Throughout their lives plants are constantly exposed to abiotic stress. Lead is a highly toxic element and has not yet been shown to have a positive effect on plants. This element causes inhibition of physiological and biochemical processes in plants. Exogenous application of vitamins to plants has been successfully used to minimize the adverse effects of abiotic stresses on plant growth, biochemical and physiological processes. The objective of the present study was to examine whether the adverse effects of 0.5 – 2.0 mM lead nitrate stress on plants could be mitigated by exogenous application of 25 – 100 µM nicotinamide (vitaminum PP). The study material consisted untreated seeds of spring barley (Hordeum vulgare var. Eunova). The tolerance to Pb stress was evaluated by measuring morphological traits (root and shoot length, plant fresh weight), biochemical and physiological parameters (malondialdehyde and proline content, catalase activity, total chlorophyll and carotenoids content) of 10-day-old seedlings originated from embryos cultured on the MS which contained lead and exposed to nitrate stress alone or with nicotinamide. All results, when compared to the control, showed that the higher concentration (2.0 mM) of Pb(NO3)2 had the most remarkable effect on the measured parameters. The reduction of tested parameters in barley seedlings is indicated. The addition of nicotinamide to the MS medium alleviated the adverse effect of Pb(NO3)2 stress on plant growth and selected biochemical parameters – MDA (malondialdehyd) and proline contents and CAT (catalase activity). Nicotinamide at 50 and 100 μM gives the best effect.  

24.1.2019