Leaf Nitrogen Traits in Response to Plant Density and Nitrogen Supply in Oilseed Rape

Marcelo H Labra,Daniel F Calderini,Jochem B Evers,Paul C Struik

doi:10.3390/agronomy10111780

Marcelo H Labra, Daniel F Calderini + Show 2 more

Open Access

https://doi.org/10.3390/agronomy10111780

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Abstract

Understanding the response of plant nitrogen (N) and carbon (C) economies in oilseed rape, as well as their role in defining phenotypic plasticity, is necessary for designing new strategies to optimize plant and canopy C assimilation to improve potential yield. This paper aims to elucidate the extent to which the interaction between N supply and plant population density alters N distribution in oilseed rape plant (Brassica napus L.) and whether this interaction changes plant investment in leaf area or leaf mass per area. Spring oilseed rape was grown at two rates of N supply (50 and 150 kg N·ha−1) and two plant population densities (50 and 150 plants·m−2). Photosynthesis, leaf area, leaf biomass, and N content of selected leaves were measured at 20% of flowers on main raceme open. The interaction between N supply and plant population density altered leaf N content per area, which is the main determinant of photosynthesis. This interaction also affected leaf mass per area, while N supply determined N content per unit leaf mass. These results suggest that the interaction between N supply and population density affects both nitrogen distribution and leaf mass per area, which could have important implications for light distribution and, therefore, for C assimilation at the plant level.

Highlights

During the last 50 years, oil crops have been the commodities with the greatest relative increase in terms of contribution to the world’s food supply [1]
The current study addresses the following research questions: (1) to what extent does the interaction between N supply and plant population density affect N distribution in oilseed rape? (2) does the plant respond to this interaction by modifying assimilate investment in leaf area or by modifying leaf mass per area (LMA)?
Plant and Leaf Characteristics means of the Fischer least significant difference (LSD) test, and, when only two N level or densities times of emergence (BBCH 10), formationMaterials)

Summary

Introduction

During the last 50 years, oil crops have been the commodities with the greatest relative increase in terms of contribution to the world’s food supply [1]. The rising demand of biofuels [3] has resulted in an exponential growth of oilseed rape production since 1980, reaching 71 million tons in 2017 [4]. Future increases in crop production should be accompanied by improved sustainability of crop production systems; there is a need for developing and improving crop nitrogen (N) management which can maintain high levels of production, while minimizing N input [5], and more insight into regulatory mechanisms controlling plant N economy is vital for improving N-use efficiency [6,7]. Oilseed rape has the potential of maintaining a similar seed yield across a wide range of plant population densities [9,10], opening the opportunity to reduce sowing rates.

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