Light Intensity: the Role Player in Cucumber Response to Cold Stress

Abstract

Low temperatures are an important limitation for geographic distributions of warm-season crops like cucumber (Cucumis sativus L.). Tolerance to low temperatures varies among different plant species and genotypes when changes in normal environmental cues occur. To cope with low temperature, biochemical and biophysical events should be coordinated to form a physiological response. We examined how light intensity influences the effects of low temperature on photosynthesis machinery and some biochemical traits. We used chlorophyll fluorescence imaging and polyphasic fluorescence transient (OJIP) to analyze cold stress (4 ºC) damage to photosynthetic electron transport chain (ETC) under different Photosynthetic Photon Flux Densities (PPFDs; 0, 300 and 600 μmol m-2 s-1), in four accessions of cucumber. The results showed that, the negative effects of cold stress are PPFD-dependent. The adverse effect of cold stress on ETC was more pronounced in plants exposed to 600 μmol m-2 s-1 compared to the control and dark-exposed plants; indicated by disturbance in ETC and higher energy dissipation. Moreover, biochemical traits including H2O2 content, ascorbate peroxidase activity and electrolyte leakage, and water-soluble carbohydrate was increased under low temperature by increase in PPFD, while chlorophyll and carotenoid contents decreased under low temperature by PPFD elevation. Low temperature induced H2O2 accumulation via suppressing APX activity in a PPFD-dependent manner. In conclusion, high PPFDs exacerbate the adverse effects of low temperature on the cucumber seedlings.

Light regulation of quality and growth of basil

“…The combination of low temperature and high light can increase chilling injury. Increased light intensity (up to 600 µmol m -2 s -1 ) in cucumber kept at 4 °C for 15 hours increased chilling injury (Ashrostaghi et al, 2022). This indicates that even short durations of low temperature can result in unwanted increase in chilling injury.…”

“…The use of postharvest light in the non-tolerant species basil has yet to be studied. The combination of high light and low temperature has a negative effect on chilling tolerance (Ashrostaghi et al, 2022). However, it remains to be studied if low light and low temperature can have a positive effect of chilling tolerance.…”