Abstract

The effect of varying hydrogel (0, 0.05 and 0.1% w/w) supply on major antioxidant enzyme (super oxide dismutase, SOD; catalase, CAT and peroxidase, POD) activity, membrane permeability and salt tolerance index (STI) of bean plants in different salt source and doses stress were investigated. Plants were treated with eight salt sources (NaCl, Na₂SO₄, CaCl₂, CaSO₄, KCl, K₂SO₄, MgCl₂, and MgSO4) and four concentrations (0, 30, 60, and 120 mM doses) for 60 days in a growth media. Salt type, doses and hydrogel (HG) affected soil electrical conductivity. Soil salinity affected the parameters considered and changed the antioxidant activity of plants. Different salt concentrations negatively affected STI of plants. High salt concentration caused substantial increase leakage of plant. CAT antioxidant enzyme activities of plants decreased with increasing salt doses, and the lowest value was obtained for NaCl application. SOD and POD enzyme activity of plant were increased with increasing salt doses, and the highest value was obtained for NaCl application. HG added to saline soil significantly improved the variables affected by high salinity and also reduced soil electricity conductivity, electrolyte leakage of plant, enhanced STI and caused decrease SOD and POD  enzyme activity. The result suggested that HG have great potential for use in alleviating salinity stress on plant growth and growth parameter, in saline soils of arid and semi-arid areas. This HG appears to be highly effective for use as soil conditioners in vegetable growing, to improve crop tolerance and growth saline conditions. It is intended to confirm the results of these studies by field trials.

Key words: Bean, salinity, enzyme activity, hydro gel.