The unavoidable plant groups of any agricultural lands are weeds. Weeds reduce crop performance through their allelopathic effects whereby they release certain substances into the environment that inhibit plants growth. Among the long lists of weeds is the redroot pigweed, which is botanically known as Amaranthus retroflexus. Pigweed is an annual green vegetable that exhibits the C4 photosynthetic pathway. This gives it the ability to grow and survive so well even under high temperature and harsh weather conditions.This weed is originally from America before spreading to other parts of the world such as Asia, Europe, Canada and Africa except Antarctica.
Redroot pigweed inhibits the germination and growth of plant crops such as rice, spinach, fluted pumpkin, cucumber, maize, green amaranthus, alfalfa, wheat and beans. Most species are resistant to herbicides such as diuron, atrazine, metribuzin, linuron, cyanazine, simazine and imazaquin.
Pigweed is also known as common pigweed, prostrate pigweed (A. graecizans), careless weed, palmer pigweed (A. palmeri), common amaranth, rough pigweed, pigweed, amaranth or smooth pigweed (A. hybridus). Even though it is a weed, yet it is edible. Pigweed stout stem grows uprightly from approximately 10 cm to 3 meters high. The greenish flowers are usually small and clustered into coarse spikes at the apex of the plant.
The green or reddish green leaves usually alternate on the erect stem. Pigweed is distinguished by the clusters of greenish flowers that form at the apex of the plant. Amaranth seeds can be dark, light-brown or dark-brown in colour. Some important pigweed species include; spiny amaranth (A. spinosus), redroot pigweed (A. retroflexus), livid amaranth (A. lividus, A. blitum), smooth pigweed (A. hybridus) and waterhemp (A. rudis).
Benefits of Redroot Pigweed
Pigweed leaves can be eaten as a fresh vegetable or used for cooking assorted dishes such as yam and vegetables, stew or soup. The leaves can be steamed, sautéed, fried or cooked with spices and seasonings. Both the fresh or dry pigweed leaves can be used to making tea. Sprouted pigweed seeds can be added to salads while the tiny pigweed seeds can be roasted, crushed and used as cereal substitute.
Pacifico et al., (2008) studied the antioxidant activity of the methanolic extract of redroot pigweed. They also evaluated the terpene components of this weed. The antioxidant properties of each metabolite were ascertained by investigating their tendency to scavenge the DPPH radical and the pro-oxidant hydrogen peroxide.
Furthermore, their capacity to inhibit the formation of thiobarbituric acid reactive species (TBARS), and to induce the formation of a phosphomolybdenum complex were examined. From the results, it is evident that the methanolic extract of the plant possesses a strong dose-response antioxidant activity. The pure nerolidol derivatives also showed antioxidant capacities comparable to those exhibited by the standard α-tocopherol.
Pigweed plant can be used for preparing herbal medicines for treating and healing wounds. The seed oil can be applied on acne, burns or rashes.
Pigweeds are very colourful and good looking thus can be planted around the house for decoration.
DISCLAIMER This post is for enlightenment purposes only and should not be used as a replacement for professional diagnosis and treatments. Remember to always consult your healthcare provider before making any health-related decisions or for counselling, guidance and treatment about a specific medical condition.
1] Bensch C. N., Horak M. J. and Peterson D., (2003), Interference of redroot pigweed (Amaranthus retroﬂexus), Palmer amaranth (A. palmeri), and common waterhemp (A. rudis) in soybean, Weed Science 51: pp.37–43.
2] Chivinge, O.A. and Schwappenhauser, M.A., 1995. Competition of soybean with blackjack (Bidens pilosa L.) and pigweed (Amaranthus hybridus L.). African Crop Science Journal, 3(1), pp.73-82.
3] Culpepper AS, Grey TL, Vencill WK, Kichler JM, Webster TM, Brown SM, York AC, Davis, J. W. and Hanna W. W. (2006) Glyphosate-resistant palmer amaranth (Amaranthus palmeri) confirmed in Georgia. Weed Sci 54: pp. 620-626.
4] Gossett, B. J. and Toler, J. E., (1999), Differential control of Palmer amaranth (Amaranthus palmeri) and smooth pigweed (Amaranthus hybridus) by postemergence herbicides in soybean (Glycine max), Weed technology, pp.165-168.
5] Jha, P., Norsworthy, J. K., Riley, M. B., Bielenberg, D. G. and W. Bridges Jr., (2008), Acclimation of palmer amaranth (Amaranthus palmeri) to shading,” Weed Science, vol. 56, no. 5, pp. 729–734.
6] Kahramanoglu I., Uygur F. (2010), The effects of reduced doses and application timing of metribuzin on redroot pigweed (Amaranthus retroflexus L.) and wild mustard (Sinapis arvensis L.), Turkish Journal of Agriculture and Forestry, 34: pp. 467–474
7] Konstantinović, B., Blagojević, M., Konstantinović, B., and Samardžić, N. (2014), Allelopathic Effect of Weed Species Amaranthus retroflexus L. on Maize Seed Germination.” Romanian Agricultural Research 31: 1-7.
8] Ma X, Wu H, Jiang W, Ma Y, Ma Y (2015) Interference between Redroot Pigweed (Amaranthus retroflexus L.) and Cotton (Gossypium hirsutum L.): Growth Analysis. PLoS ONE 10(6): e0130475. doi:10.1371/journal.pone.0130475
Pacifico, S. D’Abrosca, B., Golino, A., Mastellone, C., Piccolella, S. and Fiorentino, A. (2008), Antioxidant evaluation of polyhydroxylated nerolidols from redroot pigweed (Amaranthus retroflexus) leaves, LWT – Food Science and Technology, Volume 41, Issue 9, pp. 1665–1671.
9] Reiofeli A Salas, Nilda R Burgos, Patrick J Tranel, Shilpa Singh, Les Glasgow, Robert C Scott, Robert L Nichols. (2016) Resistance to PPO-inhibiting herbicide in Palmer amaranth from Arkansas. Pest Management Science 72:10.1002/ps.2016.72.issue-5, 864-869.
10] Sarabi, V., Rashed-Mohassel, M. H., and Valizadeh, M. (2011), Response of Redroot Pigweed (Amaranthus retroflexus L.) to Tank Mixtures of 2,4-D Plus MCPA with Foramsulfuron.” Australian Journal of Crop Science, 5 (5): 605-10.
11] Smith D. T, Baker R. V. and Steele G. L. (2000), Palmer amaranth (Amaranthus palmeri) impacts on yield, harvesting, and ginning in dryland cotton (Gossypium hirsutum). Weed Technology; 14: 122–126. doi: 10.1614/0890-037x(2000)014[0122:paapio]2.0.co;2