Abstract

In an experiment with Azolla pinnata R.Br. under varying concentrations of herbicide (2,4-D), it reveals that the fern species has an wider ranges of physiological activities in moderation. Initially, the effects of the herbicide were reflected with minimum changes in dry matter accumulation in a dose dependent manner. The changes of membrane permeability had the maximum effects on 1000 μM of 2,4-D following the concentration gradient. However, the intermediate concentration of herbicide had not brought any significant changes in electrolytic conductivity. At initial concentration of herbicide treatments the electrolyte conductivity remains more stable. In support to osmotic stability plants recorded a significant change in water deficits that was experienced by proline accumulation in tissues. Thus, a steady increase in proline concentration was the feature of this species when interacts with 2,4-D. In another way the fern species had tolerated the loss of turgidity with significant accumulation of glycine-betaine with their maximum value at 1000 μM of 2,4-D. In further progress of effects of 2,4-D the plants were significantly characterised with an increase in ROS activities. Thus, ROS induced tissue lysis was detected by in vivo Evan's Blue staining of the root tissues with maximum intensity at 1000 μM of 2,4-D. The initial defence barrier of this species against ROS at cellular spaces was studied with in-gel analysis of enzyme like wallbound peroxidase. Plants registered a maximum peroxidase activities at influence of 2,4-D with 1000 μM. In addition to gene expression in Azolla a distinct polymorphism was observed as a function of 2,4-D treatments and that may be set as a bio indicator to herbicide interaction.

Keywords: Azolla, 2,4-D, Proline, Glycine-betaine, Evan's blue, Wall bound peroxidase