impact of methyl jasmonate on enhancing chilling tolerance of cucumber (cucumis sativus l.) seedlings

Cucumber is a warm season crop that suffers from chilling injury at temperatures below 10°C. In recent years, jasmonates have been used for reduction of chilling injuries in plants. An experiment was, therefore, conducted to test whether methyl jasmonate (MeJA) application at various concentrations (0, 0.05, 0.1 and 0.15 mM) through seed soaking or foliar spray would protect cucumber seedlings, subjected to chilling stress. Results showed that MeJA application decreased chilling index, ion leakage, malondialdehyde content and hydrogen peroxide free radical and increased growth parameters, proline contents, chlorophylls contents and antioxidant activity. Although, seed soaking method provided better protection compared to foliar spray method, the highest cold tolerance was obtained with 0.15mM MeJA application in both application methods that caused low level of chilling index (1.67), malondialdehyde content (0.11 nm g-1 FW), hydrogen peroxide free radical (0.22 nm g-1 FW) and ion leakage (32.87%). In general, it may be concluded that MeJA could be used effectively to protect cucumber seedling from damaging effects of chilling stress at the early stages of growth.