NITROGEN-METABOLISM IN HARVESTED ASPARAGUS - NO DIFFERENCE BETWEEN LIGHT AND DARK STORAGE AT 20-DEGREES-C

To extend our knowledge of nitrogen metabolism in asparagus after harv est we monitored protein, amino acid and ammonia levels and glutamine synthetase activity in tip sections (0-30 mm) of asparagus spears (Asp aragus officinalis L. cv. Limbras 10) stored for up to 48 h in continu ous light or dark at 20-degrees-C. The patterns of change in light and dark were almost identical. Total protein content increased by 20% 12 h after harvest, before declining to harvest levels by 48 h. Ammonia increased slightly by 48 h. Glutamine synthetase activity increased 10 -15% by 18 h then declined to 90% of harvest activity by 48 h. Glutami c acid and glutamine were the most abundant amino acids at harvest, ac counting for 42% of the pool. Glutamine and proline levels fell rapidl y. By 48 h most amino acids had increased substantially, with asparagi ne accounting for 28% of the pool. Glutamine levels fell steadily duri ng storage, irrespective of the regime. Our results suggest that posth arvest nitrogen metabolism in asparagus spear tips is not modulated by light.