The effect of different levels of phosphorus and nitrogen fertilizers on rape seed after rice harvest in north of Iran

摘要

At present and in order to provide sufficient vegetable oil for domestic consumption we have turned to global market. Domestic production of vegetable oil is about 100000 tons while its consumption rates exceed 850000 tons in Iran yearly. This huge difference is supplied by importing. The surface area under cultivation in the northern regions of Iran is over 460000 hectares which for the most part is only used in the first six mounts of the year .these paddies are absolutely useless in the second half of the year .rape seed is therefore one of the products that can be used as double cropping after harvest of rice paddies. This experiment was a completely randomized factorial design with three replicates and was conducted in an experimental field inlahijan in 2005-2006.the first factor was included of three levels of phosphorus fertilizer (pl=0, p2=50, p3=100 kg/ha) and the last factor contained four different levels of nitrogen fertilizers (nl=0, n2=100/ n3=150, n4=200 kg/ha. Considering most of surveyed characteristics and compared to other levels, n4 has shown superiority. Number of silique in bush had the most effect on seed yield and percentage of oil seed with increase in consumption of nitrogen fertilizer had decreased. The excessive consumption of phosphorus fertilizer has always been among critical issues and great concern in rice paddies of northern Iran and the results of this experiment showed non significance between different levels of Phosphorus fertilizer.