Evaluation of four chamomile species under late season drought stress

To examine the genetic variation for drought stress in chamomile, eight accessions belonging to four species were evaluated under both field and greenhouse conditions using normal and late season drought stress. In the field experiment drought stress were initiated with irrigation cease at the commencement of flowering time. In greenhouse experiment, irrigation carried out at flower initiation when soil moisture reached to 80% and 50% of field capacity in control and drought stress treatments respectively. Orthogonal comparison showed high inter-and intra-species variation for all studied traits. In both experiments, drought stress caused significant reduction of flowering period, maturity time, flower number per plant, flower diameter, flower fresh and dry weight per plant, plant fresh and dry weight and plant relative water content. In field condition under both control and drought stress Gorgan1 accession (Anthemis alltissima) showed the highest flower fresh and dry weight. In greenhouse experiment, Isfahan (Matricaria chamomilla) and Mashhad (Tripleurospermum sevance) accessions produced greater flower yield and total dry mater under control and drought stress conditions, respectively. Minimum reduction due to drought stress for this two traits in the field experiment was for Ilam2 (Anthemis psedocotula) and in greenhouse experiment was for Ilam1 (Anthemis psedocotula) accessions. The maximum reduction rate due to drought stress in most genotypes was related to plant and flower fresh and dry weight. Tripleurospermum sevance species showed less reduction in fresh and dry flower weight when encountered to drought stress, hence it is more drought tolerant as compared to other investigated chamomile species.