Organ-specific approaches describing crop growth of winter oilseed rape under optimal and N-limited conditions

Abstract

Abstract Carbon and nitrogen partitioning of winter oilseed rape differs under optimal and nitrogen (N) limited conditions. The quantitative description of these processes and their response to N deficiency is a prerequisite to develop process-oriented crop growth models capable to predict responses to a limited N supply. Dry matter (DM) partitioning, N dynamics and expansion of leaf, stem and pod area, as well as specific leaf area of oilseed rape were recorded during six seasons 2003/04–2005/06, and 2009/10, 2010/11 and 2012/13 within two series of field trials with varying N treatments at the experimental site Hohenschulen, northern Germany. DM partitioning is analysed using allometric relationships between leaf and stem DM as well as between stem and generative DM. The allometric relations between leaf and stem DM varied before and after beginning of stem elongation due to increasing DM allocation to stems during stem elongation. Allometric relations between DM fractions, however, were not affected by N treatment. N dilution curves, describing relations between N concentration and DM, differed between plant fractions, growth stages and N fertilization levels and indicated different response patterns under N limited conditions. This result is supported by relations between N amount and DM of leaves and stems, suggesting a sink priority for leaves under N deficiency. The approaches, describing green area expansion, dry matter partitioning and N distribution, can be used to improve dynamic crop growth models for oilseed rape.