Response of Wheat Seedlings to Ni Stress: Effects of Supplemental Calcium

Abstract

The effect of excess Ni (1 mM Ni) on wheat plants as well as the role of Ca (1 mM Ni+5000 microM Ca) for amelioration of toxicity and recovery of growth and photosynthesis in Ni-stressed wheat was evaluated. Growth, nutrient status (Ca, Mg, Fe, K, Na), and photosynthesis showed a distinct decrease strictly related to the period of treatment. Calcium ameliorated to a certain extent toxic symptoms of Ni, due to antagonistic action between Ni and Ca ions. Since chlorophyll content and variable fluorescence (Fv) decreased significantly, but Fo did not particularly change, the decrease of t1/2 with increasing duration of Ni exposure indicates negative changes on the acceptor side of PSII, which also may result from diminution of Calvin cycle. The maximum quantum yield for energy trapping was also suppressed. Plant transfer to Hoagland solution+5000 microM Ca caused recovery to plant morphology and physiology. Even in control plants, during recovery period an increased Ca concentration in plant tissues with concomitant increased rates of growth and morphology was observed. Ni concentration in plants exposed to 1 mM Ni+5000 microM Ca was lower than in plants exposed to 1 mM Ni. In all treatments a certain increase of plant nutrients was observed during recovery.

Alleviation of Nickel-Induced Stress in Mungbean through Application of Gibberellic Acid

“…It is clearly evident from the work of other scientists that Ni toxicity decreases the tissue water contents, nutrient uptake, iron transport and causes mitotic inhibition (Gajewaska et al, 2006;Saito et al, 2010), which might result in decreased growth and yield of mungbean. Furthermore, reduced photosynthetic and transpiration activities (Ouzounidou et al, 2006) and decreased enzymatic and antioxidant activities (Dubey and Pandey, 2011) due to Ni stress could also be the reason of decreased growth and yield of mungbean in Ni contamination. The plants grown on contaminated soil accumulates metal contents, which result in restricted growth of plants due to alterations in normal biochemical and physiological process like protein penetration, inhibition of enzyme activity, and impaired nutrition etc.…”

Growth, root and leaf structure, and biomass allocation in Leucanthemum vulgare Lam. (Asteraceae) as influenced by heavy-metal-containing slag

“…Different metals vary greatly in their detailed biochemical effects, but they usually cause some kind of oxidative damage, resulting in phenotypic effects which often are similar for the different elements (Shaw et al 2004). For example, chlorophyll content and photosynthesis are reduced by exposure to elevated levels of Cu, Ni and other heavy metals (Burzynski and Kłobus 2004;Martins and Mourato 2006;Ouzounidou et al 2006;Gajewska et al 2006;Alam et al 2007). Heavy metals reduce the number of chloroplasts and the area of thylacoid membranes, and cause damage to root tips (Barceló and Poschenrieder 2004).…”

Occurrence, physiological responses and toxicity of nickel in plants

“…This can result in the retardation of germination, growth suppression, and reductions in yields (Madhava Rao and Sresty 2000;Seregin and Kozhevnikova 2006a, b). These inhibitory effects of Ni on the growth of plants can be reduced by supplying additional Mg (or Fe) ions (Genrich et al 1998;Gon_alves 2007;Ouzounidou et al 2006). Therefore, Ni toxicity in plants is partly due to interference with other essential metal ions.…”