Elevated atmospheric CO2 concentrations (e[CO2]) can decrease the grain quality
of wheat. However, little information
exists concerning interactions between e[CO2] and nitrogen
fertilization on important grain quality traits. To investigate this,
a 2-year free air CO2 enrichment (FACE) experiment was
conducted with two CO2 (393 and 600 ppm) and three (deficiency,
adequate, and excess) nitrogen levels. Concentrations of flour proteins
(albumins/globulins, gliadins, and glutenins) and key minerals (iron,
zinc, and sulfur) and baking quality (loaf volume) were markedly increased
by increasing nitrogen levels and varied between years. e[CO2] resulted in slightly decreased albumin/globulin and total gluten
concentration under all nitrogen conditions, whereas loaf volume and
mineral concentrations remained unaffected. Two-dimensional gel electrophoresis
revealed strong effects of nitrogen supply and year on the grain proteome.
Under adequate nitrogen, the grain proteome was affected by e[CO2] with 19 downregulated and 17 upregulated protein spots.
The downregulated proteins comprised globulins but no gluten proteins.
e[CO2] resulted in decreased crude protein concentration
at maximum loaf volume. The present study contrasts with other FACE
studies showing markedly stronger negative impacts of e[CO2] on chemical grain quality, and the reasons for that might be differences
between genotypes, soil conditions, or the extent of growth stimulation
by e[CO2].
Increasing CO2 concentration ([CO2]) is thought to induce climate change and thereby increase air temperatures and the risk of drought stress, the latter impairing crop growth. The objective of this study was to investigate the effects of elevated [CO2] and drought stress on root growth of one maize genotype (Zea mays cv. Simao) and two sorghum genotypes (Sorghum bicolor cv. Bulldozer and Sorghum bicolor × Sorghum sudanense cv. Inka) under the cool moderate climate of Central Europe. It was hypothesized that root growth stimulation due to elevated [CO2] compensates for a reduced root growth under drought stress. Therefore, we established an experiment within a free‐air carbon dioxide enrichment system (FACE) in 2010 and 2011. Sorghum and maize genotypes were grown under ambient [CO2] (385 ppm CO2) and elevated [CO2] (600 ppm CO2) and in combination with restricted and sufficient water supply. Elevated [CO2] decreased root length density (RLD) in the upper soil layers for all genotypes, but increased it in deeper layers. Higher [CO2] enhanced specific root length (SRL) of “Simao” and “Bulldozer,” however, did not affect that of “Inka.” “Simao” achieved a higher SRL than the sorghum genotypes, indicating an efficient investment in root dry matter. Although elevated [CO2] affected the root growth, no interaction with the water treatment and, consequently, no compensatory effect of elevated [CO2] could be identified.
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