Competition of Spurred Anoda (Anoda cristata) and Velvetleaf (Abutilon theophrasti) with Cotton (Gossypium hirsutum) During Simulated Drought and Recovery

Abstract

Cotton was grown alone (one plant/pot), in intraspecific competition (two plants/pot), and in interspecific competition with spurred anoda and velvetleaf in controlled-environment chambers, subjected to water stress by withholding water, and allowed to recover before the final harvest. Minimum leaf water potential reached during the drought period ranged from −1.87 MPa in cotton grown alone to −2.63 MPa in velvetleaf grown in intraspecific competition. Water stress reduced plant height, total dry weight, and leaf area in all species, compared to well-watered controls. Reductions in cotton growth due to intra- or interspecific competition were evident by 11 days following the onset of competition. The competitive impact of both weeds tended to increase with time. Growth reductions in cotton due to competition were associated primarily with reductions in leaf area duration; during drought the net assimilation rate also was reduced. Relative yields of cotton confirmed that interspecific competition from the weeds was more severe than intraspecific competition. Imposed drought did not affect the relative competitive abilities of the three species or the impact of the weeds on cotton.