Effect of irrigation disruption and biological phosphorus on the biomass and seed yield of canola (Brassica napus L.)

ABSTRACT: To evaluate effect of irrigation (irrigation disruption at beginning of flowering, end of flowering, grain filling and control) and biological phosphorus (0, 50, 100 and 150 g/ha) on the yield of Brassica napus L. cv. “Hyola 401”, a split plot experiment was carried out based on randomized complete block design with four replications at the research farm of Shahid Beheshti Agriculture College (latitude 38° 51ʹ N and longitude 41° 44ʹ E and 1313 m above sea level) in 2010. Results of ANOVA showed the significant effect of irrigation disruption on 1000 seed weight, and significant interaction effect between irrigation disruptions and phosphorus on number of complete pods, seed yield, biomass and Harvest Index (HI) of seed. Means comparisons indicated that the maximum (4.55 mg) and minimum (3.25 mg) single seed weight belonged to irrigation disruption at the beginning of flowering with 150 and 50 g/ha of biological phosphorus application, respectively. The highest yield of seed (777.58 kg/ha) and HI of seed (9.69 %) was obtained from irrigation disruption at the end of flowering and 50 g/ha biological phosphorus, and the lowest seed yield (120.87 kg/ha) and HI of seed (1.78 %) was obtained from irrigation disruption at the beginning of flowering and without phosphorus. The maximum number of complete pods (17.38) was observed in 150 g/ha of biological phosphorus usage at normal irrigation and the lowest number of complete pods (5.49) belonged to no phosphorus application in irrigation interrupted at the beginning of flowering stage. Means comparisons showed that the highest biomass (10223.32 kg/ha) belonged to normal irrigation with 50 g/ha phosphorus application. The lowest biomass (6826.65 kg/ha) belonged to no phosphorus treatment and irrigation disruption at the beginning of flowering stage.