EFFECT OF ETHYLENE TREATMENT OR COLD STORAGE ON CHANGES IN THE CONTENTS OF TOTAL AND INDIVIDUAL FREE AMINO ACIDS IN COROLLAS FROM CUT 'SONIA' ROSES

There was no accumulation of total free amino acids (calculated as the sum of the individual amino acids) in corollas from cut 'Sonia' roses either treated with ethylene (12 μl/l for 24 h at 20 °C in darkness) or untreated control. In the two groups, total amino acids decreased from the reference level (100 %, Day 0) to about 60 % (Day 3), thereafter remaining almost constant. Thus ethylene treatment did not affect the contents of total amino acids in corollas. However, there was an accumulation of total free amino acids in corollas from cut roses stored at 2 °C (cold-stored flowers). In cold-stored flowers, senescence was retarded as indicated by only a slight opening of the corolla and no subsequent petal abscission.

Hence there appeared to be no direct correlation between senescence of cut roses and accumulation of total free amino acids in the corollas.

We did not find a correlation between individual or total free amino acids and protease activity in the corollas of ethylene-treated, cold-stored or control flowers from the same batch.

Of the thirteen individual free amino acids that we determined, only leucine was clearly affected by the ethylene treatment. However changes in the contents of all free amino acids, except alanine and lysine, were affected by cold storage.

We detected only one theoretically expected interconversion between two amino acids: glutamic acid to proline, that occurred in corollas from control flowers during the first 6 days of storage.