The increase in survival of winter cereal seedlings due to light exposure during ice encasement

Abstract

Exposure of cold-hardened seedlings of a range of winter cereals (11 winter wheats, 1 winter barley, and 1 winter rye) to a light intensity of 100 μE∙m−2∙s−1 during ice encasement at −1 °C markedly increased survival in comparison with that in dark ice encasement. Cold hardiness of 'Dover' winter barley and 'Fredrick' and 'Norstar' winter wheats was significantly greater after a short period of light ice encasement than dark ice encasement. Less ethanol and more CO2 accumulated in plant crowns in light than dark ice, and lactic acid accumulated in the early days of ice encasement but was little influenced by light. There was greater utilization of total nonstructural carbohydrate in the crown in dark, than in light, and greater utilization of total nonstructural carbohydrate in ice than in air at −1 °C. Considerably less oxygen was consumed by plants in light than in dark ice, while leaves in aqueous solutions at −1 °C evolved significant levels of O2 in light but consumed O2 in the dark. It is proposed that the changes in metabolic components in light are associated with low-temperature photosynthesis, which provides cellular oxygen and greater levels of energy in support of cell maintenance in plants during ice encasement.