Allelopathic Effects of Four Invasive Weed Leaf-Residues on Germination Dynamics of Wheat (Triticum aestivum L.) Crop

Abstract

Weed residues remaining in agricultural fields can influence crop establishment through allelopathic interactions, although the extent of their effects varies among weed species. The present study investigated the impact of leaf residues of four common weeds, Mesosphaerum suaveolens, Achyranthes aspera, Phalaris minor, and Chenopodium murale, on the germination dynamics of wheat (Triticum aestivum L.) under pot culture conditions. Powdered leaf residues were incorporated into soil at 1, 2, and 4 g kg⁻¹ soil, with untreated soil serving as the control. Ten seeds were sown per pot, with three replications per treatment, and germination was monitored daily until completion. Germination percentage, germination rate index, mean germination time, mean germination rate, germination index, coefficient of velocity of germination, and soil organic carbon were evaluated. The results showed significant species-specific and concentration-dependent inhibitory effects of weed residues on wheat germination. Increasing residue concentrations progressively reduced germination percentage and germination-related indices while increasing mean germination time. At the highest residue concentration (4 g kg⁻¹), germination percentage declined from 100% in the control to 80% in soils amended with Mesosphaerum suaveolens and Achyranthes aspera, 70% with Phalaris minor, and 73.3% with Chenopodium murale. In contrast, soil organic carbon increased in residue-amended soils, reaching 1.58–1.76% compared with 0.75% in the control. These findings indicate that weed leaf residues can simultaneously enhance soil organic carbon and adversely affect wheat germination, highlighting the importance of considering weed species in residue management decisions. The study contributes to a better understanding of allelopathic plant–plant interactions and provides useful information for developing sustainable weed management and crop production strategies. Future research should focus on identifying the specific allelochemicals responsible for the observed effects and validating these interactions under field conditions.