|BEGONIA, MARIA FATIMA|
Submitted to: Mississippi Academy of Sciences Proceedings
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/30/1998
Publication Date: N/A
Interpretive Summary: The current popular manner of handling weeds in crops is through the use of chemicals (herbicides) to eliminate the weeds from farmers' fields to assure profitable grain harvests. Although herbicides are generally used with care and are recommended for specific weed and soil scenarios in a field, public concerns persist regarding potential contamination of drinking water, soils, and food products by the fraction of herbicides remaining in the environment long after the weeds have been controlled. Because of this public concern about the environmental safety of herbicides, there is interest in developing nonchemical weed management schemes. This study investigated the use of microorganisms naturally found in crop fields for inhibiting the growth of weed seedlings. Since these microorganisms are active against weed seeds and seedlings in the soil, it was necessary to develop a procedure for placing them in the "seed-soil zone" to assure contact between the weed seed and the microorganism. We combined the microorganisms with a peat substance and placed them in soil using a method similar to those used for fertilizer application. This allowed the microorganisms to thrive in the soil and to attack seeds of the weed velvetleaf as they germinated. Seedling emergence was reduced by about 50% and seedling growth by about 40%. Our results suggest that properly prepared biological agents can be an effective part of an overall system for managing weeds with less reliance on herbicides. Demonstrating that selected microorganisms in a peat formulation can adequately inhibit weed growth is useful information to the biotechnology industry for use in developing nonchemical products for weed control.
Technical Abstract: Preemergence applications of rhizobacteria to soil were carried out to evaluate their effectiveness as biological agents in controlling weeds in the growth chamber, greenhouse, and field. Results indicated that various rhizobacteria isolates inhibited weed seedling growth and exhibited deleterious effects including stunted, necrotic tap roots, severely inhibited lateral root development, and chlorotic foliage. Soil inoculation studies with selected rhizobacteria resulted in reduced seedling emergence, decreased seedling vigor, and severely damaged root systems. Results also indicated that rhizobacteria can be effective biocontrol agents at the rate of 10**8-10**9 cells m**-2 in the growth chamber, greenhouse, and field whether they are used as liquid or peat-base inoculants.