Tausz-Posch, Sabine and Dempsey, Raymond W. and Seneweera, Saman and Norton, Robert M. and Fitzgerald, Glenn and Tausz, Michael (2015) Does a freely tillering wheat cultivar benefit more from elevated CO2 than a restricted tillering cultivar in a water-limited environment? European Journal of Agronomy, 64. pp. 21-28. ISSN 1161-0301
Abstract
This study addresses whether a freely tillering wheat cultivar with greater vegetative sink strength (cv. 'Silverstar') can benefit more from increasing atmospheric CO2 concentration [CO2] than a restricted tillering cultivar with greater reproductive sink strength (cv. H45) in a water-limited cropping system. Growth, yield, yield components and nitrogen at three developmental stages (stem elongation, anthesis, maturity) and water soluble carbohydrates (WSC, anthesis) were evaluated at two CO2 concentrations (ambient [CO2], ~395ppm, elevated e[CO2], ~550ppm) across six environments using the Australian Grains Free Air CO2 Enrichment (AGFACE) facility. Cv. 'Silverstar' had more tillers than cv. 'H45' throughout development; whereas, cv. 'H45 had greater WSC storage and more and heavier kernels per spike. CO2 enrichment stimulated grain yield in both cultivars similarly, but this stimulation was caused differently: For cv. 'Silverstar', grain yield increase was exclusively linked to an increased number of fertile tillers; whereas, in cv. 'H45', yield stimulation was additionally associated with increased kernel weight and kernel numbers per spike. We conclude that in a Mediterranean-type, water-limited environment high tillering capacity alone does not ensure greater benefits from CO2 fertilization but that both pre and post-anthesis source-sink relationships play a significant role in this environment as well.
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