Department of Biochemistry & Molecular Biology, MS330, University of Nevada, Reno, NV 89557-0330, USA
Voinovich School of Leadership and Public Affairs and Department of Environmental and Plant Biology, Ohio University, Athens, OH 45701, USA.
J Exp Bot. 2015 Jul;66(14):4177-93. doi: 10.1093/jxb/erv087. Epub 2015 Apr 1.
Global climate change is predicted to increase heat, drought, and soil-drying conditions, and thereby increase crop sensitivity to water vapour pressure deficit, resulting in productivity losses. Increasing competition between agricultural freshwater use and municipal or industrial uses suggest that crops with greater heat and drought durability and greater water-use efficiency will be crucial for sustainable biomass production systems in the future. Agave (Agavaceae) and Opuntia (Cactaceae) represent highly water-use efficient bioenergy crops that could diversify bioenergy feedstock supply yet preserve or expand feedstock production into semi-arid, abandoned, or degraded agricultural lands, and reclaim drylands. Agave and Opuntia are crassulacean acid metabolism species that can achieve high water-use efficiencies and grow in water-limited areas with insufficient precipitation to support traditional C3 or C4 bioenergy crops. Both Agave and Opuntia have the potential to produce above-ground biomass rivalling that of C3 and C4 crops under optimal growing conditions. The low lignin and high amorphous cellulose contents of Agave and Opuntia lignocellulosic biomass will be less recalcitrant to deconstruction than traditional feedstocks, as confirmed by pretreatments that improve saccharification of Agave. Refined environmental productivity indices and geographical information systems modelling have provided estimates of Agave and Opuntia biomass productivity and terrestrial sequestration of atmospheric CO2; however, the accuracy of such modelling efforts can be improved through the expansion of field trials in diverse geographical settings. Lastly, life cycle analysis indicates that Agave would have productivity, life cycle energy, and greenhouse gas balances comparable or superior to those of traditional bioenergy feedstocks, but would be far more water-use efficient.
预计全球气候变化将增加热量、干旱和土壤干燥条件，从而增加作物对水汽压亏缺的敏感性，导致生产力损失。农业淡水资源利用与城市或工业用途之间的竞争日益激烈，这表明未来具有更高耐热性和耐旱性以及更高用水效率的作物对于可持续生物质生产系统至关重要。龙舌兰（Agavaceae）和仙人掌（Cactaceae）是高效用水的生物能源作物，可以使生物能源原料供应多样化，同时在半干旱、废弃或退化的农业土地上保持或扩大原料生产，并开垦旱地。龙舌兰和仙人掌是景天酸代谢物种，可以实现高效率用水，并在降水不足不足以支持传统 C3 或 C4 生物能源作物的水分限制地区生长。在最佳生长条件下，龙舌兰和仙人掌都有可能产生与 C3 和 C4 作物相当的地上生物量。龙舌兰和仙人掌木质纤维素生物质的低木质素和高无定形纤维素含量比传统原料更不易分解，这一点通过改善龙舌兰糖化的预处理得到了证实。精炼的环境生产力指数和地理信息系统建模提供了龙舌兰和仙人掌生物量生产力和陆地大气 CO2 封存的估计值；然而，通过在不同地理环境中扩大田间试验，可以提高此类建模工作的准确性。最后，生命周期分析表明，龙舌兰的生产力、生命周期能源和温室气体平衡与传统生物能源原料相当或更优，但用水效率要高得多。
