Asian Journal of Crop Science1994-78792077-2041Asian Network for Scientific Information10.3923/ajcs.2009.58.62MussaviS.H. AlamisaeidKh. FathiGh. GharinehM.H. Moradi-TelavatM.R. SiahpooshA. 1200911In order to investigate of rice and barnyard-grass in
different levels of herbicide and crop density, an experiment was conducted
in split plot design with four replicate, in research farm of Ramin Agriculture
and Natural Resources University in 2006. Four herbicide doses (0, 3,
5 and 7 L ha-1) was arranged in main plots and three seeding
rates (100, 120 and 140 kg seed ha-1) in subplots. Interaction
of herbicide and crop density on dry matter and yield of rice and barnyard-grass
was significant. Therefore, response of variance trends of these traits
to herbicide in different densities was different. While no herbicide
was be used, rice yield in density 120 was higher than other densities,
that showed that optimum crop density could increased crop competition
ability and decreased herbicide use. In other hand, it be observed that
highest and lowest yield of crop and weed, respectively, was be related
to 5 L herbicide ha-1. In this case, there was little difference
between different densities. With more herbicide use, probably due to
toxicity effect, crop yield decreased. However, in this herbicide dose,
density 120 showed lesser changes in crop yield. In density 120, crop
and weed yield relationship have lesser slope in comparison with other
densities. Ultimately, it seems that optimum crop density can lessen crop
sensitivity to other environmental and agronomic factors including weed
competition and herbicide use.]]>Brain, P., B.J. Wilson, K.J. wright, G.P. Seavers and J.C. Cassely,1999392135Christensen, S.,1994342936Gomez, K.A. and A.A. Gomez,19842nd Edn.,Pages: 704Pages: 704Kevin, D.G., E.H. James, C.F. Theodore, P.C. Barney and J.F. Albert,200193326332Kim, D.S., E.J.P. Marshall, P. Brain and J.C. Caseley,200646492502Lesnik, M.,2003492935Radosevich, S., J. Holt and C. Ghersa19972nd Edn.,Salsonen, J.,199232483491Shibayama, H.,200115360