Role of Light in the Development of Post-chilling Symptoms in Maize

Abstract

The effect of light (250 μmol m-2s-1) on the appearance of post-chilling symptoms was investigated in cold-treated maize (Zea mays L. hybrid Furio) seedlings using electrolyte leakage and chlorophyll fluorescence induction measurements as indicators. The longer the cold pretreatment (0.5 °C) in complete darkness, the more rapid the decrease in Fv/Fm and the increase in electrolyte leakage during cold treatment in the light. The most important difference in the changes in these two parameters is that the changes in Fv/Fm occur much earlier if the cold treatment is carried out in the light. These findings suggest that chilling stress in cold sensitive maize plants led to an increased susceptibility to photoinhibition at low temperatures. Fv/Fm and electrolyte leakage changed not only at low temperatures but also after a certain cold pretreatment period at normal temperature. When the seedlings were returned to 25 °C after various chilling periods in the dark both parameters showed that post-chilling symptoms appeared much more rapidly in the light than in the dark. By contrast to the change in Fv/Fm, where plants chilled for only two days exhibited differences in post-chilling changes in the light and dark, a substantial increase in electrolyte leakage was only observed after four days of cold pretreatment. These results suggest that photoinhibition has a role not only during the chilling period, but also in the appearance of post-chilling symptoms.