PHYSIO-BIOCHEMICAL AND NUTRITIONAL RESPONSES OF ABELMOSCHUS ESCULENTUS (L.) MOENCH (OKRA) UNDER MERCURY CONTAMINATION

The objective of this study was to evaluate the impact of HgCl2 (0.05, 0.10, 0.50, 1 and 2 mM) on growth, pigment, biochemical attributes, nitrogen and phosphorous contents in Abelmoschus esculentus. The shoot and root length decreased by 36.12 and 36.26 percent respectively after post-flowering stage under 2 mM HgCl2 application. Chl. a showed a maximum decrease of 63.90 percent at flowering stage when 2 mM HgCl2 were applied to the experimental plants. Chl. b, total chl. and carotenoids also showed a significant decrease with an increase in the HgCl2 concentration. HgCl2 with 2 mM showed a maximum decrease of 83.52 and 20.60 percent in protein and sugar content respectively. The plants exposed to 2 mM HgCl2 also showed an increase in the proline content (35.95%) during post-flowering stage. NR activity decreased during pre- as well as post-flowering stages at all stress levels. The nitrate, nitrogen and phosphorous values also decreased with an increase in the HgCl2 concentration during all growth stages. The accumulation of Hg in roots was synergistic with increase in the concentration of Hg throughout the stages of growth. The maximum accumulation of 41.4 percent was observed at flowering stage under 2 mM HgCl2 application.