Effect of N fertiliser application strategy on nitrogen dynamics under elevated CO2

Osmin Torres Gutierrez1, Glenn Fitzgerald1,2, Michael Tausz3, Roger Armstrong2, Sabine Tausz-Posch1

1 Department of Agriculture and Food Systems, The University of Melbourne, 4 Water St., Creswick VIC 3363, Australia. otorres@student.unimelb.edu.au

2Agriculture Victoria, Crains Innovation Park, Private Bag 260, Horsham VIC 3401, Australia

3Department of Forest and Ecosystem Science, The University of Melbourne, 4 Water St., Creswick VIC 3363, Australia.

Abstract

The atmospheric carbon dioxide concentration is increasing and is predicted to reach ~550 µmol mol-1 by 2050. As an essential resource for plant metabolism, elevated [CO2] (e[CO2]) will impact plant performance. For example, when wheat (Triticum aestivum L.) grows under e[CO2], biomass and yield are increased while grain nitrogen (N) concentration is decreased negatively affecting the nutritional quality of the grain. It has been suggested that N partitioning in plant organs and N remobilisation from vegetative plant parts to the grain is changed under e[CO2], contributing to decreased grain N under e[CO2]. The aim of this study was to investigate (1) whether targeted N fertilisation strategies can help to overcome grain N reductions under e[CO2] and (2) to evaluate the N dynamics in different plant components in response to e[CO2] conditions and contrasting N fertilisation strategies. The present study shows that biomass partitioning (leaf to stem ratio) was decreased in response to e[CO2] and increased at anthesis due to fertilisation. The N accumulation and partitioning was affected by e[CO2] in leaf and to a lesser extent in stem at anthesis but this effect was gone at maturity. The differences in N partitioning and reduced remobilisation to grain suggest a bottleneck in translocation of N that may not be solved by adding more N fertiliser to the crop under e[CO2], at least under the environmental conditions present in 2015.

Host

The Australian Society of Agronomy is the professional body for agronomists in Australia. It has approximately 500 active members drawn from government, universities, research organisations and the private sector.

Photo Credits

David Marland Photography david_marland@hotmail.com Southern Farming Systems Agriculture Victoria

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