Determination of salt stress tolerance of 'Hatay' clonal apple rootstock candidate (malus sylvestris L. mill. subsp. orientalis) under in vitro conditions

Salt stress is an important environmental factor that negatively affects the growth and development of plants. Among fruit species, apple is one of the most sensitive plants to salt stress. In this study, the tolerance of the 'Hatay' clonal apple rootstock candidate to salt stress under in vitro conditions was investigated. Different salt concentrations (1/4 dilute MS, 1/2 dilute MS, MS (control), MS + 1 g l-1 NaCl, MS + 2 g l-1 NaCl, MS + 4 g l-1 NaCl, MS + 6 g l-1 NaCl, MS + 8 g l-1 NaCl, MS + 10 g l-1 NaCl) were used in the study. As a result of salt stress, plant height, leaf area, stomatal conductance, plant fresh and dry weight, rooting rate, root number, root length, root fresh and dry weight were measured. According to the study results, the best plant height was obtained in the MS (control) medium, while the lowest plant height was observed in the 1/4 MS medium. The highest values for plant fresh weight and plant dry weight were found in the MS + 1 g l-1 NaCl medium, while the lowest values were detected in the 1/4 MS medium. In terms of leaf area, the highest value was obtained in MS (control) medium, while the lowest value was measured in MS + 1 g l-1 NaCl medium. Stomatal conductance was highest in the 1/2 MS medium and lowest in the MS + 1 g l-1 NaCl medium. The highest rooting rate was found in the MS + 1 g l-1 NaCl medium, while the lowest value was recorded in the 1/4 MS medium. In general, the best results in terms of root number, root length, root fresh and dry weight were obtained in the 1/2 MS medium, while the lowest results were found in the 1/4 MS medium. In the MS + 2 g l-1 NaCl, MS + 4 g l-1 NaCl, MS + 6 g l-1 NaCl, MS + 8 g l-1 NaCl and MS + 10 g l-1 NaCl media, the plantlets died. In conclusion, the 'Hatay' clonal apple rootstock candidate was found to be sensitive to salt stress. Keywords: Apple rootstock candidate, in vitro, Morphological characteristics, Salt stress, Stress