Effect of GA3 and NAA on growth, physiological parameters, and bioactive constituents of Ammi majus L.

Coumarins, the naturally occurring benzo-alpha-pyrone derivatives, are important group of secondary plant -metabolites derived from phenylalanine metabolism. Two net-house experiment was carried out concurrently to examine the effects of Gibberellic acid (GA3) (Experiment 1) and naphthalene acetic acid (NAA) (Experiment 2) on growth and physiological parameters, and active constituents of Ammi majus, which is a medicinally important plant rich in coumarins and various flavonoids, alkaloids, and terpenoids. Foliar-spray treatments, consisting of increasing concentrations of GA3 (0, 50, 100, 200, and 400 mg L-1) and NAA (0, 25, 50, 100, and 200 mg L-1) were applied at 45 days after sowing. Application of both of the PGRs improved all of the pa-rameters significantly. The best results were obtained at 100 mg L-1 of GA3 (Experiment 1) and 50 mg L-1 of NAA (Experiment 2) in terms of growth characteristics (plant height, fresh weight and dry weight), physiological parameters (photosynthetic pigments, chlorophyll fluorescence, and activities of nitrate reductase and carbonic anhydrase) and seed-quality parameters (bioactive constituents). The most effective treatments, viz. 100 mg L-1 of GA3 (Experiment 1) and 50 mg L-1 of NAA (Experiment 2), resulted in appreciable increases in seed bioactive ingredients. The primary components were Methoxsalen, 7 H-furo [3,2-g] [1] benzopyron-7-one, 4, 9 dimethoxy, and p-camphorene, according to gas liquid chromatographic analyses. In comparison to the control, foliar treatment of GA3 (100 mg L-1) considerably increased the plant's shoot length (29.54%), root length (27.58%), fresh weight (36.78%), and dry weight (41.71%). Whereas, 50 mg L-1 of NAA enhanced these growth attributes by 31.12%, 32.61%, 34.84%, and 30.32%, respectively, in comparison to the control. Foliar application of 100 mg L-1 of GA3 increased the chlorophyll fluorescence (51.8%) as well as total content of chlorophyll (39.81%), and carotenoids (47.53%), in contrast with the control. Comparing the control, 50 mg L-1 of NAA enhanced the chlorophyll fluorescence, and total content of chlorophyll and carotenoids by 42.3%, 30.92%, and 27.81%, respectively. The best foliar-application treatments of 100 mg L-1 of GA3 and 50 mg L-1 of NAA were most effective for NR activity, surpassing the control by 27.7% and 21.5%, respectively. The largest increase in leaf CA activity was observed due to 100 mg L-1 of GA3 and 50 mg L-1 of NAA, which exceeded the control by 24.6% and 19.04%, respectively.