investigating the effect of seaweed extract and humic acid on the quantitative and qualitative performance of sugar beet under water stress

Water stress is one of the major limitations in crop production and performance stability. this study aimed to investigate the effect of biological stimulants on the quantitative and qualitative performance of sugar beet under drought stress. a field experiment was conducted to evaluate the effect of irrigation regimes (irrigation after 80, 160, 240, and 320 mm of water evaporation from the class a pan) and the application of biological stimulants at 5 levels (control, seaweed extract at 3 and 6 kg ha⁻¹, humic acid at 3 and 6 kg ha⁻¹). the results showed that the highest gross sugar (15.99%), extraction coefficient (77.31%), and pure sugar (12.37%) were obtained under irrigation conditions after 240 mm of water evaporation, while the highest levels of sodium (16.4%) and nitrogen (3%) were obtained under irrigation conditions after 320 mm of water evaporation. the use of biological stimulants caused a significant increase in gross sugar and pure sugar and a reduction in sodium and nitrogen compared with the control treatment. the maximum root yield (74.06 t ha⁻¹) and pure sugar yield (8.42 t ha⁻¹) were obtained in the foliar application of 6 kg ha⁻¹ of humic acid under irrigation conditions after 80 mm of water evaporation. in general, 6 kg ha⁻¹ of seaweed extract and 3 kg ha⁻¹ of humic acid under moisture stress conditions reduced sugar beet root impurities such as sodium and harmful nitrogen. as a result, the efficiency of root sugar extraction was significantly improved, and the sugar percentage of molasses was reduced.