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. پرونده مقاله

The effects of root temperatures (25, 35 and 45°C) and temperature duration (30, 60 and 90 min) on net photosynthesis rate, stomatal conductance and transpiration rate in Tradescantia pallida were investigated. The experiment was conducted under controlled conditions with factorial arrangement based on a completely randomized design (CRD) and four replications. Result showed that, net photosynthesis rate was not significantly different between plants treated with 25 and 35°C. However, aperture area and width increased at 35°C and declined sharply at 45 °C as compared with that at 25 °C. Net photosynthesis rate and stomata1 conductance of plants treated with 45°C decreased to 76 and 68%, respectively, as compared with those at 35°C. Stomatal aperture area of plants treated with 35°C was 27% and 320% higher than those treated with 25 and 45°C, respectively. Stomatal resistance of plants treated with high temperature (45°C) were higher (174%) than those treated with 35°C. In 35 °C, aperture area of plants after 30 min was 61% and 45% higher than those after 60 and 90 min exposure, respectively. The results revealed that, a heat shock of roots at 45°C could lead to a significant decrease in stomatal conductance (by 81%) and transpiration rate (by 60%) as compared with those at 35°C. Overall, the results suggest that the root temperature affects leaf gas exchange and stomatal behavior and has to be taken into account in plant production system, in particular, hydroponics. پرونده مقاله