Wounding of root or basal stalk prior to harvest affects pre-harvest antioxidant accumulation and tobacco-specific nitrosamine formation during air curing of burley tobacco (Nicotiana tabacum L.)

Wounding stresses were tested for their ability to induce an accumulation of antioxidants in harvested tobacco (Nicotiana tabacum L.) and for the reduction of tobacco-specific nitrosamines (TSNA) during subsequent air curing. Data indicated that root pruning of burley tobacco 1 week before harvest resulted in an increased accumulation of alpha-tocopherol, chlorogenic acid and rutin, compared with untreated plants. Wounding also increased total antioxidant capacity in both green and cured tobacco. Field experiments performed over 3 years showed a consistent decrease in nitrite concentration in leaves from wounded tobacco, and the reduction in TSNA was always associated with reduced levels of nitrite. Depending on climate and curing conditions, curing resulted in significant reductions in TSNA, compared with unwounded, control plants. Thus, the results suggested that higher endogenous antioxidants present during senescence and curing of wounding-stressed tobacco may affect the propensities of those tissues to inhibit TSNA formation by reaction with nitrite.