Soil and water salinity substantially constrain crop and biomass production. To investigate the changes in morphological parameters of lisianthus (Eustoma grandiflorum) cultivars under CaCl2 salinity conditions a greenhouse experiment was conducted. Cultivars namely, ‘Champagne’ (C1), ‘Lime Green’ (C2), ‘Blue Picotee’ (C3) and ‘Pure White’ (C4), were subjected to salt stress (0–30 mM CaCl2) in a washed sand culture and the morphological responses were measured. The results showed that salinity affected all of the considered parameters, so that, as salinity levels increased, plant height, shoot fresh and dry weight and leaf area in all cultivars decreased, while, root length, root fresh and dry weight and root: shoot length ratio increased. However, the changes in Pure White and Lime Green were less than in ‘Champagne’ and ‘Blue Picotee’. Theregression analysis of the relationship between CaCl2 salinity levels and seedlings height or root: shoot length ratio defined two groups with different slope coefficients: C1 and C3 as salt sensitive cultivars and C2 and C4 as salt tolerant cultivars. The results showed that salinity threshold of C1 and C3 was 25 and 30 mM CaCl2 respectively, while C2 and C4 in 30 mM CaCl2 showed no significant differences with control. The results suggests that C2 and C4 could be recommended as resistant cultivars due to attain higher growth, water balance, shoot fresh and dry weight and leaf area in response to CaCl2 salinity compared with C1 and C3. Manuscript profile

Water stress is one of the main factors of severe damage and limitation of plant production in Iran. The paper reports a pot experiment conducted by using a factorial experiment based on a completely randomized design with three replications (each replication composed of four pots) to compare the physiological and biochemical characteristics of two varieties of tuberose (double- and single-flower) for their tolerance to water stress. Three water stress levels, including no stress (W1 = 90% of FC), moderate stress (W2 = 75% of FC) and severe stress (W3 = 60% of FC), were applied throughout the experiment.Physiological traits including relative water content (RWC) and electrolyte leakage (EL) and biochemical traits including total chlorophyll (Chl), carotenoid (Car) contents, proline, malondialdehyde (MDA), antioxidant enzymes activity (SOD, APX, and CAT), photosynthesis rate (A), transpiration rate (E), and stomatal resistance (rs) were investigated. Results showed that the physiological and biochemical characteristics of the tuberose plants were highly affected by the application of water stress. MDA and EL showed a significant correlation with most physiological characteristics. Water stress caused significant increases in RWC, A, E, rs, Chl, APX, and SOD activities of the leaves of the single-flower cultivar. CAT, MDA, and proline content in the leaves of the double-flower cultivar were significantly higher than those in the leaves of the single-flower cultivar, regardless of water treatments. The results showed that the single-flower cultivar grew better than the double-flower one under stress conditions. Manuscript profile