This study was carried out at green house on National Research Centre during two successive seasons of 2021-2022 in Giza, Egypt. The aim of this work was to investigate the effect of spraying different concentrations of riboflavin (0, 1000 ppm) on vegetative growth and chemical constituents of Azadirachta indica L. seedlings grown under three salinity concentrations (0, 6000 and 8000 ppm). Our results showed that, spraying riboflavin of derivative (1), lead to increasing both of (plant height, leaves number/plant, stem diameter, branches number/plant, fresh and dry weight of leaves, stems and roots, chlorophyll a, b, a+b and carotenoids, water leaf content and total carbohydrates percentage), while a significant reduction in all the same parameters, were occurred by using high salinity level (8000 ppm). The combined proline and phenols contents decreased by using derivative (1) or derivative (2) riboflavin, compares of treated as the control. The results suggested that Azadirachta indica L. seedlings benefited the application of riboflavin especially under salinity concentrations grown in sandy and clay mixed soil.
Keywords: Growth stimulant; Riboflavin derivatives; Salinity; Ornamental plants; Neem