Effect of irrigation and nitrogen on yield and yield components of two rapeseed cultivars

A field experiment was carried out to determine the effect of irrigation and nitrogen on two cultivars of oilseed crops (Brassica napus L, cv. canola and Brassica campestris; L. cv rapeseed) on a sandy-clay-loam soil during 1993-1994. The mean plant height ranges for canola were: 1.20-1.40 m (well water) and 1.40-1.57 m (aquaculture effluent); and for rapeseed from 1.281.52 m (well water) and 1.41-1.58 m (aquaculture effluent) in different fertilizer treatments. Mean biomass yield for canola ranged between 14.60-17.84 Mg ha(-1) (well water) and 14.09-19.51 Mg ha(-1) (aquaculture effluent); and for rapeseed from 16.67-19.51 Mg ha(-1) (well water) and 12.70-20.74 Mg ha(-1) (aquaculture effluent). The mean seed yield for canola varied from 2.65-3.44 Mg ha(-1) (well water) and 3.02-3.74 Mg ha(-1) (aquaculture effluent): and for rapeseed from 2.73-3.26 Mg ha(-1) (well water) and from 2.62-3.29 Mg ha(-1) (aquaculture effluent). The mean straw yield ranges for canola were: 12.01-14.39 Mg ha(-1) (well water) and 13.65-15.93 Mg ha(-1) (aquaculture effluent); and for rapeseed from 11.67-13.28 Mg ha(-1) (well water) and 9.83-17.45 Mg ha(-1) (aquaculture effluent). The mean oil contents for canola were 30.92-36.12% (aquaculture effluent) and 32.47-35.78% (well water); and for rapeseed from 30.15-34.53% (aquaculture effluent) and 33.50-35.96% (aquaculture effluent). The mean protein contents of straw were 5.42-6.44% (canola) and 3.78-4.37% (rapeseed) in different fertilizer treatments, Application of 175 kg N ha(-1) with 50 kg P ha(-1) showed significant effect on crop yield under both types of irrigation water. Based on the results of this study, it appears that cultivars of rapeseed recently introduced from Canada have an excellent potential as oilseed crops in Saudi Arabia.