The role of potassium nitrate in physiological parameters of Citrus aurantium seedlings exposed to salinity
2012
Kostopoulou, Z. | Therios, I. | Tsirakoglou, V. | Molassiotis, A.
A hydroponic experiment was carried out under control growth conditions to investigate the impact of KNO3 on the physiology of Citrus aurantium L. seedlings exposed to salinity. Treatments were: (i) Control, plants receiving nutrient solution without NaCl, (ii) Salinity treatment, as for control plus 50 mM NaCl. The salinity treatment was combined with supplementary KNO3 at three concentrations (5, 10 or 20 mM KNO3). Data indicate that the salt treatment (50 mM NaCl) led to significant decreases in photosynthetic rate, stomatal density and total chlorophyll content, accompanied by decreases in leaf K+/Na+ ratio. However, carbohydrates and proline content were unaffected in the leaves of NaCl-treated plants. Supplementary 20 mM KNO3 significantly ameliorated the adverse effects of salinity on chlorophyll content. However, exogenously applied KNO3 does not measurably affect photosynthetic rate, stomatal density, carbohydrates content and K+/Na+ ratio compared to NaCl exposure. Additionally, content of total phenols was reduced by external KNO3 applications whereas proline content was suppressed by 10 mM KNO3 application. These observations suggest that KNO3 has a negative impact on phenol biosynthesis under salinity conditions.
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