A field experiment was carried out during rabi season of 2018-2019, at college farm, College of Horticulture, Dr. Y.S.R. Horticultural University, Venkataramannagudem, West Godavari District, Andhra Pradesh. The experiment was laidout in a Randomised Block Design with eleven treatments (viz., T1- NAA @ 50 ppm, T2-NAA @ 100 ppm, T3-GA3 @ 50 ppm,  T4-GA3 @ 100 ppm, T5-Thiourea @ 250 ppm, T6-Thiourea @ 500 ppm, T7-28-Homobrassinolide @ 0.1 ppm, T8-28-Homobrassinolide @ 0.2 ppm, T9-Triacontinol @ 2.5 ppm, T10-Triacontinol @ 5 ppm, T11-(Control) Water spray) and three replications. The treatments were imposed at 30 and 45 DAT in the form of foliar spray. Foliar application of GA3@ 100 ppm (T4) had recorded the maximum plant height (108.20 cm), leaf area (9.53 cm2) and leaf area index (0.74). Foliar application of thiourea @ 250 ppm (T5) had recorded the maximum values with respect to number of primary branches (15.03 plant-1), number of secondary branches (83.40 plant-1), plant spread (1793 cm2 plant-1), fresh weight (376.29 g plant-1), dry weight (103.54 g plant-1) and number of leaves plant-1((298.8). The same treatment (T5) had recorded the highest values with respect to crop growth rate (1.44 gm-2d-1), chlorophyll-a (1.40 mg g-1), chlorophyll-b (0.076 mg g-1) and total chlorophyll contents (1.48 mg g-1) in the leaves.

Foliar application of plant growth regulators viz.,  GA3 -50& 100 ppm,  NAA- 50 ppm &100 ppm, Thiourea- 250 & 500 ppm, 28-Homobrassinolide- 0.1& 0.2ppm, Triacontanol - 2.5& 5 ppm and Control. All the treatments were applied as foliar sprays at 30 and 45 DAT. Days to 50% flowering (46 d) and days to harvest (100.20 d) were found earlier in ajowan with the foliar applications of triacontanol by 5 ppm (T10).The same treatment had recorded the maximum number of umbellate umbel-1(14.20). Foliar applications of thiourea by 250 ppm (T5) had record the highest values  with respect to yield, yield attributing characters viz number of umbels plant-1(228.70), number of seeds umbel-1(183.60), number of seeds umbellate-1(13.50), test weight (1.56 g), seed yield plant-1 (28.50 g), seed yield plot-1 (1425 g), seed yield hectare-1(1583.33 kg), harvest index (69.71%) and quality parameters viz essential oil (3.64%) and protein contents (19.26 mg 100 g-1).