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Aristotle University Of Thessaloniki (AUTH) (2010)

Study of the influence of salinity in citrus plants

Τσαμπαρδούκας, Βασίλειος

Titre : Study of the influence of salinity in citrus plants

Μελέτη της επίδρασης της αλατότητας στα εσπεριδοειδή

Auteur : Τσαμπαρδούκας, Βασίλειος

Université de soutenance : Aristotle University Of Thessaloniki (AUTH)

Grade : Doctor of Philosophy (PhD) 2010

Résumé
Six experiments were carried out in order to study the effect of salinity on various physiological and agronomical parameters of citrus plants. The comparison between two Citrus rootstocks, the Sour orange (Citrus aurantium) and the hybrid Swingle Citrumelo (C. paradisii x P. Trifoliata), showed that the rootstocks use different salinity tolerance mechanisms. Sour orange plants accumulated greater concentrations of Na+ and Cl- in leaves compared with those of Citrumelo which restricted the transport of the toxic ions in the leaves by achieving higher concentrations in roots. Sour orange was also able to maintain the net photosynthesis despite the presence of Cl- ions, an ability which disappeared when the synergistic influence of Na+ and Cl- was established. As far as the toxicity of the two salts in concern, NaCl appeared to be more toxic than KCl. During the study of the influence of NaCl in three lemon (Citrus limon) cultivars (Navel, Lisbon, Maglini), Navel seemed to be more tolerant in comparison with Maglini. Taking into account the % dry weight as an indicator of salt tolerance, the three cultivars are ranked from the most to the least tolerant like this : Navel>Lisbon>Maglini. In the 3rd , 4th and 5th experiment, the influence of polyamines was studied. Under high NaCl polyamines enhanced the Citrus seeds germination and growth, enhanced plantlets root and shoot fresh weight , induced and enhanced rooting in microshoots and therefore the growth under saline and non saline conditions, protected the membranes from the oxidative stress, maintained the activity of peroxidases and diamine oxidases and enhanced the concentration of chlorophyll and proline in some occasions. In the 6th experiment, the data showed that salicylic acid (SA) protected from oxidative damage due to high salinity the membranes and as a result reduced the concentration of malondialdehyde (MDA), maintained the chlorophyll concentration, the Fm/Fv ratio, the internal concentration of CO2, when it was applied in concentrations less than 0.3mM for 48h. Salinity negatively affected the photosynthetic rate and the Fm/Fv ratio as an indicator of the ability of PSII to operate efficiently, the concentration of chlorophyll and the stomatal conductance which affected the internal CO2 concentration and the evaporation rate. Under high NaCl carbohydrate concentration was reduced in all experiments, whereas proline remained in the same levels, except in some occasions where it was reduced. Peroxidase activity (GuPODs) was increased and that was the case for the concentration of malondialdehyde (MDA). Because the total concentration of nutrients per plant is an indicator of the ability of the absorption of the nutrient by the plant, our data resulted that probably NaCl influenced negatively the absorption of macronutrients K,Ca and Mg and micronutrients Fe, Mn and Zn, leading to reduced total uptake per plant.

Mots clés : Citrus, Αλατότητα, Εσπεριδοειδή, Πολυαμίνες, Σαλικυλικό οξύ (SA), KNO3, NaCl, Polyamines, Salicylic acid (SA), Salinity

Présentation (National Archive of PhD)

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Page publiée le 1er juillet 2013, mise à jour le 13 mars 2020