Effects of Planting Date and Density on the Seed Yield and its Components in Soybean Lines

In order to evaluate the effects of sowing date and plant density on the yield of soybean lines, a research was conducted at Miandoab Agricultural Research Station. The experimental design was factorial with three replications and repeated for two years (2001-3). The sowing date included three dates (April 21, May 15 and May 20) and sowing density included three levels of 30, 40 and 50 plants per m2 with two advanced soybean lines from the crosses of Williams × Chippewa and Williams × Collombus. During the growth period all agronomical characters were measured. Combined analysis of varianes indicated that the effects of plant density, sowing date, line, year × sowing date, plant density × line and sowing date × line × year on grain yield were significant. At 50 plants per m2, the line Williams × Chippewa produced highest grain yield (2866 kg/ha). The highest grain yield (3667 kg/ha) was obtaind in the second sowing date of the second year for the line orginated from the Williams × Chippewa. It was concluded that the line from the Williams x Chippewa cross was hight yielding than the other line. This line also producted the highest yield in the sowing date of May 15 at the density of 50 plants per m2.