A field experiment was conducted to study the effect of foliar spray of ascorbic acid (50 and 100 ppm), benzyl adenine (50 and 100 ppm) and paclobutrazol (25 and 50 ppm) on growth, yield and some physiological parameters of (Helianthus annuus var. Sakha 53). Ascorbic acid was more effective than other treatments in enhancing growth parameters during stage I, while benzyl adenine was most effective during stage II. Paclobutrazol seemed to be less effective regarding growth characteristics. All doses applied tended to increase photosynthetic pigments, total soluble carbohydrates and soluble proteins of sunflower plants. The changes in proteolytic, amylolytic and lipolytic activities were also recorded. This was associated by improving yield quality and the nutritional value of the seeds. The effect of paclobutrazol was superior to that of ascorbic acid, benzyl adenine on increasing yield components. The highest lipid % was recorded by 50 ppm of ascorbic acid, whereas the highest carbohydrates and proteins of the yielded seeds were observed with plants treated with 100 ppm benzyl adenine.