Effects of livestock and chemical fertilizers on growth, yield, and essential oil of Dracocephalum kotschyi Boiss.

To evaluate the response of Dracocephalum kotschyi Boiss. production to the livestock and chemical fertilizers, an experiment was conducted as a split plot with three replications in 2018 and 2019. The experimental treatments included the control (without fertilizer), chemical fertilizer, and different levels (100, 143, and 250 kg nitrogen ha-1) of poultry (PM100, PM143, and PM250), sheep (SM100, SM143, and SM250), and cattle (CM100, CM143, and CM250) manures. The traits including photosynthetic pigments, leaf area index, plant biomass, and percentage and essential oil yield were investigated. The effects of fertilizer, cutting, and the interaction of fertilizer and cutting were significant on all the triats. In the first cutting, the PM250 treatment produced more photosynthetic pigments than the chemical fertilizer. Also, the SM100 and CM100 treatments caused higher chlorophyll a and total chlorophyll compared to the chemical fertilizer. In the second cutting, the average photosynthetic pigments in the manure treatments were not superior to the chemical fertilizer. In the first cutting, the high level of livestock manures had a higher leaf area index compared to the chemical fertilizer, but in the second cutting, the medium and high levels of poultry manure and high level of sheep manure showed this superiority. In the first cutting, the all livestock manures treatments except CM100 produced the plant biomass similar to the chemical fertilizer, but in the second cutting, the PM143 treatment produced higher biomass compared to the chemical fertilizer. In the first cutting, the essential oil content of SM250 treatment was significantly superior to the chemical fertilizer. In the first cutting, the highest essential oil yield was obtained with the high level of livestock manures, but in the second cutting, there was no significant difference between the essential oil yield of different livestock manures levels and chemical fertilizer. In general, it could be concluded that the high level of poultry manure is a desirable alternative to the chemical fertilizer in D. kotschyi cultivation by creating the favorable conditions for the plant growth.