Document Type : Research paper
Authors
Department of Horticultural Sciences, Garmsar Branch, Islamic Azad University, Garmsar, Iran
Abstract
Salinity stress was imposed on Calendula officinalis L. by potassium chloride (KCl) and sodium chloride (NaCl) salts. This study evaluated the ameliorative effects of polyamine foliar application on growth indices and physiological traits of Calendula officinalis L. under salinity stress. A factorial experiment was arranged in a completely randomized design with three replications. The experiment was conducted in a commercial greenhouse in Pakdasht, Iran (2021). The treatments included salinity stress induced by NaCl and KCl salts (0, 50 and 100 mg L-1) and putrescine and spermine foliar applications (0, 1 and 2 mM). The results showed that the treatments had a significant effect on the measured variables. Increasing NaCl and KCl levels decreased the value of each variable, except for proline and superoxide dismutase activity. Putrescine and spermine foliar applications mitigated the effects of salt stress and improved the evaluated traits. The highest fresh and dry shoot weight (15.59- 3.58 g), plant height (38.70 cm), leaf count (23), and flower count (12.50) were observed in the control. Also, the highest root fresh weight (5.17 g) and root volume (4.60 cm3) were obtained in
response to NaCl 50 mg L-1 + spermidine 2 mM. The effects of NaCl 50 mg L-1 + putrescine 2 mM caused the highest root dry weight (1.42 g). The highest carotenoid content in petals (0.69 mg g-1 FW) and leaf chlorophyll content (14.54 mg g-1 FW) were obtained in response to KCl 50 mg L-1 + spermidine 2 mM. Also, the highest superoxide dismutase enzyme activity (85.90 unit of enzyme g-1 FW) and proline (8.4 mg g-1 FW) were obtained in response to NaCl 50 and 100 mg L-1, respectively. In summary, this research showed that polyamine foliar application, especially spermine, most significantly increased the growth indices and physiological traits in pot marigold under salinity stress.
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