Nickel toxicity on seed germination and growth in radish (Raphanus sativus) and its recovery using copper and boron.

ABSTRACT

Effect of various concentrations of nickel (100, 200, 500 and1000 μM) and recovery treatments of boron (50 and100 μM) and copper (15 and 75 μM) each with 200 μM and 500 μM of nickel on germination, growth, biomass, chlorophyll, carotenoids, pheophytin, amylase, protein, sugar as well as activity of catalase and peroxidase were studied in radish (Raphanus sativus cv. Early menu) seedlings. Nickel treatments caused a considerable reduction in germination percentage, growth and biomass. The different pigments were also decreased with nickel treatments. However, boron addition with nickel recovered the negative effect on pigment contents. Among biochemical estimations, amylase activity and total proteins were found to be reduced in nickel treatments. Peroxidase and catalase activity were induced other than higher total sugar with nickel treatments. The combination of nickel with boron resulted into increased protein contents. This combination also reduced the catalase and peroxidase activity. The influence of nickel with copper failed to produce significant recovery except 200 μM nickel in combination with 15 μM copper with regard to catalase and peroxidase activity. The effect of nickel on hydrolyzing enzyme amylase was observed to be inhibitory, resulting into poor germination followed by poor seedlings growth. The stress protecting enzymes peroxidase and catalase seem to be induced under the influence of nickel, and providing protection to the seedlings.The application of boron with nickel showed improved germination and growth.The level of catalase and peroxidase were found to be significantly reduced showing normal growth and biomass of seedings.