Abstract:
Glyphosate is recognized as an effective herbicide because of its ability to suppress various weeds.
However, its potential effects on seed germination and early growth of weeds are not fully
understood. The novelty of this research lies in examining seed germination and early growth
responses of weeds exposed to glyphosate, aiming to optimize glyphosate application rates in
agricultural fields while minimizing environmental impacts. This study investigated the effects of
glyphosate on the germination and early growth of two major weeds commonly found in paddy
fields, Sorghum bicolor and Sorghum sudanense. Seeds were exposed to a range of glyphosate
concentrations; 0.0 ppm (control), 0.1 ppm, 0.3 ppm, 0.5 ppm, 0.7 ppm, 0.9 ppm, 1 ppm and 2
ppm, including environmentally realistic concentrations, for eight days. Seed germination,
morphometric and morphological changes were recorded daily. In the control treatments, seed
weight increased by approximately 50 mg and 30 mg for S. bicolor and S. sudanense, respectively.
In contrast, S. sudanense exhibited a reduction in seed weight, ranging from -1.66 mg to -0.65 mg
across treatments, while S. bicolor showed a consistent increase (~10 mg) under all treatments.
The length of emerging leaves in the control set up reached up to 2.0 cm and 3.5 cm, respectively,
in S. bicolor and S. sudanense, but was restricted to 0.6 cm under glyphosate treatments for both
species. Similarly, root length reached 2 cm and 3 cm in S. bicolor and S. sudanense, respectively,
in controls, whereas the maximum recorded root length under treatments was only 0.2 cm for
both species. Statistical analyses (ANOVA) revealed significant differences (p < 0.05) between
control and treatment groups for all assessed parameters. A glyphosate concentration of 25 ppm
completely inhibited seed germination in both species. These findings improve our
understanding of glyphosate's role in weed management and highlight its potential
environmental implications.
