Effect of Irrigation and Planting Date on the Selected Morphophenological and Quality Traits of Ajowan (Carum copticum BENTH. & HOOK.F.)

In order to study the effects of irrigation and planting date on selected traits of ajowan (Carum copticum BENTH. & HOOK.F.) an experiment was conducted in two successive conducive seasons of 2009/2010 and 2010/2011 in Birjand. The experimental design was a split plot based on randomized complete block with three replications. In the present study, two irrigation treatments (irrigation termination with flowering onset and complete irrigation) and six planting dates (Dec 6th,  Dec 21st, Jan 5th, Feb 29th, Mar 30th and Apr 30th) were considered as main plot and subplot, respectively. As results indicated, the drought stress significantly reduced seed and essential oil yield, but had a non significant effect on the germination percent. Moreover, there was a nil effect on the morphological characteristics of the plants. It was interesting to note that the late planting date caused seed yield, number of umbels per plant, number of umbellules per inflorescence, plant height, number of branches per plant, essential oil percentage and the length of the vegetative growth period to decrease, but there was nil effect on the essential oil yield and the germination percent. In fine, the results indicated that water stress not only caused the essential oil percent and plant performance to decrease, but also influenced early plantings to have more seed yield and essential oil percent.