Fertilizer response for hybrid and open-pollinated canola and economic optimal nutrient levels

Abstract

Smith, E. G., Upadhyay, B. H., Favret, M. L. and Karamanos, R. E. 2010. Fertilizer response for hybrid and open-pollinated canola and economic optimal nutrient levels. Can. J. Plant Sci. 90: 305-310. Hybrid (HY) canola (Brassica napus L.) produces a higher seed yield than open-pollinated (OP) canola. While it is expected higher-yielding HY canola may require higher total available nutrients, especially nitrogen (N), the evidence is not conclusive. This study used canola yield data from several site-years and fertility experiments to determine whether HY and OP canola types require different rates of total available N (TAN) and total available phosphorus (TAP). The yield response of the two canola genotypes to TAP was the same, but for TAN the yield response was greater for HY canola. The quadratic yield response results were confirmed using three plateau equations. Optimal TAN for HY canola was higher than for OP canola. Soil test laboratories and producers growing HY canola need to modify N fertility for HY canola, compared with OP canola for which most of the current N fertilizer recommendations were developed.