Study of two hybrid lily (Longiflorum×Asiatic) cultivars ʻNashvilleʼ and ʻMerluzaʼ defensive some mechanisms against drought stress

In this research, to study the effect of drought stress on the morpho-physiological traits of two hybrid cultivars of lily, ʻMerluzaʼ and ʻNashvilleʼ, a factorial, completely randomized design-based experiment with four replicates was performed with potted plants in the experimental greenhouses of the department of Horticultural Science, Faculty of Agriculture, Agricultural Sciences and Natural Resources, University of Khuzestan. The experimental factors included four irrigation levels (irrigation at the rate of 100, 80, 60, and 40% rate of field capacity) and two lily cultivars, ʻNashvilleʼ with yellow, and ʻMerluzaʼ with white flowers. The results indicated that the reduction of irrigation rate had significant impact on the evaluated traits. Stalk height and the number of flowers reduced with the reduction of soil water content, whereas the fresh: dry weight ratio of petal increased. However, no significant difference was found in this trait between 80 and 100% rate of field capacity. The activity of catalase antioxidant enzyme, increased as the irrigation rate decreased, however, this increase in ʻNashvilleʼ was higher than ʻMerluzaʼ. Although with both cultivars, catalase activity and soluble carbohydrate level were higher under drought stress, severe stress at 40% rate of field capacity led to reduced protein content, ramped down catalase activity and diminished rate of soluble carbohydrates. Generally, the results of the present study indicated that although both cultivars well tolerated mild drought stress of 80% rate of field capacity, severe stress at 40% rate of field capacity led to serious damages in both lily cultivars. Also, lily ʻNashvilleʼ cultivar expressed more tolerance than ʻMerluzaʼ cultivar via the mechanisms such as increased carbohydrate content and peroxidase activity that resulted in the reduced peroxidation of lipids.