Effect of water-nitrogen interaction on sugar beet yield under drip irrigation in a semi-arid region

Abstract

The study of the response of sugar crops to water and nitrogen deficit is important in areas where water resources are very limited. This work aims to study the response of sugar beet to water stress and fertilization under different levels of nitrogen fertilizers installed in the semi-arid climate of the Tadla irrigated area. The study focused on four water regimes represented by irrigation at 100%, 80%, 60% and 40% ETc of the water requirements of the beet and four levels of nitrogen fertilization (80 kg N/ha, 160 kg N/ha, 240 kg N/ha and 320 kg N/ha) applied by fertigation with a splitting of input according to the nitrogen assimilation curve by the beet plant. The results of the experiment showed that water stress significantly induced a decrease in leaf area and stomatal conductance, as well as a decrease in root yield. However, a water regime of 80% ETc represents a good compromise between saving water and maintaining satisfactory yields. In conditions of lack of irrigation water, a tolerable level of water stress is 60% to ensure a satisfactory productivity rate. The leaf area and root yield reach their maximum at the level of the 4 water regimes from the dose 160 kg N/ha, also with an approximate optimal dose of 80 kg N/ha for the case of the previous legume crop. Splitting nitrogen inputs helps to limit high concentrations in the soil and delay its migration to depth, thereby reducing losses through leaching.