METABOLITE ACCUMULATION DURING ICE ENCASEMENT OF TIMOTHY GRASS (PHLEUM-PRATENSE L)

Plants are killed by prolonged ice encasement at slightly subzero temperatures and under these anoxic conditions a number of metabolites are accumulated. Timothy grass plants encased in ice at -2 degrees C can survive these conditions for many weeks and accumulate mainly CO2 and ethanol and lower levels of malate, oxalate, citrate, fumarate and pyruvate. While the accumulation of most of the metabolites increases towards the end of the encasement period the amount of malate decreases, indicating utilisation. Late in the encasement period lactate, butyrate, and traces of malonate, formate and tartarate were detected which might be of bacterial origin. The bacteria most commonly isolated from ice-encased plants is Pseudomonas fluorescens (Trevisan) which in most cases is saprophytic. AU of the above-mentioned metabolites were also detected from thaw water in the field after long duration of ice encasement, butyrate attaining the highest concentration.