The current work was carried out at the Nursery of Ornamental Plants, Faculty of Agriculture, Minia University, during the two growing seasons of 2021/2022 and 2022/2023, to examine the impact of compost levels (0, 250, 500 and 750 g/pot), chitosan (20 and 40 ppm), thiamine (25 and 50 ppm) treatments and their interactions on vegetative and flowering traits and some chemical constituents of Calendula officinalis, L. plant.
Data proved that all tested vegetative characters (plant height, number of main branches/plant, plant dry weight) and flowering measurements (total number of flowers/plant and total fresh and dry weights of flowers/plant), in addition to some chemical composition like photosynthetic pigments content in fresh leaves and nitrogen, phosphorus and potassium% in dry leaves were significantly increased with rising compost level facing the control. The treatment of 750 g/pot was more efficient in this concern. Also, chitosan and thiamine treatments led to an increase in all vegetative and flower traits as well as photosynthetic pigments and NPK percentages. The treatment of chitosan at 40 ppm was superior to other used treatments.
The best overall interaction treatment for the best vegetative and flowering traits was fertilizing plants with compost at 750 g/pot and sprayed Calendula officinalis with chitosan at 40 ppm.