Dactyloctenium aegyptium (L.) Willd. (Poaceae) Differentially Responds to Pre- and Post-Emergence Herbicides through Micro-Structural Alterations

Abstract

Herbicides are widely used to kill weeds and increase crop production all over the world. Nevertheless, some weeds show certain structural modifications in response to herbicide application that impart mostly partial or sometimes complete tolerance to these noxious plants. The present study was focused on morpho-anatomical modifications in the root, stem, and leaves of Dactyloctenium aegyptium (L.) Willd. treated with different herbicides and to examine whether it possesses tolerance against herbicides. Two pre- and four post-emergence herbicides were applied to D. aegyptium at the recommended dose in a randomized complete block design (RCBD). Pre-emergence herbicide Bromoxynil enhanced root growth (30%), leaves per plant (3%), and leaf fresh weight (17.2%). Increased stem epidermal thickness (100%) was the most notable feature among anatomical attributes. Post-emergence herbicides generally increased stem epidermal thickness 33–56%), leaf sheath thickness (5%), and root area in roots. Other modifications included increased sclerenchymatous thickness in the stem (133–255%), and epidermal thickness (100–200%) in the leaf blade. These characters assisted D. aegyptium to cope with herbicide toxicity. Collectively, pre-emergence herbicides more effectively controlled D. aegyptium compared with post-emergence herbicides.