Morphological, Physiological and Molecular Responses of Four Hazelnut (Corylus avellana) Cultivars Under NaCl Salinity Stress

Hazelnuts are glycophytic and sensitive plants to salt, especially to chloride ion. However, the genotypes might be different in responses to salt stress. This search attempted to understand the behavior of four hazelnut commercial widely grown cultivars ('Segorb', 'Ronde de Piemant', 'Fertile de Coutard' and 'Negret') under salinity stress. The experimental four-year-potted plants were treated with four levels of NaCl (0, 30, 60, and 90 mM). Variations were found in the values of morphological and physiological indicators between the studied cultivars. The 'Fertile de Coutard' leaves contained the lowest accumulation of sodium (0.48%) and chloride (1.1%) of dry weight (DW)), a high potassium content (1.4% DW), the smallest decrease of Fv/Fm (15.85% at 90 mM K+/Na+ ratio (2.91% DW), the lowest decrease in the relative water content (RWC) (22.5%), the highest proline content (4 mu mol g(-1)) of fresh weight (FW), and a low amount of lipid peroxidation (0.6 mu mol g(-1) FW) compared to other cultivars. On the contrary, 'Segorb' contained the highest chloride content (1.63% DW), and recorded the greatest decrease of Fv/Fm (45.12% at 90 mM NaCl) and K+/Na+ ratio (1.45% DW). Changes in the expression rate of the studied transcription factors (TF) were observed. The drought-responsive element binding (DREB) transcript level significantly increased after 12 h in 'Fertile de Coutard', and 72 h in 'Segorb'. The APETALA2/ethylene-responsive factor (AP2/ERF) transcript abundance reached the highest level after 72 h of treatment in 'Fertile de Coutard', while it did not change in 'Segorb'. Thus, our results indicate that the 'Fertile de Coutard' has the greatest potential to resilient salinity stress among the studied cultivars.