Regulated Deficit Irrigation at Special Development Stages Increases Sugar Beet Yield

Abstract

Core Ideas Different growth stages of drip‐irrigated sugar beet can bear different water deficit level. The canopy development stage is the most water‐sensitive period of the sugar beet. Regulated deficit irrigation could increase beet yield and reduce the consumption of water resources in arid land. ABSTRACTThe shortage of water resources promotes the development of water saving irrigation in arid land. Regulated deficit irrigation (RDI), as one of the water‐saving irrigation technologies through applying a certain amount of water stress to the crops to promote the distribution of the photosynthate of crops to the needs of the tissues and organs, can save water and may increase yield. Our study evaluated the effect of the RDI on the sugar beet (Beta vulgaris L. cv. Beta356). Seven irrigation treatments were applied based on the growth stages of sugar beet (canopy development, storage root development, and sugar accumulation) and water deficit levels (30, 50, and 70% of field capacity [FC]). The yield, quality, sugar yield, irrigation water use efficiency (IWUE), and agronomic physiological traits of sugar beet were evaluated. Moderate water deficit (50% of FC) during canopy development increased sugar yield by 27% compared with the control (70% of FC during the whole growth stages). Severe (30% of FC) water deficit increased sugar yield by 45% during storage root development, and by 55% during sugar accumulation. The RDI during canopy development and storage root development inhibited leaf growth but did not affect yield. Malondialdehyde content and relative conductivity increased significantly when soil water content dropped to the irrigation threshold levels (i.e., 30% and 50% of FC) before rehydration during canopy development. After rehydration, there were significant increases in peroxidase activity and proline content (indicators of antioxidant defense and osmotic stress). Our results indicated that RDI increased yield at 30% and 50% of FC during three growth stages (canopy development, storage root development, and sugar accumulation) of sugar beet, which reduced irrigation water requirements. RDI could be applied as a strategic action for crop sustainability and water saving in arid land.