The Impact of Pigweed (Amaranthus retroflexus L.) Population on Oil Yield and Fatty Acid Composition of Castor Bean (Ricinus communis L.)

Document Type : Scientific - Research


1 Urmia

2 Agrcutural and Education research center of West Azarbayjan

3 Urmia Jihad


Castor bean, as an important commercial oil-based by products are used in the manufacture of several commercially important commodities like surfactants, coatings, greases, pharmaceuticals, cosmetics, polyesters, polymers. Castor bean is a non-edible oilseed crop which produces an oil rich in Ricinoleic acid, commonly over 80%. The seeds of castor consist of 40-60% by weight of the most useful natural plant oil. Interactive effects among species on inter-species populations are called interference. Interference is one of the main issues on the eco-physiology of plant populations where weeds impose negative effects by approaching the plant to compete in light, water and nutrient elements availability and results in reduced growth and yield. Various reasons have been attributed for the low productivity of crops, among them weed competition is the most important. Redroot pigweed belongs to the Amaranthaceae family, as an important competitor to slow growth of the castor bean plant, can deprive it from nutrients.The purpose of this research was determining the effects of redroot pigweed plant density interference on the yield of oil and fatty acids composition of castor bean plant to increase quantity and quality of oil. 
Materials and Methods
 To evaluate the effects of Pigweed interference on yield, oil content and fatty acid composition of castor oil plant, a factorial experiment was conducted based on randomized complete block design with three replications at the Center for Agricultural Research in West Azerbaijan (Urmia) (Saatlu station: 37°44´18״ N Latitude and 45° 10´ 53״ E Longitude, at 1338 m above sea level) with silty-sandy soils. The first factor included Castor plant densities (3, 4, 5 and 6 plants per square meter) and the second was Amaranth densities (zero, 5, 10 and 15 plants per square meter). Castor seeds cv. Mobarakeh were planted with red root pigweed simultaneously on 14 June 2013. After Soxhlet extraction, fatty acid analysis was performed by Gas Chromatography. Data were analyzed with SAS 9.1 software.
Result and Discussion
The results showed the significant effects of castor and amaranth densities, and their interaction effects on the castor oil yield, but only significant effect of amaranth density on the fatty acid composition. According to the results, increasing Amaranth density caused to reduction of 20-38% in castor grain yield, 39% in oil yield compared to pure cultures (without weed). Due to the unique characteristics of ricinoleic acid, it was reduced 19% by increasing pigweed density, but the palmitic acid (74%) and stearic acid (108%), linoleic acid (12%) and Oleic acid (64%) were increased compared with pure cultures (weed free). The results of the survey indicated that the pigweed at densities of 10 and 15 plants per square meter is one of the most important factors affecting yield, oil content and fatty acid composition. In this experiment, Amaranth weed caused to significant reduction of the yield of castor grain, oil and major fatty acids. In this regard, pigweed control at the beginning of the growing season will be effective to reduce seed production, in order to reducing crop yield loss and reduce the scope of its release in the next years. In general, despite the importance of castor plant there has been limited research work carried out on the crop in Iran to increase the crop competitive ability. In this present study, the oil content, oil yield and fatty acids composition of Iranian castor bean oil have been outlined. The results of this experiment showed that changes in oil content and fatty acid composition is depending on environmental conditions such as competition with weed and the Pigweed is a competitive weed which  significantly reduces the quantitative (seed and oil) and qualitative (oil composition) yield.
Increasing pigweed density decrease grain yield, oil yield and fatty acids composition of castor bean. The amount of this reduction was related to pigweed density. On the other hand, 6 plants/m2 of Castor bean can be recommended for reducing pigweed damage in Castor bean.


Aguyoh, J.M., and Masiunas, J.B. 2003.Interference of redroot pigweed (Amaranthus retroflexus) with snap beans. Weed Science 51: 202-207.
Arshi, Y., Moazaffari, K., and Zeinali, H. 1996. Survey of effect drought stress on some morphological traits and grain yield of sunflower. Iranian Journal of Seed and Plant 12(3): 296-605. (In Persian with English Summary)
Azadmard- Damirchi, S., Savage, G.P., and Dutta, P.C. 2005. Sterol fractions in hazelnut and virgin olive as possible markers for detection of adulteration of virgin olive oil. Journal of the American oil chemists Society 82: 717-725.
Azevedo, D.M.P., Beltrao, N.E.M., Nobrega, L.B., and Vieira, D.J. 2007. Plantasdaninha e seucontrole. D.M.P. Azevedo and E.F. Lima, editors. OAgronegocio da Mamona no Brasil. Embrapa Algodao/ Embrapa Informacao Tecnologica, Campina Grande, Brasilia, Brazil p. 161-189.
Cosge, B., Gurbuz, B., and Kiralan, M. 2007. Oil content and fatty acid composition of some safflower varieties sown in spring and winter. International Journal of Natural Engineering Science 1: 11-15.
Fayyaz, H., Hakoomat, A., Cheema, M.A., and Manal, A. 2005. Effects of environmental variation on oil content and fatty acid composition of canola cultivars. Journal of Research Science 16(2): 65-72.
Gana, A.K., Yusuf, A.F., and Apuyor, B. 2013. Castor oil plant and its potential in transformation and industrialization of under developing nations in the world. Advanced Journal of Agricultural Research 1(5): 72-79.
Grichar, W.J., Dorty, P.A., and Trostle, C.L. 2012. Castor (Ricinus communis L.) tolerance topostemergence herbicide and weed control efficacy. International Journal of Agronomy 832749: 1-5.
Guo, P.G., and Al-Khatib, K. 2003. Temperature effect on germination time and density on redroot pigweed (Amaranthus retroflexus), palmer amaranth (A. palmeri), and common water hemp (A. rudis). Weed Science 51: 869-875.
Gupta, S., Subrahmanyam, D., and Rathore, V.S. 1994. Influence of sowing date on yield and oil quality in sunflower. Journal of Agronomy and Crops Science 17(2): 137-144.
Gupta, S.S., Hilditch, T.P., and Riley, J.P. 1951. The fatty acids and Glycerides of castor oil. Journal of the Science of Food and Agriculture 2(6): 245-251.
Jafarzadeh, N., Pirzad, A.R., Hadi, H. 2016. Castor (Ricinus communis L.) and pigweed (Amaranthus retroflexus L.) growth indices in terms of interference. Journal of Agroecology 8(2): 182-196. (In Persian with English Summary)
Jose, R.L., Ursicino, D., and Rafael, D.Q. 1990. Definite influence of location and climatic condition on the fatty acid composition of sunflower seed oil. Journal of the American Oil Chemists Society 67(10): 618-623.
Klingman, T.E., and Oliver, L.R. 1994. Palmer amaranth (Amaranthus palmeri L.) interference in soybeans (Glycine max L.). Weed Science 42: 523-527.
Koutroubas, S.D., Papakosta, D.K., and Doitsini, A. 1999. Adaption and yielding ability of castor plant (Ricinus communis L.) genotypes in a Mediterranean climate. European Journal of Agronomy 11: 227-237.
Maciel, C.D.G., Poletine, J.P., Velini, E.D., Zanotto, M.D., Amaral, J.G., Santos, H.R., Artioli, J.C., Ferreira, R.V., Lolli, J., and Raimondi, M.A. 2007. Weeds interference periods over vegetative development characteristics of savana castor bean genotype. Revista Brasileira de Oleaginosas e Fibrosas 11: 23-29.
Mitich, L.W. 1997. Redroot pigweed (Amaranthus retroflexus). Weed Technology 11: 199-202.
Oguniyi, D.S. 2006. Castor oil: A vital industrial raw material. Bioresource Technology 97: 1086-91.
Omidbagi, R., and Alirezalu, A. 2011. Effect of sowing location on oil content and fatty acids composition of medicinal castor bean plant (Ricinus communis L.). Iranian Journal of medicinal and Aromatic plants 26(4): 521-530. (In Persian with English Summary)
Oplinger, E.S., Oeke, E.A., Kaminski, A.R., Combs, S.M., Doll, J.D., and Schuler, R.T. 1990. Castor bean production. USDA. Farmers Bulletin. No. 2041.
Palerich, D. 1987. Recent advance in the cultivation of medicinal plants. Journal of Acta Horticulture 208: 29-34.
Rezvani Moghaddam, P., Nabati, J., Norozpoor, G., and Mohamadabdi, A. 2004. Investigation on morphological characteristics, grain and oil yields of castor bean at different plant densities and irrigation intervals. Iranian Journal of Field Crops Research 2(1): 1-12. (In Persian with English Summary)
Sabzalian, M.R., Saeidi, G., and Mirloh, A. 2008. Oil content and fatty acid composition in seeds of three safflower species. Journal of the American Oil Chemistry Society 85: 717-721.
Turan, H., Citak, N., Pehlivanoglu, H., and Mengul, Z. 2010. Effects of ecological and topographic conditions on oil content and fatty acid composition in sunflower. Bulgarian Journal of Agricultural Science 16(5): 553-558.
Salimon, J., Azleema, D., Nazrizwati, A.T., MohdFirdaus, M.Y., and Noraishah, A. 2010. Fatty acid composition and physicochemical properties of Malaysian castor bean Ricinuscommunis L. seed oil. Sains Malaysiana 39(5): 761-764.
Shaheen, A.M. 2002. Morphological variation within castor bean (Ricinus communis L.) in Egypt: Fruit, Seed and Pollen. Pakistan Journal of Biology Science 5: 1202-1206.
Santos, B.M., Dusky, J.A., Stall, W.M., Shilling, D.J., and Bewick, T.A. 2007. Influence of smooth pigweed and common purslane on lettuce as affected by phosphorus fertility. In: Proceedings of the Florida State Horticultural Society.110: 315-317.
Shinggu, C.P., Mahadi, M.A., and Adekpe, D.I. 2011. Performance of castor (Ricinus communis L.) as influenced by period of weed interference in Samaru, Nigeria. International Journal of Science Natural 2(1): 75-78.
Teasdal, J.R. 1998. Influence of corn population and row spacing on corn and velvet leaf (Abutilon theophrasti) yield. Weed Science 43: 425-431.
Tollenar, M.A., Dibo, A., Aguilera, A., Weise, S.F., and Swanton, C.J. 1998. Effect of crop density on weed interference in maize. Agronomy Journal 86: 591-595.
Valadabadi, A., Alimohammadi, M. Aref, B., and Daneshian, J. 2010. Effects of different levels of nitrogen and plant density on oil yield and its component in Castor bean (Ricinus communis L.). Ecophysiological Crop 2(4): 312-318. (In Persian with English Summary)
Zimdal, R. L.1980. Weed-Crop Competition: A Review. International Plant Protection center, Corvallis, Oregon 196 pp.