THE ROLE OF POTASSIUM NITRATE IN PHYSIOLOGICAL PARAMETERS OF CITRUS AURANTIUM SEEDLINGS EXPOSED TO SALINITY

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.

VI International Symposium on Banana: XXVIII International Horticultural Congress on Science and Horticulture for People (IHC2010): International Symposium on Citrus, Bananas and other Tropical Fruits under Subtropical Conditions

Z. Kostopoulou, I. Therios, V. Tsirakoglou , A. Molassiotis

Citrus aurantium, salinity, KNO₃, proline, carbohydrates, phenols, photosynthesis, stomatal density

https://doi.org/10.17660/ActaHortic.2012.928.45