Figure legends
Figure 1. Illustration of the grass treatment used in the field experiment from the top-view (left) and a cross-section (right), modeled after (Emily Green-Tracewicz et al., 2011) as modified by (Schambow et al., 2019). Sugar beet was planted into the center ring, and was allowed to grow using the full depth (35 cm) of the 21-liter pail. Grass roots were constrained to the top 7.5 cm and outer 9 cm of the pail, and were isolated from the sugar beet roots using plastic. Grass was clipped as needed to minimize any direct shading of the sugar beet plant in the center. For the soil treatment, the design was the same, except no grass was planted into the potting media in the outer ring. Drawing by Jessica Perry.
Figure 2. Typical sugar beet growth porgession during the growing season. Growing degree days (GDD) calculated using the parameters described in Equation 1. The 240, 480, 720, 920, and 1200 GDD correspond to approximately 15, 30, 45, 75 days after planting sugar beet. Drawing by Jessica Perry.
Figure 3. Relationship between duration of weed presence and number of sugar beet leaf angle at ~700 growing degree days (GDD; ~45 days after planting) (A and B), number of leaves at harvest (C and D), and leaf area (E and F) in a field study conducted from 2015 to 2019, Laramie WY. Black lines show the fixed effects predictions, colored lines correspond to individual years. Panels on the left (A, C, and E) included treatments in which weeds were present at sugar beet emergence until removed later in the growing season. The dotted line in figure C and E indicate a break in the linear trend in the absence of the weed-free treatment. Panels on the right (B, D, and F) included treatments in which weeds were added at various times during the season and allowed to remain until harvest. Regression equations are from the linear mixed-effects model. P-values in parenthesis are for the reduced model that did not include the season-long weed-free treatment.
Figure 4. Sugar beet shoot growth in the weed-free (left) and weedy (right) at 41 days (648 growing degree days) in the field experiment in 2016, Laramie WY.
Figure 5. Relationship between sugar beet leaf position and leaf width (A), leaf area (B), petiole length (C), leaf length (D), and petiole proportion of total leaf length (E) at harvest in a greenhouse study conducted from Nov 11, 2018, to Feb 5, 2019, Laramie WY. Leaf pair 1 indicates the oldest leaf pair. Bars and shaded area indicate 95% confidence intervals.
Figure 6. Relationship between duration of weed presence and sugar beet leaf biomass (A and B) and root biomass (C and D) in a field study conducted from 2015 to 2019, Laramie WY. Black lines show the fixed effects predictions, colored lines correspond to individual years. Panels on the left (A, C) included treatments in which weeds were present at sugar beet emergence until removed later in the growing season. The dotted line A indicates a break in the linear trend in the absence of the weed-free treatment. Panels on the right (B, D) included treatments in which weeds were added at various times during the season and allowed to remain until harvest. Regression equations are from the linear mixed-effects model. P-values in parenthesis are for the reduced model that did not include the season-long weed-free treatment.