Improving physiological traits, yield and essential oil of cumin (Cuminum cyminum L.) via application of phosphorus bio-fertilizers and supplementary irrigation under dryland condition

In order to investigate the effects of different levels of supplementary irrigation and bio-fertilizers on some physiological traits, yield, and essential oil percentage of medicinal plant cumin (Cuminum cyminum L.), an experiment was conducted as split-plot in a randomized complete block design with three replications in the research field of Kohgiluyeh and Buyer-Ahmad Agricultural and Natural Resources Research and Training Center in 2017. The main plot included supplementary irrigation (complete rainfed conditions, supplementary irrigation at 50% flowering and at the start of seed formation) and the subplot included bio-fertilizer (no phosphorus bio-fertilizer, mycorrhiza Glomus mosseae, phosphorus bio-fertilizer, and combination of mycorrhiza and phosphorus bio-fertilizer). The application of supplementary irrigation with bio-fertilizer increased the total chlorophyll and carotenoid and decreased the proline content. Phosphorus bio-fertilizer also increased catalase enzyme activity in the plant. The effects of supplementary irrigation and phosphorus bio-fertilizer on the number of umbrella per plant, plant height, 1000-seed weight and the number of seeds per umbrella were significant. The highest amount of 1000-seed weight (2.55 g), seed yield (622.4 kg ha-1), biological yield (1252 kg ha-1), and essential oil percentage (54.86%) was obtained in the mycorrhiza treatment together with the phosphorus bio-fertilizer. In general, the results showed that using phosphorus bio-fertilizer, mycorrhiza, and supplementary irrigation can improve physiological traits, yield, and essential oil of cumin under rainfed conditions.