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Shoot Growth, Phosphorus–Nitrogen Relationships, and Yield of Canola in Response to Mineral Phosphorus Fertilization
Author(s) -
Bélanger Gilles,
Ziadi Noura,
Pageau Denis,
Grant Cynthia,
Lafond Jean,
Nyiraneza Judith
Publication year - 2015
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj15.0050
Subject(s) - canola , shoot , human fertilization , phosphorus , agronomy , brassica , biomass (ecology) , fertilizer , dry matter , yield (engineering) , crop , nitrogen , chemistry , biology , materials science , organic chemistry , metallurgy
Crop responses to increasing P fertilization are often variable and poorly related to soil P test. Our objectives were to determine the influence of P fertilizer on the growth and seed yield of canola ( Brassica napus L.) and to develop a first approximation of its critical phosphorus concentration (P c ) in shoot biomass. An experiment with four rates of P fertilizer (0, 20, 40, and 80 kg P ha −1 ) was conducted on soils with a low available P content at 5 site‐years [Normandin (QC; 2010, 2011, 2012) and Brandon (MB; 2010, 2012)] in Canada. Dry matter (DM) yield, and N and P concentrations were measured weekly on 5 d from early bolting to late flowering, and seed yield was measured at harvest. Seed yield was significantly increased by P fertilization at only 1 of the 5 site‐years, even though a positive response was expected at all site‐years. Phosphorus fertilization did not affect shoot growth and P uptake at any of the 5 site‐years. However, the estimated shoot biomass on the first sampling day was reduced with no P application at 3 of the 5 site‐years. A reduction in early crop growth of more than 30%, however, was required to affect seed yield. The whole‐plant canola P c was expressed as function of N concentration (P c = 1.74 + 0.024N, R 2 = 0.24, P = 0.05) but this first approximation requires further validation.