Smoke-saturated Water and Karrikinolide Modulate Germination,Growth, Photosynthesis and Nutritional Values of Carrot (Daucus carota L.)

Plant-derived smoke is a positive regulator of seed germination and growth with regard to many plant species. Of the several compounds present in plant-derived smoke, karrikinolide or KAR₁ (3-methyl-2H-furo2,3-c]pyran-2-one) is considered to be the major active growth-promoting compound. To test the efficacy of smoke-saturated water (SSW) and KAR₁ on carrot (Daucus carota L.), two separate pot experiments were simultaneously conducted in the same environmental conditions. SSW and KAR₁ treatments were applied to the plants in the form of aqueous solutions of variable concentrations. Prior to sowing, seeds were soaked in the solutions of SSW (25.8 µg L^?1_, 51.6 µg L^?1,103.2 µg L^?1 and 258.0 µg L^?1) and KAR₁ (0.015 µg L^?1, 0.150 µg L^?1, 1.501 µg L^?1 and 15.013 µg L^?1). Percent seed germination, vegetative growth, photosynthesis and nutritional values were the major parameters through which the plant response to the applied treatments was investigated. The results obtained indicated a significant improvement in all the plant attributes studied. In general, SSW (51.6 µg L^?1) and KAR₁ (1.501 µg L^?1) proved optimum treatments for most the parameters. As compared to the control, 51.6 µg L^?1 of SSW and 1.501 µg L^?1 of KAR₁ increased the percent seed germination by 58.0% and 54.4%, respectively. Over the control, the values of plant height and net photosynthetic rate were enhanced by 33.9% and 40.9%, respectively, due to 51.6 µg L^?1 of SSW, while the values of these parameters were increased by 25.2% and 34.0%, respectively, due to 1.501 µg L^?1 of KAR₁. In comparison with the control, treatment 51.6 µg L^?1 of SSW increased the contents of β-carotene and ascorbic acid by 32.7% and 37.9%, respectively, while the treatment 1.501 µg L^?1 M of KAR₁ enhanced these contents by 42.0% and 48.4%, respectively. This study provides an insight into an affordable and feasible method of crop improvement.