Impact of Glyphosate Herbicide and Salicylic Acid on Seed Germination, Cell Structure and Physiological Activities of Faba Bean (Vicia faba L.) Plant

Abstract

The effects of salicylic acid (SA), glyphosate (Gly) and interaction of SA + Gly on seed germination and seedling growth, leaf morphology, cell ultrastructure and physiological alterations of Vicia faba plants were evaluated. SA (50 and 100 µM) reduced root seedling growth. Exposure to 250 and 500 µM Gly with or without SA caused an inhibition in seed germination and seedling growth of V. faba plants. Chlorosis, necrosis, welting, and growth reduction of V. faba was noticed in response to Gly and SA + Gly treatments. The photosynthetic pigment (Chlorophyll a (Chl a), Chlorophyll b (Chl b) and carotenoid (Car) contents of glyphosate and SA + Gly-treated plants were declined compared to the control. Electron microscopic observations of glyphosate-treated plants revealed disorganization in the internal structure of chloroplasts. Formation of vesicles within chloroplasts was observed in glyphosate and interaction of SA + Gly-treated plants. The lamellae and stroma thylakoids of chloroplasts were degenerated. Contents of soluble proteins and total phenolic compounds were decreased in glyphosate and SA + Gly-treated plants compared to the control. Peroxidase (POX) activity significantly increased with application of SA and glyphosate as well as with the interaction of SA + Gly compared to the control. Malondialdehyde (MDA) content in glyphosate and interaction of SA + Gly-treated plants increased compared to untreated one. The obtained results indicate that the root seedling growth of V. faba is sensitive to SA and Gly, while shoot was only sensitive to Gly herbicide treatments. The vegetative growth, cell organelles and physiological functions was negatively affected by Gly. Application doses of SA appear to be did not alleviate the toxicity of Gly herbicide on V. faba.