Deuterium isotope effects in Nicotiana tabacum

The effects of increasing concentrations of heavy water (2H2O) on the growth, development, morphology, and transpiration patterns in Nicotiana tabacum L. were studied throughout the life cycle of the plant. The higher deuterium levels caused a marked reduction in size and flowering, together with extensive tissue necrosis. These observations are consistent with the literature on the effects of deuterium on plant development. The present study showed a deleterious effect of deuterium on alkaloid production, associated with heightened transpiration rates and decreased fractionation of carbon isotopes in photosynthesis. All of the observed effects are consistent with the established view of deuterium as a nonspecific chaotropic agent, whose effects are evident at every level of plant organization.