The present work is emphasised with the herbicidal tolerance of Azolla pinnata R.Br. and its modulation with TiO2 nano-particle. Both carbohydrate and nitrogen metabolism were effected with 2,4-D as herbicide and in few cases TiO2-NP had recovered few detrimental effects. From the nutrient status in Azolla it recorded the recovery of nitrogen as well as potassium by TiO2-NP but not in case of phosphorus. However, a conversion of nitrate to ammonium was more induced by TiO2-NP under herbicidal toxicity. Similar results were obtained for inter-conversion of amino acid-nitrate pool, but no changes with glutamine synthase activity with TiO2-NP. Initially, the effects of 2,4-D was monitored with changes of chlorophyll content but had not been recovered with nanoparticle. Photosynthetic reserves expressed as both total and reducing sugar were insensitive to TiO2-NP interference but activity of soluble and wall bound invertase was in reverse trend as compared to control. The 2,4-D mediated changes of redox and its oxidative stress was ameliorated in plants with over expressed ADH activity. As a whole the Azolla bio system with TiO2 supplementation may be useful in sustenance against 2,4-D toxicity through recovery of nitrogen metabolism. Thus, Azolla-TiO2-NP bio system would be realised to monitor the herbicidal toxicity in soil and its possible bioremediation.
Keywords: Aquatic fern; Carbohydrate metabolism; Herbicide; Nitrogen metabolism; TiO2 nano-particle.