Effects of nitrogen and planting density on yield and oil content of castor (Ricinus communis L.)

Effects of plant population and nitrogen application was studied for the agronomical traits and growth indexes of castor. A split plot experiment based on a randomized complete block design with four replications was carried out at Esmaeilabad Educational Center of Ghazvin Province in 2006. Different nitrogen amounts were applied included four nitrogen levels (0, 40, 80, 120 kg/ha) and different plant density included 2.5, 4 and 5.5 plants/m2. The results revealed that the highest and the lowest yield and oil obtained where 120 kg and 0 kg nitrogen per hectare were applied, respectively. Plant densities revealed significant differences for all characteristics. The highest and least yield and oil obtained from 5.5 and 2.5 plants/m2, respectively. The intraction of nitrogen and plant density showed a significant effect on characteristics such as weight of claster, number of seeds per plant, number of seeds per square meter, weight of 1000 seeds, and seed yield. The highest weight of claster, the high number of seeds per plant and high weight of 100 seeds resulted in the interaction of the plant density of 2.5 plants/m2 and 120 kg/ha. The lowest values were belonging to the density of 5.5 plants/m2 and no nitrogen applied. High number of seeds/m2 and high yield were resulted from the interaction of density of 5.5 plants/m2 and 120 kg nitrogen/ha. Consequently, 120 kg/ha notrogen fertilizer with 5.5 plants/m2 are recommended for high yield and high oil content.