Response of quantitative and qualitative yield of ajwain (Carum copticum L.) to irrigation cut-off in different nutritional regimes

To investigate the response of quantitative and qualitative yield of ajwain (Carum copticum L.) to the irrigation cut-off in different nutritional regimes, an experiment was conducted as split-plot in a randomized complete block design with four replications at the research farm of Sarvestan Agricultural Jihad Organization, Fars province in 2019. The factors consisted of irrigation as the main factor at two levels (optimal irrigation and irrigation cut-off at flowering stage) and nutritional regime as the sub-factor at six levels (control, mycorrhiza, 15 ton.ha-1 manure, 15 ton.ha-1 manure + mycorrhiza, 30 ton.ha-1 manure, and 30 ton.ha-1 manure + mycorrhiza). The irrigation cut-off treatment reduced the plant height, number of umbrellas per plant, number of seeds per umbrella, 1000-seed weight, seed yield, biological yield, essential oil percentage, and essential oil yield by 30.65, 37.25, 46.12, 43.40, 24.40, 41.78, 19.68, and 52.86%, respectively compared to the optimal irrigation. The use of manure and mycorrhiza significantly increased all the mentioned traits. Moreover, the interaction of irrigation and nutritional sources treatments significantly affected only the percentage and essential oil yield. The highest percentage (2.80%) and essential oil yield (15.02 kg.ha-1) was observed in the 30 ton.ha-1 manure + mycorrhiza and optimum irrigation treatment. The lowest essential oil percentage (1.60%) was obtained in the control and optimum irrigation treatment and the lowest essential oil yield (4.62 kg.ha-1) resulted from the control and irrigation cut-off treatment.