Antioxidant potentials protect Vigna radiata (L.) Wilczek plants from soil cobalt stress and improve growth and pigment composition

The experiments were conducted in earthen pots lined with polythene sheet to find out the effect of different concentrations of cobalt (0, 50, 100, 150, 200 and 250 mg/kg soil) on various morphological parameters, photosynthetic pigment contents and antioxidant enzyme activities on greengram (Vigna radiata (L.) Wilczek). Plants were watered to field capacity daily. Plants were thinned to a maximum of five per pot. The data for various morphological parameters such as, root and shoot length, number of nodules, dry weight of root and shoot and photosynthetic pigments such as chlorophyll ‘a’, chlorophyll ‘b’, total chlorophyll and carotenoids content were collected on 30 days after sowing (DAS). Antioxidant enzymes like catalase, peroxidase and polyphenol oxidase activities were analysed from both control and treated plants. All the growth parameters and pigment contents increased at 50 mg/kg cobalt level in the soil, when compared with control. Further increase in cobalt level (100-250 mg/kg) in the soil had a negative impact upon all studied parameters. From these results it is clear that Antioxidant potentials acts as a protective mechanism in Vigna radiata under soil cobalt stress.