A laboratory experiment was conducted at the Department of Field Crops laboratory at the College of Agriculture, University of Tikrit, to evaluate the allelopathic influence of the aqueous extracts from some weed species on the germination and early growth of fenugreek and its companion weeds that growth with it in fields. The trial was conducted following a Completely Randomized Design (CRD) utilizing independent contrasts, and the study consisted of 12 experimental units so each containing 10 seeds per tested species namely Sonchus oleraceus‎. (annual sowthistle), Eruca sativa (arugula, garden rocket), and Trigonella foenum-graecum (fenugreek). These seeds were treated individually one by one with various aqueous extracts such as Eucalyptus extract, Silybum marianum (milk thistle) extract and arugula extract and a distilled water for control treatment. Phenotypic traits evaluated encompassed the germination percentage of weed seeds and plumule along with radicle lengths as well as the dry weight of both plumule and radicle for both fenugreek and the associated weeds.

The results appear that the Eucalyptus extract exerted a significant inhibitory effect on Sonchus oleraceus‎ seeds, considerably a reduce of the germination percentage also plumule length and radicle length, with mean values recording 10%, 2.833 cm, and 1.667 cm, respectively. Similarly, when Eruca sativa seeds were treated with Eucalyptus extract. the lowest mean values for germination percentage, plumule length, and radicle length were observed, yielding 43.30%, 3.533 cm, and 2.133 cm, respectively. Conversely, regarding the germination and seedling growth of Trigonella foenum-graecum, the Silybum marianum extract revealed a positive stimulatory effect achieving the highest means at 96.67%, 9.033 cm and 7.377 cm respectively. concerning the dry weight of the plumule and radicle for the fenugreek plant, the Silybum marianum extract treatment recorded the maximum mean values, reaching 0.0900 g and 0.03533 g respectively.

Regarding the dry weight of the weeds, the Eucalyptus extract significantly suppressed biomass accumulation, recording the lowest dry weight means for Sonchus oleraceus‎.at 0.003667 g and for Eruca sativa at 0.01467 g.