Effect of drought stress and harvesting date on yield and essential oil production of anise (Pimpinella anisum L.)

To study the effect of drought stress and harvesting date on yield and essential oil production of Anise (Pimpinella anisum L.), a field experiment was conducted at College of Agriculture, University of Zanjan during spring of 2010. The experiment was conducted as a factorial based on complete randomized block design with three replications. The effects of water stress in three levels including control, drought stress at flowering and grain filling stages and two harvesting dates including harvest at hard dough and maturity stages were investigated. The results showed that the effect of drought stress on seed yield, total dry matter, number of umbrella in plant, 1000-seed weight, harvest index, essential oil percentage and essential oil yield was significant (p≤0.05). Majority of the mentioned traits except essential oil percentage significantly decreased (p≤0.05) under drought stress conditions but essential oil percentage increased. So the highest grain yield (622 kg/ha) and essential oil yield (20.95 kg/ha) were obtained in control treatment (full irrigation). The results also showed that the effects of harvest date on seed yield, 1000-seed weight, total dry matter, essential oil percentage and harvest index were was significant (p≤0.01). The highest seed yield (501 kg/ha) and essential oil percentage (3.85) were obtained in hard dough and maturity stages respectively.