This study was carried out to evaluate the effects of dry yeast (0.4 and 0.8%), salicylic acid (150 and 300 ppm) and ascorbic acid (150 and 300 ppm) as a spray application on black cumin plants to determine their effects on plant height, number of branches/plant, stem diameter, root length, capsule number/plant, capsules weight/plant, seed weights/plant, seed yield/fed, fixed oil percentage and oil yield/fed during both seasons. The highest concentration of each substance showed superiority in comparison with the lowest concentration of the same substance and the control. Salicylic acid at rate of 300 ppm showed significant increase in plant height, seed weight, seed yield and fixed oil yield. Meanwhile, Ascorbic acid at rate of 300 ppm presented significant increment in number of branches/plant, capsules number/plant, capsules weight and oil percentage. Dry yeast at rate 0.8% caused an increase in the root length which calculated at the first season as 17.15 cm and at the second season as 16.45 cm.