Determination of Salt Tolerance Levels of Some Avocado Species

Due to global climate change, the salinity problem is increasing day by day. Avocado (Persea americana Mill.) is one of the species most sensitive to salinity and even at low salt levels, the vegetative growth, yield and fruit quality of avocado are affected. Therefore, it is important to determine the salt tolerance levels of avocado seedlings. In the study, seedlings of Duke, Mexicola and Topa Topa varieties belonging to the Mexican race were used. In the study, morphological parameters such as shoot growth, stem diameter development, leaf number, leaf burning and chlorosis status and leaf chlorophyll amount (SPAD), Photosystem II (PSII), and leaf nutrient element (Na+, K+, Ca+2, Cl-) values were examined. In order to mimic salt stress on seedlings, NaCl was applied at concentrations of 0 mM, 50 mM and 75 mM during the experiment. At the end of the experiment, it was observed that increasing salt concentration caused a decrease in plant shoot growth and stem diameter, leaf necrosis and severe leaf losses. It was determined that there was a decrease in the amount of chlorophyll in the leaves of the plant and the activation of PSII with increasing salinity. Na+ and Cl- concentrations increased in the leaves of all rootstocks with increasing salinity. K/Na and Ca/Na ratios decreased with increasing salinity and the highest K/Na and Ca/Na ratios were found in the control group in the Topa Topa rootstock. No difference was found in terms of K/Na and Ca/Na ratios between Duke and Mexicola rootstocks.