The effects of different nickel concentrations on some morpho-physiological characteristics of parsley (Petroselinum crispum)

Nickel as a heavy metal is considered a fatal and toxic element for humans, animals and plants. However, some plants are known as hyper accumulator for nickel and sometimes seem to be useful for plant growth. Thus, investigation on the effect of nickel on plant's growth is an issue of importance. In this paper, we have studied the effect of different nickel concentrations on parsley growth and morph-physiological characteristics and its effect on absorption of some macro elements in this plant. Seeds of parsley were germinated in germinator and seedlings were transferred to hydroponics culture. The seedlings were grown in Hogland solution with different nickel concentrations (in form of nickel nitrate) of: 0, 0.25, 0.5, 0.75, 1, 1.5, 2 and 4 ppm. A completely randomized design with 8 treatments and 7 replications per treatment was used. Twelve weeks after treatments, morph-physiological characteristics including SPAD number, plant biomass, length of shoot and root, leaf area, leaf number and stomatal resistance were measured. The amount of absorbed nickel in plant foliages and roots of different treatments were also measured. The results revealed that the application of different nickel concentrations were decreased SPAD number, plant biomass, leaf area and leaf number, but the stomatal resistance were increased. Increase of nickel concentration resulted increasing Ni concentrations of plant foliages and roots. Nickel with 0.75 ppm concentration or higher imposed a toxic effect on parsley as general wilting and significant reduction in most morph-physiological characteristics.