Althaea officinalis is characterized with high genetic diversity, low water requirement and several medicinal properties. However, there are a few studies on seed dormancy breaking methods and the effects of drought stress o A. officinalis yield and physiochemical traits. In the first experiment, 41 seed dormancy breaking treatments were applied in a completely randomized design with 3-replicates in Petri-dish. Among the tested treatments, combined effect of washing and alternative temperatures was the most effective. In the second experiment, the effects of three irrigation regimes (30%, 60% and 80% deplated of soil available water) on nine accessions (Isfahan 1, Isfahan 2, Tabriz, Khomeini Shahr 1, Khomeini Shahr 2, Shahins Shahr, Shiraz 1, Shiraz 2 and Mahallat) were examined. The experiment was conducted, during 2017 and 2018, in the Levark Research Station of Isfahan University of Technology located at 40 km southwest of Isfahan. A. officinalis accessions were evaluated in each irrigation environment and combined analysis of variance over environment basedon RCBD with three replications used. Chlorophyll a, chlorophyll b and carotenoids contents decreased 54%, 84% and 87% respectively while proline content and activity of antioxidant enzymes including catalase and superoxide dismutase increased 182%, 127% and 46% respectively under I 3 relative to level I 1. Drought stress also reduced 1000 grain weight, grain yield and flower yield 24%, 57% and 49% respectively. Whereas, water deficit caused 28, 93 and 300 percent increase in mucilage content of leaves, petals and seeds, respectively. On average and based on enzyme activities , Khomeini Shahr 1, Tabriz and Khomeini Shahr 2 were indentified as the most drought tolerant accessions and Shirz 1 and Shiraz 2 were the most sensitive accessions. Tabriz produced the highest musilage content (225%) on the I3 irrigation regime . The results suggested that reduction of water supply accumulated organic metabolites such as proline and increased the activity of antioxidant enzymes and mucilage contents while caused a reduction in yield and its components. These results suggested that with managed irrigation regimes increase in mucilage contents in this species is possible. Keywords : Medicinal plants, Hollyhock, seed dormancy, drought stress, mucilage
