Deficit irrigation for sugarbeet under conventional and no‐till production

Abstract

Abstract Irrigation is important to sugarbeet (Beta vulgaris L.) production and efficient irrigation management is critical for yield, sugar concentration, water use, and environment quality. Two irrigation studies were conducted to investigate sugarbeet response to deficit irrigation under conventional tillage (CT) and no‐till (NT) systems in 2016 and 2018. The irrigation treatments included full irrigation (100% crop evapotranspiration, 100ETc) and deficit irrigation (66% crop evapotranspiration, 66ETc), and two irrigation cutoff dates (15 and 30 d before harvest). Plant population, soil moisture, sugarbeet root yield, sucrose concentration, and impurity value were measured. Although deficit irrigation at 66ETc did not affect the sugarbeet root yield, sucrose concentration, and sugar yield in 2016, it reduced the root yield, sugar yield, and extractable sugar yield by 5.5, 1.2, and 1.2 Mg ha−1 under CT and 12.4, 2.1, and 1.9 Mg ha−1 under NT systems in 2018. Soil moisture in NT showed great depletion at 15‐ and 38‐cm depths in July and August in 2018. Results indicate the potential of implementing a deficit irrigation strategy in sugarbeet to reduce the water supply and increase the water use efficiency, but in‐situ soil moisture sensors should be installed to monitor soil moisture to avoid severe water stress. Stopping irrigation 30 d before harvest slightly reduced the sugarbeet root yield but did not affect extractable sugar yield, suggesting that omitting one irrigation late in the growing season may not reduce root yield and quality. Deficit irrigation in conjunction with a no‐till system could reduce production costs and bring environmental benefits.