Effects of different levels of vermicompost on morphophysiological and essential oil characteristics of Peppermint (Mentha piperita L.) under water deficit regimes

Drought is one of the most important factors limiting plant growth around the world. So it can be used minimum water with using natural fertilizer such as vermicompost and can be caused to reduce water evaporation from soil, protect and storage water in the soil. The interest in plant products has increased considerably all over the world because many herbal medicines are free from side effects since most medicinal plants are consumed raw, proper management of crop production is needed to achieve high quality plants. So in this regard, experiment was done to study the effect of different levels of vermicompost on morphophysiological and essential oil characteristics of Peppermint (Mentha piperita L.) under water deficit regimes.
A pot experiment was conducted as factorial based on completely randomized design with three replications at Gorgan University of Agricultural Sciences and Natural Resources greenhouse during 2016. Treatments were included Irrigation regimes in three levels (100 percent FC, control, 75percent FC and 50percent FC) and vermicompost in three levels (0, 20 and 40percent volumetric). Studied traits were included plant height, internodes distance, fresh and dry weight, number of tillers, leaf water ratio, proline, soluble sugar and essential oil percent. After planting, harvesting and growth characteristics, essential oil, soluble sugar and proline were evaluated with Clevenger, the method of Omokolo and the method of Bates, respectively.
The results showed that internodes distance, fresh and dry weight of shoot, number of tiller and leaf water ratio, were decreased by increasing drought stress. Also, with increasing drought stress, leaf water ratio decreased (2.13 percent) and prolin, soluble sugar and essential oil percent were increased 0.72, 10, 14 and 0.13 percent, respectively. Vermicompost had significant effects on all of morphological and physiological characteristic and this effect was the highest in 40 percent volumetric. Interaction effects of Irrigation regime and vermicompost had significant effects on all of morphological and physiological characteristic except of fresh weight of shoot and number of tillers. Essential oil (0.33 percent) and leaf water ratio (23.71 percent) increased in 40 percent volumetric in 50 percent FC.
Due to the results, it be expressed to reduce chemical fertilities use and achieve to sustainable agriculture, can be adjusted with vermicompost application a lot of part from drought stress effects on Peppermint. Generally, the results showed that by vermicompost application (40 percent volumetric) reduced drought damage on growth characteristics and the most essential oil.