The effect of biofertilizer and potassium in reducing drought stress and improving black seed yield

Abstract

A split factorial experiment was performed in the form of a randomized complete block design in three replications in Marvdasht city to investigate the application of mycorrhiza and potassium fertilizer in different irrigation methods of Nigella sativa. Four irrigation levels with 100, 75, 50, and 25% of the field capacity were considered the primary plot, and the application and non-application of mycorrhiza and Potassium fertilizer were considered secondary plots. As the drought stress increased, the number of follicles per plant, the number of seeds per follicle, 1000-seed weight, seed yield, oil percentage, and oil yield decreased. The percentage of Nigella sativa essential oil in irrigation treatment of 75% of the field capacity in the first year of the experiment had a maximum value of 1.89%. As the drought stress increases, the proline content, soluble sugars, and ion leakage increase under moisture stress conditions (25% of field capacity), and the phosphorus, potassium, and relative content of leaf water decreased. The application of mycorrhiza (simple effects) increased Nigella sativa traits, so its application showed a significant difference compared to its non-application. Also, the application of potassium fertilizer (simple effects) compared to the non-application of potassium fertilizer increased seed yield and some traits of Nigella sativa. Interaction effects showed that the application of mycorrhiza under the irrigation treatment of 75% of the field capacity increased Nigella sativa traits and no significant difference was found in some traits with irrigation treatment of 100% of the field capacity. Increasing the drought stress and the irrigation treatment of 25% of the field capacity reduced the efficiency of mycorrhiza and the application of potassium fertilizer. There was no significant difference between the application and non-application of mycorrhiza and the application and non-application of potassium fertilizer for most of the Nigella sativa traits.