The impact of foliar fertilizers on growth and biochemical responses of Thymus vulgaris to salinity stress |
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Authors: | Ahlem Zrig Jorge F. S. Ferreira Foued Hamouda Taieb Tounekti Samy Selim Soad Al Jaouni |
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Affiliation: | 1. Research Unit of Biodiversity and Valorization of Bioresources in Arid Zones, Faculty of Sciences of Gabès- City Erriadh, Gabes, Tunisia;2. US Salinity Laboratory (USDA-ARS), Riverside, CA, USA;3. Research Unit in Enterprise and Decisions, Higher Institute of Management, Gabes, Tunisia;4. Centre for Environmental Research and Studies (CERS), Jazan University, Jazan, Kingdom of Saudi Arabia;5. Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, Jouf University, Sakaka, Saudi Arabia;6. Microbiology and Botany Department, Faculty of Science, Suez Canal University, Ismailia, Egypt;7. Department of Hematology and Youssef Abdulatif Jameel Chair of Prophetic Medicine Application (YAJCPMA), Faculty of Medicine, King Abdulaziz University, Jeddah, Kingdom of Saudi Arabia |
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Abstract: | Salinity reduces plant biomass and may lead to death when severe. To cope with the negative effects of this stress, plant species present specific physiological or biochemical responses. In this work, we hypothesized that spraying salt-stressed thyme leaves with K+ and Ca2+ could mitigate the negative effects of salinity on plant growth and metabolism. To test this hypothesis, we grew thyme plants under salinity stress for two and four weeks before applying foliar sprays. Also, to test the effect of stress relief, treated plants were allowed two weeks of recovery after four weeks of salt stress. In general, after two and four weeks of salinity stress, the leaf fresh weight of thyme plants was reduced by 31 and 43%, respectively. Salinity also decreased the relative water content, water, and osmotic potentials and led to ion imbalances and nutrient deficiencies. Salinity altered concentration of some essential oils, but leaf antioxidant contents remained fairly stable, except for a significant increase for plants under NaCl?+?KCl two weeks after treatment. Our results indicated that stressed plants accumulated significantly more soluble sugars and amino acids in comparison with the control. Foliar sprays with KCl and CaCl2 reversed the negative effects of salinity on plant biomass and induced the accumulations of compatible solutes. Moreover, concentrations of some essential oils and gallic acid increased in sprayed plants, but these effects were dependent on the type and duration of the treatment. Overall, spraying leaves with K+ and Ca2+ was able to mitigate salinity stress in Thymus vulgaris even during the recovery period. |
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Keywords: | Amino acid antioxidant activity carbohydrate essential oils osmotic adjustment Thyme |
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