Determination of salt tolerance levels of some avocado species

In this study conducted to determine the salt tolerance levels of some avocado seedlings, seedlings of Duke, Mexicola and Topa Topa varieties of Mexican race were used. In the study, plants were subjected to 0 (control), 50 mM and 75 mM NaCl applications. Morphological parameters such as shoot growth, stem diameter development, leaf number, leaf burning and chlorosis status and leaf chlorophyll amount (SPAD), Photosystem II (PSII), photosynthesis rate (A), Transpiration rate (E), Stomal conductance (gsw), water use efficiency (WUE), and leaf nutrient elements (Na+, K+, Ca+2, Cl-) were investigated. It was observed that increasing salt concentration caused a decrease in plant shoot length and stem diameter, leaf burning, necrosis and severe leaf shedding and leaf losses. Except for the control application, photosynthesis rate, stomal conductance, transpiration rate and water use efficiency measurements could not be made because of the advanced leaf scorch and necrosis in the plants applied with 50 mM and 75 mM NaCl. In addition, a decrease in leaf chlorophyll amount and PSII activation was detected. Na+ and Cl- concentrations increased in the leaves of all rootstocks with increasing salinity. The highest leaf Ca+2 concentration was found in Topa Topa rootstock in 75 mM NaCl application. The highest leaf K+ concentration was found in Mexicola rootstock in 75 mM NaCl application. K/Na and Ca/Na ratios decreased with increasing salinity and the highest K/Na and Ca/Na ratios were found in Topa Topa rootstock. No difference was found in K/Na and Ca/Na ratios between Duke and Mexicola rootstocks.