The effect of 6-furfurylaminopurine on senescence in tobacco-leaf tissue after harvest.

1. The concentration of chlorophyll decreased and the concentration of alpha-amino nitrogen and the absolute and specific activity of peptidase increased in disks of tobacco leaf incubated on water in darkness at 25 degrees . 2. Although 6-furfurylaminopurine (kinetin) applied to the disks inhibited the increase in activity of peptidase after 4 days, this effect was too slow to account for the significant inhibition of increase in alpha-amino nitrogen after 24hr. 3. Treating with kinetin also delayed loss of chlorophyll and soluble protein, though not until 4 and 8 days respectively. 4. The only significant effect of treating disks prepared from tobacco plants deficient in nitrogen with kinetin for 8 days was to inhibit the increase in alpha-amino nitrogen. 5. Adding kinetin (5mmum to 5mum) in vitro did not affect the activity of peptidase extracted from tobacco leaf.