Two field experiments were carried out at the Research Farm of Sakha Agricultural Research Station (latitude of 31º 10 N and longitude 30º 93 E, at an elevation of 14 m above sea level), Kafr El-Sheikh Governorate, Egypt in 2021/2022 and 2022/2023 seasons to study the effect of humic acid as a soil amendment and foliar application of trace elements as a Nano fertilizer on growth, yield, and quality of sugar beet (Beta vulgaris var. saccharifera, L.), This work included twelve treatments representing the combinations of three soil application levels of humic acid (without, 2.5 and 5 kg/fed) and spraying canopies with four Nano elements (without, iron, manganese and boron), were separately sprayed at the rate of 100 mg/L after 50, 65 and 80 days from sowing. A complete block design in a split-plot arrangement with three replications was used. The results showed that applying humic acid at a rate of 5 kg/fed increased photosynthetic pigments, leaf area index, peroxidase enzyme activity and yields of root and sugar/fed however, alpha-amino N content decreased in both seasons. Additionally, catalase enzyme activity increased in the first season, compared to adding half humic/fed acid dose (2.5 kg). Fertilizing beet plants with 2.5 kg of humic acid/fed attained lower potassium and sodium content and improved quality index than adding 5 kg of humic acid/fed in both seasons. Moreover, supplying beets with either 2.5 or 5 kg humic acid/fed (without considerable differences) resulted in the highest root sucrose, extracted sugar percentages and reduced sugar lost to molasses %, compared to untreated beet plants in both seasons. Sprayed beet plants with Nano boron, resulted in the highest values of leaf area index, photosynthetic pigments, Peroxidase activity, root and sugar yields/fed in both seasons, with catalase activity in 1st season. Main while, the values of alpha-amino N content and sugar lost to molasses% were reduced in the second season compared to beets sprayed with the rest of the treatments. However, sprayed beets with Nano trace elements had insignificant effects on the quality index, sucrose and extracted sugar percentages in both seasons. The highest root and sugar yields/fed were obtained by fertilizing beets with 5 kg of humic acid along with spraying Nano boron compared to the other combinations in both seasons.

Consequently, the application of nanomaterials significantly enhanced chlorophyll a and b, catalase, sugar lose to molasses% and sugar yield where the highest values were recorded by the application of Fe or Mn nanoparticles with no significant differences between them, however the application of nanomaterials did not significantly affect chlorophyll a and b, catalase activity, sucrose%, extractable sugar%, Na+, α-amino N and root yield in both seasons.