Effect of irrigation regime and phosphorus application methods on phosphorus recovery efficiency and grain yield of two rapeseed cultivars

To investigate the effects of water deficit and chemical phosphorus (P) application methods on yield and phosphorus recovery efficiency of two rapeseed cultivars, a field experiment was conducted at Agriculture College and Natural Resources of Darab, Shiraz University during 2013-2014. Treatments including irrigation regimes (common irrigation, cutting off irrigation at mid-flowering and mid-silique formation stages), P application methods (without P, broadcast and band) and rapeseed cultivars (Sarigol and RGS) were assigned in main plots, sub plots and sub sub plots, respectively. Results showed that cutting of irrigation at common irrigation with 25.31 seed numbers per silique had significant differences with mid-flowering with 22.25 seed numbers per silique and cutting of irrigation at mid-silique formation with 22.94 seed numbers per silique . In cutting of irrigation at mid-flowering and band application of P, RGS had the highest biological yield (12435 hg/ha). Common irrigation had the highest (11.02 kg/ha) and cutting of irrigation at mid-flowering had the lowest (5.95 kg/ha) P absorption amount. Overall, P recovery efficiency in broadcast and band application methods of P was 1.09% and 1.38%, respectively. RGS cultivar compared to Sarigol had maximum grain yield under cutting of irrigation at mid-flowering (3830 kg/ha) and mid-silique formation conditions (5428 kg/ha). RGS had the highest rate of assimilate remobilization under cutting off irrigation at mid-flowering and band application of P and it can prevent a further reduction in grain yield when exposed to late season water shortage.