To study the effect of drought stress and harvest time on some morphological traits of chamomile (Matricaria chamomilla L.), this experiment was conducted as split plot in time in the form of a randomized complete block design with three replications. The main factor was irrigation after 60, 90, 120 and 150 mm evaporation from an A class pan, and the sub factor was harvest. Analysis of variance indicated that drought stress significantly affected stem height and root yield at P≤0.01. The interaction of drought stress × harvest had significant effect on dry flower yield, stem height and stem yield at P≤0.01, and on leaf yield at P≤0.05. The harvest had also a significant effect on the number of lateral branches at P≤0.01. Mean comparison showed that the highest stem height (62.84 cm) and flower yield (137.13 kg/ha) were achieved in 90 mm evaporation × the second harvest. The highest number of lateral branches (7.5 branches/plant) and the highest stem yield (362.6 kg/ha) were achieved in 90 mm × the first harvest. In 60 mm × the second harvest, leaf yield was the highest (166.29 kg/ha). All measured traits were the lowest in 150 mm × the second harvest. Regarding the results of this experiment and the importance of chamomile flower yield and essential oil yield, the mild drought stress (90 mm) is advised for chamomile production.
