The weed suppression ability of different soybean varieties was studied in a field experiment in 2010. The experiment was carried out in a randomized complete block design using a split-plot arrangement with 3 replicates. The main plots were either weedfree (hand weeding) or infested with the natural weed population (weedy). Six soybean varieties (Sari, Telar, Sahar, Hill, 032 and 033) were randomized within the main plots. The relative biomass total (RBT), relative crowding coefficient (RCCcw) and competitive balance index (Cb) were recorded and were regressed against crop traits under weedy conditions. The results showed a reduction in the maximum height of the soybean varieties under weedy conditions. No significant relationship was found between weed biomass and the canopy height of the varieties. Competition indices and the weed suppressive ability of soybean showed intergenotypic variation in competitive ability between the varieties tested. Weed pressure reduced the yield and yield components of all the soybean varieties. Under weedy conditions the soybean variety Hill gave a higher economic yield than the others, with high weed biomass suppression ability.
Balyan, R. S. R., Malik, K., Panwar, R. S., Singh, S. (1991): Competitive ability of winter wheat cultivars with wild oat (Avena ludoviciana). Weed Sci., 39, 154–158.
Singh S. , 'Competitive ability of winter wheat cultivars with wild oat (Avena ludoviciana) ' (1991 ) 39 Weed Sci. : 154 -158 .
Buhler, D. D., Hartzler, R. G. (2004): Weed biology and management. pp. 883–918. In: Boerma, H. R., Specht, J. E. (eds.), Soybeans: Improvement, Production, and Uses. Third ed. Series Agronomy, No. 16. American Society of Agronomy. Madison, WI.
Hartzler R. G. , '', in Soybeans: Improvement, Production, and Uses , (2004 ) -.
Bussan, A. J., Burnside, O. C., Orf, J. H., Ristau, E. A., Puetmann, K. J. (1997): Field evaluation of soybean (Glycine max) genotypes for weed competitiveness. Weed Sci., 45, 31–37.
Puetmann K. J. , 'Field evaluation of soybean (Glycine max) genotypes for weed competitiveness ' (1997 ) 45 Weed Sci. : 31 -37 .
Callaway, M. B. (1992): A compendium of crop varietal tolerance to weeds. Am. J. Alternative Agr., 7, 169–180.
Callaway M. B. , 'A compendium of crop varietal tolerance to weeds ' (1992 ) 7 Am. J. Alternative Agr. : 169 -180 .
Christensen, J. (1995): Weed suppression ability of spring barley varieties. Weed Res., 35, 241–247.
Christensen J. , 'Weed suppression ability of spring barley varieties ' (1995 ) 35 Weed Res. : 241 -247 .
Dhima, K. V., Eleftherohorinos, I. G., Vasilakoglou, I. B. (2000): Interference between Avena sterilis, Phalaris minor and five barley cultivars. Weed Res., 40, 549–559.
Vasilakoglou I. B. , 'Interference between Avena sterilis, Phalaris minor and five barley cultivars ' (2000 ) 40 Weed Res. : 549 -559 .
Didon, U. M. E., Boström, U. (2003): Growth and development of six barley (Hordeum vulgare ssp. vulgare L.) cultivars in response to a model weed (Sinapis alba L.). J. Agron. Crop Sci., 189, 409–417.
Boström U. , 'Growth and development of six barley (Hordeum vulgare ssp. vulgare L.) cultivars in response to a model weed (Sinapis alba L.) ' (2003 ) 189 J. Agron. Crop Sci. : 409 -417 .
Dingkuhn, M., Johnson, D. E., Sow, A., Audebert, A. Y. (1999): Relationships between upland rice canopy characteristics and weed competitiveness. Field Crop Res., 61, 79–95.
Audebert A. Y. , 'Relationships between upland rice canopy characteristics and weed competitiveness ' (1999 ) 61 Field Crop Res. : 79 -95 .
Fischer, A. J., Ramirez, H. V., Gibson, K. D., Pinheiro, B. D. S. (2001): Competitiveness of semi dwarf upland rice cultivars against palisadegrass (Brachiaria brizantha) and signalgrass (B. decumbens). Agron. J., 93, 967–973.
Pinheiro B. D. S. , 'Competitiveness of semi dwarf upland rice cultivars against palisadegrass (Brachiaria brizantha) and signalgrass (B. decumbens) ' (2001 ) 93 Agron. J. : 967 -973 .
Gooding, M. J., Thompson, A. J., Davies, W. P. (1993): Interception of photosynthetically active radiation, competitive ability and yield of organically grown wheat varieties. Asp. Appl. Biol., 34, 355–362.
Davies W. P. , 'Interception of photosynthetically active radiation, competitive ability and yield of organically grown wheat varieties ' (1993 ) 34 Asp. Appl. Biol. : 355 -362 .
Jannink, J. K., Orf, J. H., Jordan, N. R., Shaw, R. G. (2000): Index selection for weed suppressive ability in soybean. Crop Sci., 40, 1087–1094.
Shaw R. G. , 'Index selection for weed suppressive ability in soybean ' (2000 ) 40 Crop Sci. : 1087 -1094 .
Joshi, N. C. (2001): Weed Control Manual. 5th edition. Delhi Research Station, Delhi, India. 538 p.
Joshi N. C. , '', in Weed Control Manual , (2001 ) -.
Karimmojeni, H., Rahimian Mashhadi, H., Shahbazi, H., Taab, A. R., Mohammad Alizadeh, H. (2010): Competitive interaction between maize, Xanthium strumarium and Datura stramonium affecting some canopy characteristics. Aust. J. Crop Sci., 4, 684–691.
Mohammad Alizadeh H. , 'Competitive interaction between maize, Xanthium strumarium and Datura stramonium affecting some canopy characteristics ' (2010 ) 4 Aust. J. Crop Sci. : 684 -691 .
Lemerle, D., Verbeek, B., Coombes, N. E. (1996): Interaction between wheat (Triticum aestivum) and diclofop to reduce the cost of annual ryegrass (Lolium rigidum) control. Weed Sci., 44, 634–639.
Coombes N. E. , 'Interaction between wheat (Triticum aestivum) and diclofop to reduce the cost of annual ryegrass (Lolium rigidum) control ' (1996 ) 44 Weed Sci. : 634 -639 .
Lemerle, D., Verbeek, B., Orchard, B. (2001): Ranking the ability of wheat varieties to compete with Lolium rigidum. Weed Res., 41, 197–209.
Orchard B. , 'Ranking the ability of wheat varieties to compete with Lolium rigidum ' (2001 ) 41 Weed Res. : 197 -209 .
Mohammadi, G. R. (2007): Growth parameters enhancing the competitive ability of corn (Zea mays L.) against weeds. Weed Biol. Manag., 7, 232–236.
Mohammadi G. R. , 'Growth parameters enhancing the competitive ability of corn (Zea mays L.) against weeds. ' (2007 ) 7 Weed Biol. Manag. : 232 -236 .
Monks, D. W., Oliver, L. R. (1988): Interactions between soybean (Glycine max) cultivars and selected weeds. Weed Sci., 36, 770–776.
Oliver L. R. , 'Interactions between soybean (Glycine max) cultivars and selected weeds ' (1988 ) 36 Weed Sci. : 770 -776 .
Paolini, R., Del Puglia, S., Principi, M., Barcellona, O., Riccardi, E. (1998): Competition between safflower and weeds as influenced by crop genotype and sowing time. Weed Res., 38, 247–255.
Riccardi E. , 'Competition between safflower and weeds as influenced by crop genotype and sowing time ' (1998 ) 38 Weed Res. : 247 -255 .
Paolini, R., Faustini, F., Benedetti, G. (2002): Early growth and competitive ability of durum wheat (Triticum durum Desf.) varieties. pp. 266–267. In: Proceedings 12th Symposium EWRS, Wageningen, Netherlands.
Benedetti G. , '', in Proceedings 12th Symposium EWRS , (2002 ) -.
Paolini, R., Faustini, F., Saccardo, F., Crino, P. (2006): Competitive interactions between chickpea genotypes and weeds. Weed Res., 46, 335–344.
Crino P. , 'Competitive interactions between chickpea genotypes and weeds ' (2006 ) 46 Weed Res. : 335 -344 .
Pester, T. A., Burnside, O. C., Orf, J. H. (1999): Increasing crop competitiveness to weeds through crop breeding. J. Crop Production, 2, 59–76.
Orf J. H. , 'Increasing crop competitiveness to weeds through crop breeding ' (1999 ) 2 J. Crop Production : 59 -76 .
Satorre, E. H., Snaydon, R. W. (1992): Root and shoot competition between spring cereals and Avena fatua L. Weed Res., 32, 45–55.
Snaydon R. W. , 'Root and shoot competition between spring cereals and Avena fatua L ' (1992 ) 32 Weed Res. : 45 -55 .
Scott, G. H., Askew, S. D., Wilcut, J. W., Brownie, C. (2000): Datura stramonium interference and seed rain in Gossypium hirsutum. Weed Sci., 48, 613–617.
Brownie C. , 'Datura stramonium interference and seed rain in Gossypium hirsutum ' (2000 ) 48 Weed Sci. : 613 -617 .
Snaydon, R. W. (1991): Replacement or additive designs for competition studies? J. Appl. Ecol., 28, 930–946.
Snaydon R. W. , 'Replacement or additive designs for competition studies? ' (1991 ) 28 J. Appl. Ecol. : 930 -946 .
Vollmann, J., Wagentristl, H., Hartl, W. (2010): The effects of simulated weed pressure on early maturity soybeans. Europ. J. Agron., 32, 243–248.
Hartl W. , 'The effects of simulated weed pressure on early maturity soybeans ' (2010 ) 32 Europ. J. Agron. : 243 -248 .
Wilson, J. B. (1988): Shoot competition and root competition. J. Appl. Ecol., 25, 279–296.
Wilson J. B. , 'Shoot competition and root competition ' (1988 ) 25 J. Appl. Ecol. : 279 -296 .