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Title: THE BIOLOGY AND WATER USE OF KEY SUMMER ANNUAL WEEDS IN COLORADO CROPS

Author
item HELM, A - COLO STATE UNIV EXTENSION
item WESTRA, P - COLO STATE UNIV FACULTY
item Henry, William

Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 1/2/2004
Publication Date: 1/2/2004
Citation: Helm, A., Westra, P., Henry, W.B. 2004. The biology and water use of key summer annual weeds in colorado crops. [Agronomy Abstracts]. Presented at the Western Society of Weed Science Annual Meeting. March 2004. Colorado Springs, Colo.

Interpretive Summary:

Technical Abstract: On May 21, 2003 eight (8) weed species were planted in the integrated vegetation management greenhouse at Colorado State University. The 8 species were Amaranthus retroflexus, Chenopodium spp., Kochia scoparia, Salsola iberica, Panicum miliaceum , Echinochloa crus-galli, Setaria virdis, and Chenchrus longispinus. These species were planted in 3 different sized pots (10454cm3, 1303cm3, and 207cm3) with 4 replications. These pots were maintained at field capacity to determine total biomass production in a given soil volume. All species and replications were harvested on August 22, 2003. Measurements taken were leaf area index (LAI), height to node ratio for broad leaf plants, Tillers per centimeter, biomass production and percent moisture. LAI was measured using reflected light technique. Among the broadleaf weeds Amaranthus retroflexus showed the highest LAI and height to node ratio in the large pots with 2277 cm2 LAI and 3.73 cm per node. Within the grass weeds Panicum miliaceum provided the greatest LAI with 2361 cm2. Echinochloa crus-galli provided the highest number of tillers per cm of height with 55.88 cm per tiller. Salsola iberica provided the greatest biomass production among all weed species. Percent moisture for all weed species averaged between 75 and 85 percent. These preliminary data indicate of what these weed species are capable of producing under optimum conditions. Future research will be initiated to determine biomass production during development into different growth stages (establishment, inflorescence, and seed production).