Department of Botany, Sri Venkateswara University, Tirupati, 517502, Andhra Pradesh, India
*Present address: Department of Plant & Soil Biology, University of California, 108, Hilgard Hall, Berkeley, CA, 94720 USA.
Five nonsucculent semi-arid scrub species, Carissa spinarum, Maba buxifolia, Flocourtia sepiaria, Gymnosporia emorginata and Dodonaea viscosa exhibited scotoactive stomatal opening, nocturnal carbon assimilation and dark acidification while day time CO, uptake was predominant in Chomelia asiatiea. Foliar application of 100 mg 1−1 paraquat (1, 1’-dimethiyl-4, 4’-bipyridinium ion) completely inhibited the dark uptake of CO2. Phosphoenolypyruvate (PEP) carboxylase activity was suppressed in the treated plants while Ribulose bisphosphate (RuBP) carboxylase was relatively unaffected. The results indicated that the process of dark CO2 uptake was sensitive to paraquat.
