Effects of Drought Stress on Physiological and Biochemical Indices in Hybrid Apple Rootstocks

This study was performed to screening of some hybrid apple rootstocks for drought stress using physiological and biochemical indices in leaf. The experiment was carried out in a CRBD design, in a factorial scheme 12×2 (12 types of apple and  2  irrigation regimes) with three replicates. The types of apple studied were 1 year old plants including genotypes AR1 to AR11 accompanied by MM111 as control (drought tolerant). Irrigation regimes applied in this study were 20 and 40 percent of FC Under drought stress, the apple rootstocks physiologically and biochemically exhibited different responses. Drought stress symptoms evaluated in this experiment were reduction of cell membrane stability, photosynthetic pigments, and chlorophyll fluorescence, increment of proline and malondialdehyde content.  In this experiment at least one of the aforementioned indicators were observed in the AR1, AR3, AR5, and AR7 being identified as sensitive rootstocks. In contrast, the rest of rootstocks with the most physiological stability and the least damage were considered drought stress tolerant and selected for subsequent studies.