Shahnaj Parvin1 2 3, Shihab Uddin4 5, Markus Löw5, Ute Roessner6, Sabine Tausz-Posch9, Garry O’Leary7, Glenn Fitzgerald5 7, Roger Armstrong7 8, Michael Tausz9
1Southern Cross University, Lismore, NSW, Australia
2 Charles Sturt University, Wagga Wagga, NSW, Australia
3School of Ecosystem and Forest Sciences, The University of Melbourne, Creswick, VIC, Australia.
4NSW Department of Primary Industries, Wagga Wagga Agricultural Institute, Wagga Wagga, Australia.
5Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Creswick, VIC, Australia.
6School of BioSciences, The University of Melbourne, Parkville, VIC, Australia.
7Agriculture Victoria, 110 Natimuk Road, Horsham, VIC 3400, Australia.
8Department of Animal, Plant and Soil Sciences, La Trobe University, Bundoora, VIC, Australia.
9Department of Agriculture, Science and Environment, School of Health, Medical and Applied Sciences,
CQUniversity, Rockhampton, QLD, Australia.
Elevated CO2 (e[CO2]) can stimulate N2 fixation of legumes via increases in photosynthetic carbon supply to symbionts. N2 fixation mechanisms are highly sensitive to drought but little is known about changes in nodule metabolism under e[CO2] and water restriction. To address these challenges, N2 fixation and changes of carbohydrate and nitrogen metabolic profiles were investigated in lentil (Lens culinaris MEDIK.) grown under ambient [CO2] (~400 ppm) and e[CO2] (~550 ppm) in the Australian Grain Free Air CO2 Enrichment (AGFACE) facility over two seasons with strongly contrasting rainfall. Elevated [CO2] stimulated N2 fixation to a greater extent in a wet season than in a dry season. The lower stimulation during a dry season was associated with decreased sugars and organic acids but increased concentration of sugar-alcohols and certain amino acids in nodules. Metabolic changes under e[CO2] may have contributed to mitigating drought impacts on N2 fixation of lentil.