Analysis of Nonstructural Carbohydrates in Redroot Pigweed (Amaranthus retroflexus) and Robust Foxtail (Setaria viridisvar.robusta) Throughout the Growing Season

Abstract

Redroot pigweed (Amaranthus retroflexusL.) and robust foxtail [Setaria viridis(L.) Beauv. var.robusta-albaSchreiber orSetaria viridisvar.robusta-purpureaSchreiber] were investigated to measure the accumulation of nonstructural carbohydrates throughout two separate growing seasons. Pigweed tended to accumulate more total nonstructural carbohydrates (TNC) than foxtail, particularly in the roots. In both weeds, peak levels of TNC in leaves, stems, and roots occurred during early flowering. The primary nonstructural carbohydrate in the leaves of both weeds was starch. Reducing sugars were the predominant nonstructural carbohydrate in the stems. Starch accumulated more in the leaves of the upper third of the plant and reducing sugars occurred in the greatest quantity in the middle strata of the stem. Accumulation levels of TNC in the plant organs suggested that the stem was a major sink during the vegetative growth phases of both pigweed and foxtail.