*3.3. Antimetabolite Assay on E. coli*

Clearing zones were produced around the inoculation spot of some strains, while the growth of most of the strains was mixed with the growth of *E. coli,* i.e., mutualistic strains. The clearing zones indicated the killing of *E. coli,* which occurred with nineteen strains. The diameter of these clearing or halo zones indicated the level of inhibition of growth of *E. coli* (Figure 3). Strain 7O0 produced the maximum diameter of the halo zone, which was followed by strains W9, O010, T42, W28, T12, T23, and L9. The average diameter of zones produced by these strains was measured to be 1.3 ± 0.08, 1.23 ± 0.13, 1.21 ± 0.08, 1.01 ± 0.10, 0.96 ± 0.09, 0.88 ± 0.06, 0.82 ± 0.06, and 0.72 ± 0.07 cm, respectively. The remaining strains showed positive interaction with the growth of *E. coli.*

#### *3.4. Antimetabolite Assay on Lettuce Seedlings*

Results indicated that the strains imparted mixed effects on the growth of lettuce seedlings (Table 2). Five of the application strains significantly reduced the dry matter, root length, and shoot length of lettuce seedlings from 18.8 to 38.9%, 19.7 to 36.3%, and 17.3 to 24.3%, respectively. These strains were T18, T12, W9, W28, and O010. The strains L6 and T31 caused a significant reduction in root length only. However, the strain T38 caused a significant reduction in the length of root and shoot. There were

seven strains, which increased the dry matter, root length, and shoot length of lettuce seedlings from 15.7 to 41.5%, 16.7 to 61.4%, and 26.2 to 43.4%, respectively. These strains were T23, T42, T19, 2O0, T24, L9, and 7O0. The strains B11 and ESO-8 increased the shoot length only. The other strains remained ineffective on the growth of seedlings of lettuce.

**Table 2.** The effect of cyanogenic *E. coli* inhibiting rhizobacteria on lettuce seedlings in agar bioassay. Values sharing the same letter(s) in a column do not differ significantly from each other at *p* < 0.05. Values in a column indicate mean ± standard error.


#### *3.5. Antimetabolite Assay on Broad-Leaved Dock*

The effects of the applied strains on the growth of the seedling of the broad-leaved dock were mixed, i.e., inhibiting, promoting, and neutral (Table 3). The dry matter, root length, and germination rate of the broad-leaved dock were significantly reduced by eight of the applied strains from 23.1 to 68.1%, 23.9 to 61.8%, and 26.7 to 64.4% than control, respectively. These strains were T42, O010, L9, T38, 7O0, ESO-11, W9, and W28. The strain T19 caused a reduction in root length and germination rate only. The strain T31 caused a significant increase in root length and germination rate of the dock. The other strains remained ineffective on the growth of the seedlings of the dock.

#### *3.6. Antimetabolite Assay on Wild Oat*

Seven strains significantly reduced the dry matter, root length, and germination rate of wild oat from 38.5 to 80.2%, 19.4 to 60.2%, and 25.4 to 70.9%, respectively (Table 3). These strains were 2O0, ESO-8, O010, T42, W28, W9, and 7O0. The strains T18, T12, ESO-11, and T75 significantly inhibited the germination rate from 14.5 to 25.4% but no other parameters. The strain T24 only reduced the root length of wild oat. The root length and germination rate of the weed were significantly increased by strain T19 up to 13.3 and 14.5%, respectively. The other strains remained ineffective on the growth of the seedlings of wild oat.

#### *3.7. Antimetabolite Assay on Little Seed Canary Grass*

Eight of the nineteen applied strains caused a significant reduction in dry matter, root length, and germination rate of little seed canary grass from 16.5 to 69.4%, 24.2 to 63.6%, and 20 to 52.7%, respectively (Table 4). These eight strains were T75, 7O0, T42, ESO-11, O010, W9, L9, and W28. The strains T18 and T12 reduced only the root length (10.5–20%) and germination rate (18.2–25.4%). The strain 2O0 significantly reduced the dry matter (21.2%) and root length (10.8%) of the weed. However, the strain T19 significantly increased the dry matter (23.5%) and root length (10.4%) of the weed. Other strains remained ineffective on the growth of the seedlings of this weed. The pictorial view of the assay is available in (Figure 4).

**Table 3.** The effect of presumed allelopathic bacteria on the germination and seedling growth of broad-leaved dock and wild oat in agar bioassay. Values sharing the same letter(s) in a column do not differ significantly from each other at *p* < 0.05. Values in a column indicate mean ± standard error.


**Table 4.** The effect of presumed allelopathic bacteria on the germination and seedling growth of little seed canary grass and common lambs' quarter. Values sharing the same letter(s) in a column do not differ significantly from each other at *p* < 0.05. Values in a column indicate mean ± standard error.


**Figure 4.** The pictorial view of seedlings of little seed canary grass growing on water agar in agar bioassay.
