1- Aktinoye H.A., Lucas E O., and Kling J.G. 1997. Effects of density of planting and time of nitrogen application on maize varieties in different ecological zones of West Africa. Communications in Soil Science and Plant Analysis. 28: 1163 – 1175.
2- Andres G. B. R. 2006. Root development and soil nitrogen availability as driver of maize-weed. competition.MS Thesis Presented to the Faculty of the Graduate School of Cornell University.
3- Berenguer P., Sativeri F., Boixadera J., and LIoreras J. 2009. Nitrogen fertilization of irrigated maize under Mediterranean conditions.Europe Journal Agronomy. 30: 163-171.
4- Blackshaw R. E., Brandt R. N., Janzen H. H., Entz T., Greant C. A., and Derksen D. A. 2003. Differential response of weed species to added nitrogen. Weed Science. 51:532-539.
5- Blackshaw R.E., Anderson R.L., and Lemerle D. 2008. Cultural Weed Management. Pages 35-47 in Upadhyaya, M.K., and Blackshaw, R.E., eds. Non-chemical Weed Management: Principles, Concepts andTechnology. Oxfordford shire, UK: CABI.
6- Costa C., Stevart L.M., and Smith D.L. 2002. Nitrogen effects on grain yield and yield components of early and nonleafy maize genotypes. Crop Science.42:1556-1563.
7- Cathcart R.J., and Swanton C.J. 2004. Nitrogen management will influence threshold values of green foxtail (Setaria viridis) in corn. Weed Science. 51: 975-986.
8- Crews T.E., and Peoples M. B. 2004. Legume versus fertilizer sources of nitrogen: Ecological tradeoff s and human needs. Agric. Ecosyst. Environ. 102:279–297.
9- Dang D., Hamayun M., Latif khan A., Shinwari Z., Kim Y., Kang S., Lee J., Inna C., Nawaz Y., Kang K., and Junglee I. 2010. Germination of some important weeds influenced by red light and nitrogenous compounds. Pak. J. Bot. 42(6):3739-3745.
10- Deihimfar R. 2005. Evaluation of the morph physiological characteristics effects on yield increase of some Triticum asetivum L. University of Tehran, abooreihan campus., 135P.
11- Evans P. S., Knezevic Z. J., Lindquist L., and Shapiro C. A. 2003 b. Influence of nitrogen and duration of weed interfrence on corn growth and development. Weed Science. 51: 546-556.
12- Harbur M. M., and Owen M. D. K. 2004. Light and growth rate effects on crop and weed responses to nitrogen. Journal of Weed Science, 52:845-853.
13- Hosseini T. 2005. Study of nitrogen on critical period of weeds control in corn (Zea mays L.). MSc thesis. Agriculture Faculty Ferdowsi university of Mashhad. (in Persian with English abstract)
14- Kogbe J. O. S., and Adediran J. A. 2003. Influence of nitrogen, phosphorus and potassium application on theyield of maize in the Savanna Zone of Nigeria. African Journal. Biology.2 (10):345 - 349.
15- Makarian H. 2002. Study of competition aspects of corn (Zea mays L.) and redroot pigweed (Amaranthus sp.) in two date of planting and different density. MSc thesis. Agriculture Faculty. Ferdowsi university of Mashhad.(in Persian with English abstract)
16- Marashi SK., Zakenejad S., Lak Sh., and Siadat SA. 2007. Effect of different planting patterns and plant densities on yield and yield components of flint corn (Zea mays L. hybrid KSC704) in Ahwaz climate condition. Journal of Scientific Agriculture. 30(3): 63-70.
17- Oktem A., Oktem A.G., and Emeklierc H.Y. 2010.Effect of nitrogen on yield and some quality parameters of sweet corn. Soil Science. Plant Anal. J. 41: 832– 847.
18- Prasad K., and Singh P. 1990. Response of promising rainfed maize (Zea mays L.) varieties to nitrogen application in North Western Hymalayan region. Indian Journal of Agricultural Sciences. 60: 475-477.
19- Roozbahani T., Akbari Gh., and Baghestani M. A. 2009. Population dynamic of weeds in corn (Zea mays L.). Third conference of Iranian weeds science. 1: 327-330.(in Persian)
20- Sepehri A. S., Modaressadavi A. M., Gharehriazi B., and Yamini Y. 2002. Effect of water tension and different levels of nitrogen on growth stages and yield and yield components of corn (Zea mays L.). Journal of Iranian Agronomy science. 4 (3): 184-200. (in Persian)
21- Smil V. 2001. Enriching the Earth.MIT Press, Cambridge, MA.
22- Smith S. W., Betran J., and Runge E. C. A. 2004. Corn (origin, History, Technology, and prodaction). Published by John Wiley & Sons, Inc Hoboken. New Jersey.
23- Togay N., Tepe I., Togy Y., and Cig F. 2009. Nitrogen levels and application methods affect weed biomass, yield and yield components in ‘Tir’ wheat (Triticum aestivum). New Zealand Journal of Crop and Horticultural Science. 37: 105-111.
24- Tajdari H. 2002. Effects of nitrogen fertilizer levels and its amortization patterns on yield and other characters of two maize cultivars in Golpaiegan region. M.Sc. Thesis, Islamic Azad University, Khorasgan Branch, Khorasgan, Iran. 121 pp. [In Persian with English Abstract].
25- Tollenaar M., Nissanka S.P., Aguilera A., Weise S.F., and Swanton C.J. 1994. Effect of weed interference and soil nitrogen on four corn hybrids. Agronomy Journal. 86: 596–601.
26- Tollenaar M., Aguilera A., and Nissanka S. P. 1997. Grain yield is reduced more by weed interference in an old than in a new maize hybrid. Agronomy Journal. 89: 239-246.
27- Torbert H.A., Potter K.N., and Morrison J.E. 2001. Tillage system, fertilizer nitrogen rate and timing effect on corn yields in the Texas Blackland prairie. Agronomy. Journal. 93:1119-1124.
28- Uhart S.A., and Andrade F.H. 1995. Nitrogen deficiency in maize: II. Carbon-nitrogen interaction effects on kernel number and grain yield. Crop Science. 35: 1384-1389.
29- Vafabakhsh K. 1995. Study of effect of different methods of control on weeds competition and yield and yield components of corn (Zea mays L.). MSc thesis. Agriculture Faculty. Ferdowsi university of Mashhad. (in Persian with English abstract)
30- Williams M.M., Boydston R.A., and Davis A.S. 2008. Differential Tolerance in Sweet corn to Wild-proso Millet (Panicum miliaceum) Interference. Weed Science. 56: 91-96.