IMPROVING COLD STRESS TOLERANCE IN CORYLUS AVELLANA L. USING VARIOUS CHEMICAL COMPOUNDS

Corylus avellana L., common hazelnut, is a globally cultivated economically valuable nut crop tree with a sensitivity to abiotic stresses remarkably low temperature. Its intensity varies based on the growth and developmental stage. The commercial consequences of cold stress on nut setting of hazelnuts are significant and practical approaches to address the problem are highly demanded. To tackle the issue of cold stress intolerance in C. avellana and provide producers with practical solutions, this study aimed to investigate the effects of various chemical substances on ten years old C. avellana trees under cold stress and its responses at the physiological and biochemical levels in leaves and female and male flowers. Hazelnut trees were treated with salicylic acid (3 mg L-1), potassium (2 mg L-1), thiofer (5 mg L-1), biobloom (66 mg L-1), and amino acid (0.5 mg L-1) in different treatments using the foliar spray under an average temperature of 4.13°C. It could be observed that the exogenous application of the compounds affected osmotic regulation (enhancement of protein and proline content) and antioxidant enzymes (superoxide dismutase, catalase, ascorbate peroxidase, and glutathione peroxidase). In the case of the anthocyanin and photosynthetic pigments, the content of chlorophyll a, b, and total in leaves of trees treated by potassium with 217.38 ± 6.13, 66.23 ± 6.21, 150.66 ± 4.32, and 19.01 ± 2.20 mg g-1 fresh weight, showed the highest quantities. The leaves treated by salicylic acid had the highest content of carotenoid (289.62 ± 2.41). The same pattern can almost be applied to the range of these substances in male and female flowers. Although all five used helps C. avellana plants to overcome cold stress better, salicylic acid and potassium were the most effective. It can be concluded that the widespread commercial application of these chemical compounds to confer cold resistance to hazelnut trees is highly recommended.