The Effect of Drought Stress and Micronutrient of Zn and Mn on yield and Essential Oil of (Cuminum cyminum)

In order to study the effect of drought stress and application of micronutrient of Zn and Mn on yield, yield components and essential oil of cumin medicinal plant, a experiment in split plot arranged in randomized complete block design with three replications conducted in Zahedan city, Iran, in 2012. Drought stress in three levels (including control and stopping irrigation at vegetative and reproductive stages) as main plot and four levels of micronutrients (including control, Zn, Mn and Zn+Mn) as sub plot investigated. Plant height, number of umbrella per plant, number of seed per umbrella, seed weight, seed yield, biomass, essential oil yield and its percentage were measured. Results of statistical analysis showed that stopping irrigation at vegetative stage led to significant reduction in yield and its components. The highest seed yield and biomass with averages of 438.37 and 828.72 kg.ha-1 achieved from control treatment respectively, which had no difference with stopping irrigation at reproductive stage; stopping irrigation at vegetative stage led to decrease of seed yield and biomass about 28.2 and 21.6 percent against control treatment. Essential oil yield of cumin decreased significantly with increasing of drought severity. While micronutrients have no effect on yield of essential oil, but results showed an increase of 22.1% in Zn+Mn against control treatment.