Effects of Cycocel and Nitrogen Application on Yield and Yield Components of Autumn-Grown Oilseed Rape at Different Plant Densities

In this research, which was carried out as two experiments (in the field and greenhouse) at Research Farm of College of Agriculture, Shiraz University, Shiraz, Iran, in 2009-2010 growing season, the effects of different levels of nitrogen, plant density and cycocel application on yield and yield components of autumn-grown oilseed rape (Talaye cultivar) were investigated. The field experiment was designed as split-split plot based on completely randomized blocks design. Treatments included nitrogen level (80, 140, 200 and 260 kg/ha) as the main plot, plant density (70 and 90 plants/m2) as sub-plot and cycocel rate (0, 1.4 and 2.8 L/ha) as sub- subplot. The greenhouse experiment, which was arranged as a factorial based on complete randomized design, included nitrogen level (0, 50, 100, 150 and 200 kg/ha) and cycocel rate (0, 1.4 and 2.8 L/ha). Results showed that the highest seed yield was achieved at 200 kg N/ha, 2.8 L/ha cycocel and plant density of 90 plants/m2 (533.17, 533.96 and 521.6 g/m2, respectively). Application of 2.8 L/ha cycocel was associated with increased number of siliques per plant and final plants dry weight. Increasing plant density from 70 to 90 plants/m2 was associated with decreased number of siliques per plant, plant dry weight and number of seeds per silique. It appears that application of 200 kg N/ha, 2.8 L/ha cycocel and plant density of 90 plants/m2 could be recommended for maximum grain yield of autumn-grown rapeseed cv. Talaye, in agroclimatic conditions similar to this research.