Pakistan Journal of Biological Sciences1028-88801812-5735Asian Network for Scientific Information10.3923/pjbs.2007.3205.3209Oryza sativa L.) Varieties in North of Iran]]>MobasserHamid RezaDelarestaghiMorteza MohseniKhorgamiAli TariDavood BarariPourkalhorHamid 1220071018In order to study the effects of plant density on agronomical characteristics of rice varieties a field experiment was carried out in field of Ghaemshahr Azad University in 2006. This experiment was laid out in split plot in basis of Randomized Completely Block Design with three replications. Main factor was rice variety in three levels (Hashemi Tarom, Fajr, Neda) and minor factor was planting density (Including 10x8.3, 10x10, 12.5x10, 16.6x10, 16.6x15 and 25x20 cm or 120, 100, 80, 60, 40 and 20 plant m-2, respectively). Results showed that planting density had significant effect on plant height, total spikelets, total tillers, fertile tillers, panicle per m2, grain yield and harvest index. Days number till to 50% flowering stage and growth period length were maximum in Neda variety. Also these characteristics were not influenced by different planting densities. Maximum plant height and maximum panicle length were obtained in Hashemi Tarom variety and minimum of these characteristics were produced in Neda variety. Plant height was decreased significantly with increase of planting density.]]>Akita, K.,1982151721Baloch, A.W., A.M. Soomro, M.A. Javed, M. Ahmed, H.R. Bughio, M.S. Bughio and N.N. Mastoi,2002Oryza sativa L.).]]>12527Tari, D.B., H. Pirdashti, M. Nasiri, A. Gazanchian and S.S. Hoseini,200766165Counce, P.A.,198779864869Dowling, N.G., S.M. Greenfield and K.S. Fisher,1998pp: 404pp: 404Gravois, K.A. and R.S. Helms,19928414Hatami, H.,20022002Horie, T., T. Shiraiwa and K. Homa,20042004Huey, B.A.,1984pp: 8-12pp: 8-12Hamidul Islam, Md. and S.M. Altaf Hossain,20025513516Miller, B.C., J.E. Hill and S.R. Roberts,199183291297Mobasser, H.R., D.B. Tari, M. Vojdani, R.S. Abadi and A. Eftekhari,20076438440Nguu, N.V. and S.K. De Datta,197921934Wells, B.R. and W.F. Faw,197870477480Wu, G., L.T. Wilson and A.M. McClung,199890317323