PLANT PHENOLS AND POLYPHENOLOXIDASE IN NICOTIANA TABACUM DURING GREENHOUSE GROWTH, FIELD GROWTH AND AIR-CURING

A difference was noted between greenhouse Nicotiniana tabacum plants and field plants in the amounts of total soluble phenols, chlorogenic acids and rutin distributed among the leaves from upper, middle and lower stalk positions after flowering. Field plants contained more soluble phenols in upper leaves; greenhouse plants contained more in lower leaves. Total soluble phenols did not decrease during air-curing, but chlorogenic acids and rutin decreased with time during curing-chamber (primed leaves) and conventional (leaves on stalks) air-curing. Polyphenoloxidase (PPO) activity increased as plants matured. PPO activity showed an additional transient rise during the first 7-9 days of air-curing. Thereafter, the enzyme activity decreased for 3-4 weeks, reaching very low levels. Leaves from greenhouse plants contained lesser amounts of total soluble phenols, chlorogenic acids, rutin and PPO activity than field plants of the same variety during growth and air-curing. These differences between greenhouse and field plants may be related to the light transmission characteristics of glass in the wavelength region 290-330 nm. © 1969.