Efficacy of endophytic bacteria for improving the growth and yield of black cumin (Nigella sativa L.)

Black cumin (Nigella sativa L.) is an annual medicinal herb of ancient time with fine linear leaves and has pale bluish and white flowers. It belongs to the buttercup family which contains many medicinal constituents. The most important chemical constituent present in the seeds and fruits of black cumin plant is thymoquinone which is used medicinally as an anti-cancer agent, anti-diabetic agent, anti-inflammatory agent and anti-oxidant agent. A pot experiment was conducted to investigate the effect of endophytic bacteria for improving growth and yield of Nigella sativa L. Pre-isolated endophytic bacterial strains i.e. AS-3, MN6, MW4C, and their consortium were used to evaluate their potential besides untreated (control). The bacterial inocula was prepared in 10% Tryptic soy broth (TSB) and applied as soil and foliar application method. Recommended dose of N, P, K fertilizers at the rate of 90, 60 and 30 kg per ha was applied, respectively. Each treatment was replicated three times and different growth and morphological parameters were measured. The data of these parameters was analyzed using statistical software SPSS version 22.0. So it is concluded from results, that all treatments showed significant results with respect to control. Among treatments, treatment no. 2 (strain AS-3) and 5 (consortium) showed more significant effect with respect to control and other two treatments. Treatment No.5 (consortium) increased root and shoot length 50% and 41 % in foliar application method of bacterial strains inoculation and 58% and 53% in soil application method of bacterial strain inoculation. Whereas T2, T3 and T4 increased root and shoot length 32%, 20% and 13% in foliar application method and 38%, 25% and 17% in soil application method. Similarly, consortium increased highest yield in both foliar and soil application methods which is 39% and 50% with respect to control. Whereas, T2, T3 and T4 increased yield 33%, 17% and 7.9% in foliar application method of bacterial strains and 43%, 22% and 11% in soil application method. Endophytic consortium also showed good antioxidant properties with having total flavonoid (TF) 58% and 48% in foliar and soil inoculation method and total phenolic (TP) content 37% and 41% in foliar and soil application method with respect to control. Between these two inoculation methods soil application performed better.