Effects of nitrogen and plant density on yield of field mustard (Brassica campestris)

In order to examine the effects of different levels of N fertilization and plant density on the yield of field mustard (Brassica campestris) cv. Goldrush, a study was carried out in Qazvin, Iran in 2009-2010 as a split-plot experiment based on a randomized complete block design with three replications. The main plot was pure N from urea source at four levels of 0, 50, 100 and 150 kg.ha-1 and the sub-plot was plant density at four levels of 60, 80, 100 and 120 plants.m-2. Statistical analysis showed that different levels of plant density and N significantly affected the number of siliques per plant, the number of seeds per silique, 1000-seed weight, seed yield, oil yield, biological yield and harvest index. The increase in N level increased all these traits at all treatments. Also, higher densities up to 100 plants.m-2 led to higher values of all traits. The density of 120 plants.m-2 resulted in the lowest value of all traits at all treatments. In total, the densities of 80 and 100 plants.m-2 and the application of 100 kg N.ha-1 were considerably superior and produced the highest seed yield (3491 kg.ha-1) and oil yield (1084 kg.ha-1). Furthermore, the highest seed oil content (37.97%) was obtained at the density of 100 plants.ha-1 treated with 150 kg N.ha-1.