Fecundity and maternal effects on Palmer amaranth height following season-long interference in corn, cotton, and peanut

Palmer amaranth (Amaranthus palmeri Watson) is one of the most difficult-to-control weeds in several economically important crops in the United States. Growth characteristics of Palmer amaranth can be affected by the cropping system. Research was conducted in North Carolina in 2019 to determine height and seed production of Palmer amaranth grown season long in the presence of corn (Zea mays L.), cotton (Gossypium hirsutum L.), and peanut (Arachis hypogaea L.). Research was also conducted to determine transgenerational effects due to interference from these crops. Palmer amaranth produced more seed when grown with cotton (17 times greater) and peanut (12 times greater) compared with corn; no difference was noted between cotton and peanut. Palmer amaranth height in the field at physiological maturity was similar in corn (80 inches) and cotton (77 inches) and taller in height than peanut (63 inches). When progeny from plants in the field were grown in the greenhouse in the absence of crop interference, differences in the height of progeny and height of the mother plant in the presence of crop interference were ranked similarly with respect to crop. Palmer amaranth height in the presence of corn and cotton was similar (57 and 58 inches, respectively) and it exceeded height when the weed was grown with peanut (51 inches). These results demonstrate transgenerational effects due to previous crop (e.g., corn, cotton, and peanut) for Palmer amaranth.