.6, 32.9, and 28.2% greater estimated recoverable sucrose (ERS) yields compared to the W2 Late treatment in 2011, 2012, and 2016, respectively. Across all years, ERS yields increased at rates ranging from 17.3 to 22.0 kg ha–¹ mm–¹ actual crop water evapotranspiration (ETa). Generally, sugarbeet with greater water stress early in the season followed by ≈100% ETc later had lower yields and sucrose content (late treatments).