The effects of elevated concentrations of atmospheric CO₂ (e[CO₂]) on the nutritive value of wheat vegetative matter and grain as a feedstock for ruminants were investigated in a study undertaken at the Australian grains free‐air CO₂ enrichment (AGFACE) facility. The study included two commercial wheat cultivars (Janz and Yitpi) and two genetic selections from a Seri/Babex population (SB003 and SB062) which had previously been characterised for low and high water‐soluble carbohydrate accumulation efficiency. The trial was grown under ambient (~390 µmol/mol) and elevated (~550 µmol/mol) CO₂ conditions, and plants harvested at tillering, anthesis and physiological maturity. Composition analyses to determine the nutritive value for ruminant feed were undertaken on stems, leaves and grain. Plant and grain nitrogen were reduced in the e[CO₂] treatments, and as expected, the water‐soluble carbohydrates increased. All genotypes responded to e[CO₂] with the effects of altered composition evident within 60 days of sowing. Determinants of ruminant feed quality such as neutral and acid detergent fibre and estimated in vitro metabolisable energy were not significantly affected. The reduced plant and grain N will impact on the nutritive value and supplementation may be required. The impact of e[CO₂] on chemical composition of wheat plants may be greater if the predicted climate change is associated with concomitant abiotic stress such as high ambient temperature or low soil moisture.

中文翻译：

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二氧化碳含量升高会影响植物的氮和水溶性碳水化合物，但不会影响体外代谢能

在澳大利亚谷物自由空气CO ₂富集（AGFACE）进行的一项研究中，研究了大气CO ₂（e [CO ₂ ]）浓度升高对小麦营养物质和谷物作为反刍动物原料的营养价值的影响。设施。这项研究包括两个商业小麦品种（Janz和Yitpi）和两个Seri / Babex种群的遗传选择（SB003和SB062），这些品种以前具有低和高水溶性碳水化合物积累效率的特点。该试验在环境温度（〜390 µmol / mol）和升高的（〜550 µmol / mol）CO ₂下生长条件，以及分till，花期和生理成熟期收获的植物。对茎，叶和谷物进行成分分析以确定反刍动物饲料的营养价值。在e [CO ₂ ]处理中，植物和谷物中的氮减少，并且如预期的那样，水溶性碳水化合物增加。所有基因型均对e [CO ₂ ]有反应，播种后60天内明显改变了组成。反刍动物饲料质量的决定因素（例如中性和酸性洗涤剂纤维）以及估计的体外代谢能没有受到显着影响。减少的植物和谷物N将影响营养价值，可能需要补充营养。e [CO ₂的影响如果预测的气候变化与伴随的非生物胁迫（例如高环境温度或低土壤湿度）相关，则小麦植物化学成分的含量可能会更高。