Exogenous application of ascorbic acid improves physiological and productive traits of Nigella sativa.

For thousands of years, plants have been utilized for medicinal purposes. For its naturally existing antibacterial properties, is one of the most researched herbs. A study was conducted during rabi 2020-21 at The University of Haripur in order to evaluate the potential of ascorbic acid as plant growth enhancer. Two concentrations of ascorbic acid i-e 350 μm and 400 μm were sprayed along with control and water only spray on crop. The study was arranged in RCBD two factor factorial arrangement. Factor A: ascorbic acid concentrations along with control and water spray, factor B: Growth stages (Stage1 = 40 days after sowing, Stage 2 = 80 DAS, Stage 3 = 120 DAS, Stage 4 = 40 + 80 DAS, Stage 5 = 40 + 120 DAS, Stage 6 = 80 + 120 DAS, Stage 7 = 40 + 80 + 120 DAS). Crop was sown in first week of November. Results reviled that chlorophyll content, fixed oil content, 1000 seed weight, grain yield, Photosynthetic rate (μ mole ms), Transpiration rate (mmole ms), photosynthetic water use efficiency, Internal CO concentration () of leaf tissue and Stomatal conductance (mmole ms) were significantly affected by ascorbic acid concentrations and stage of application. Crop growth rate increased by 19.88% and 17.29%, chlorophyll by 12.3% and 11.2%, fixed oil by 11.7% and 9%, grain yield by 10.29% and 9.8%, harvest index by 4% and 5.7% photosynthetic rate by 33%, 20% and stomatal conductance by 24.24% and 24.25 with application of ascorbic acid @ 350 μm, over control and water spray respectively. On the basis of these results it is concluded that application of ascorbic acid at the rate of 350 μm, followed by ascorbic acid at the rate of 400 μm significantly improves black cumin () yield and production. Hence it is recommended to apply ascorbic acid at the rate of 350 μm at 40 + 80+120 days after sowing of crop for obtaining maximum results.