Residue weeds

Future research. Ample research has been conducted to demonstrate the allelopathic potential of numerous weedy species, and of their associated crops. Future research should be directed to discerning how much of this potential is realized in the field under humid, warm conditions such as that found in the Southeast United States. Newman (33), in a reflective article, concludes that "—it cannot be said with confidence that allelopathy has any significance for agriculture." The evidence so far certainly substantiates his conclusion. To get a better feel for allelopathy in the field, field studies should minimally include the weed and weed residues. 

The experimental design should include a weed-free control, a weedy control, a weed free but with weed residue treatment, and at least one treatment with weeds and residue present. Various levels of weeds and weed residue could be incorporated into the study. 

Effects of Dried-Weed Residue in Soil on Dry Weight of Grain Sorghum... 

Treatment of Weed Residue in Soil Abaxial Leaf Resistance (sec/cm) Water Potential (bars) Osmoti c Potenti al (bars) Turgor Pressure (bars)... 

Relating the effects caused by specific allelochemicals to those caused by an allelopathic plant is complicated because the inhibitory substances released from a plant are often unknown, and generally several different compounds are involved. However, the actions of the weeds studied in our investigations have certain parallels to those found from pCA and FA. The allelopathic nature of Kochi a, Jerusalem artichoke, and cocklebur was established, since both aque-ous extracts and weed residues reduced sorghum growth. The data show a concentration dependency characteristic of allelopathy, and some difference in toxicity among the three weeds was observed with cockle-bur the most toxic. 

Vazquez, R.L, Stinner, B.R. and McCartney, D.A. 2003. Corn and weed residue decomposition in northeast Ohio organic and conventional dairy farms. Agriculture, Ecosystems and Environment 95(2-3) 559-565. 

Halsall, D.M., Leigh, J.H., Gollasch, S.E., Holgate, M. The role of allelopathy in legume decline in pastures. II Comparative effects of pasture, crop and weed residues on germination, nodulation and root growth. Aus J Agri Res 1995 46 189-207. 

Bhowmik PC., Doll J.D. Allelopathic effects of annual weed residues on growth and nutrient uptake of com and... 

During the washing treatment at 85 it was noted that at the third wash the weed began to swell considerably and to disintegrate. In addition, the wash liquor became appreciably viscous, making it difficult to separate from the swollen weed. The removal of the weed residue by settling and straining became noticeably easier as the temperature rose from 20 to 60 . 

The weed residue obtained from run 6 was the most difficult, and that from run 11 the easiest to handle of the residues obtained in runs 6 to 11, inclusive. 

Bhowmik PC, DoU JD (1983) Growth analysis of com and soybean response to allelopathic effects of weed residues at various temperatures and photo synthetic flux densities. J Chem Ecol 9 1263-1280... 

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