Shade Avoidance As a Mechanism of Crop Yield Loss Due to Weeds.

Shade avoidance syndrome is a well described plant response to impending competition, but it has been less studied in crop-weed interactions. Shade avoidance is a term given to phytochrome-mediated plant responses to light from neighboring plants that typically involves internode elongation and reduced branching and flowering. Previous research has shown shade avoidance to be a potential mechanism of crop yield loss due to weeds in crops that produce seed as the primary economic output (e.g. corn and soybean). Over the last several years, we have studied the contribution of shade avoidance to potential yield losses in the biennial root crop sugarbeet (Beta vulgaris). In the absence of direct resource competition, sugarbeet yield can be reduced by the presence of neighboring vegetation. Results of this work will be summarized.