Selenium Priming Selectively Ameliorates Weed – Induced Phytotoxicity by Modulating Antioxidant Defense Components in Lentil (Lens culinaris Medik.) and Grass Pea (Lathyrus sativus L.)

Aims: Present investigation was performed to assess the phytotoxic effect of weed, Ageratum conyzoides L. on two pulses, lentil (Lens culinaris Medik.) and grass pea (Lathyrus sativus L.) and the ameliorative role of selenium (Se) to counter it.
Place and Duration of Study: Leaf samples of Ageratum were collected from the lentil-growing fields of Kalyani, West Bengal, India during winter of 2011-12. The lab-based works were performed at Department of Botany, R.P.M. College, West Bengal, India throughout the period of 2012.
Study Design: The study was carried out using four replicates treatment-1 in a completely randomized block design.
Methodology: Ageratum leaf aqueous extract of 200 mg ml-1 (w/v) was prepared and used on the two crops in (a) nutrient media, and (b) media + Se concentrations of 10, 20 and 40 µM separately. Also, Se was added alone (no extract) in nutrient media. A control (no exogenous Se, no extract) was maintained. The experiment was performed in an environmentally controlled growing chamber and plants were grown till flowering. Different morpho-physiological parameters along with root-tip mitosis and flower bud meiosis were studied at appropriate stages with standard methodology and analysed statistically.
Results: Leaf extract induced phytotoxicity through significant perturbation in ascorbate and glutathione redox and activities of SOD, APX, DHAR, GR, CAT and GPX, resulting in over-accumulation of H2O2 and lipid peroxidation product as the obvious marking of oxidative damage with more severe effect on lentil. Se-priming significantly ameliorated this situation at 20 and 40 µM in grass pea and at 40 µM in lentil by modulating antioxidant defense machinery in favor of growth. Se alone at 20 µM promoted growth of both crops but exhibited toxic effect on lentil at 40 µM. Phytotoxic effect of extract was also manifested by aberrant mitotis and meiosis in both plants.
Conclusion: Ageratum leaf extract triggered oxidative stress. Se-priming at selective concentration ameliorated extract-induced phytotoxicity in lentil and grass pea by modulating anti-oxidant defense components.