CHLOROPHYLL FLUORESCENCE AND MINERAL NUTRITION IN CITRUS LEAVES UNDER SALINITY STRESS

In vivo measurements of chlorophyll fluorescence (Fv/Fm) were used to evaluate the physiological effects of salt stress on two citrus rootstocks (Alemow and Cleopatra mandarin), with and without reciprocal grafts, grown in a nutrient solution with different sodium chloride (NaCl) levels: 0, 25, or 50 mM NaCl(T0, T1, and T2, respectively). Values of chlorophyll fluorescence, measured with non-destructive and non-invasive techniques for periodic sampling or screening, were correlated linearly with the corresponding concentrations of magnesium in both rootstocks and their grafted combinations. Chlorophyll fluorescence was also correlated with leaf potassium (K) in. Cleopatra mandarin in its grafted combination, with leaf phosphorus (P) in Cleopatra mandarin grafted on Alemow and with leaf nitrogen in Cleopatra mandarin. We did not find differences between different saline levels T1 and T2 or between T1 and the control. In Alemow rootstock, the chlorophyll fluorescence differed according to whether it was used alone or in combination, and it also differed from Cleopatra mandarin.