Competition of pigweed (Amaranthus dubius) with sweetpotato (Ipomoea batatas)

How to Cite

Semidey, N., Liu, L. C., & Ortiz, F. H. (1987). Competition of pigweed (Amaranthus dubius) with sweetpotato (Ipomoea batatas). The Journal of Agriculture of the University of Puerto Rico, 71(1), 7–11.


Two field experiments were conducted at the Isabela and Juana Díaz Research Centers in 1982-83 to determine the effect of pigweed (Amaranthus dubius Mart.) density on yield of sweetpotato [Ipomoea batatas (L.) Lam]. Pigweed densities of 0, 4, 7, 13 and 27 plants/m2 were adjusted by hand at Isabela and those of 0, 11, 23, 45 and 91 plants/mwere maintained at Juana Díaz. Pigweed population averaged 27 plants/m2 at Isabela and 91 plants/m2 at Juana Díaz under natural infestation. Sweetpotato yield was reduced significantly from 4 plants/m2 at Isabela and from 11 plants/m2 at Juana Díaz. The highest sweetpotato yield was obtained on weed-free plots with 11,823 kg/ha at Isabela and 27,724 kg/ha at Juana Díaz. The greatest yield reduction (91%) resulting from pigweed competition (at Juana Díaz) was at a density of 91 plants/m2. At Isabela, a density of 13 plants/m2 caused the greatest yield reduction (78%). The effect of pigweed on number of root-tubers followed a similar trend as the effect on yield. Dry weight of pigweed per plant was significantly greater at population densities of 4 and 7 plants/m2 at Isabela. At Juana Díaz, dry weight of pigweed was significantly higher at a population density of 11 plants/m2. The regression between sweetpotato yield and the different population densities of pigweed showed an inverse linear relationship at both localities.


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