Amthor Jeffrey S, Mitchell Robert J, Runion G Brett, Rogers Hugo H, Prior Stephen A, Wood C Wesley
Health and Ecological Assessment Division and Global Climate Research Division, L-256, Lawrence Livermore National Laboratory, PO Box 808, Livermore, California 94550-9900, USA.
Joseph W. Jones Ecological Research Center, PO Box 2324, Newton, Georgia 31770, USA.
New Phytol. 1994 Nov;128(3):443-450. doi: 10.1111/j.1469-8137.1994.tb02990.x.
Grain sorghum [Sorghum bicolor (L.) Moench, a C crop] and soybean [Glycine max (L.) Merr. cv. Stonewall, a C crop] plants were grown in ambient (c. 360μl 1 ) and twice-ambient (c. 720 μl 1 ) CO levels in open-top chambers in soil without root constriction. Plant dry mass, energy content, composition and construction cost (i.e. amount of carbohydrate required to synthesize a unit of plant dry mass) were assessed at the end of the growing season. Elevated CO (a) increased phytomass accumulation (kg per plant) in both species, (b) had little affect on energy concentration (MJ kg plant) but caused large increases in the amount of plant energy per ground area (MJ m ground), and (c) did not alter specific growth cost (kg carbohydrate kg plant growth) but greatly increased growth cost per ground area (kg carbohydrate m ground) because growth was enhanced. For soybean, twice-ambient CO resulted in a 50 % increase in the amount of nitrogen and energy in grain (seed plus pod) per ground area. This response to elevated CO has important implications for agricultural productivity during the next century because the rate of human population growth is exceeding the rate of increase of land used for agriculture so that future food demands can only be met by greater production per ground area.
在无根系限制的土壤中，将高粱[Sorghum bicolor (L.) Moench，一种C4作物]和大豆[Glycine max (L.) Merr. cv. Stonewall，一种C3作物]植株种植于开顶式生长室内，使其处于环境CO₂浓度（约360μl L⁻¹）和两倍环境CO₂浓度（约720μl L⁻¹）条件下。在生长季结束时，对植株干质量、能量含量、组成成分和构建成本（即合成单位植株干质量所需的碳水化合物量）进行评估。CO₂浓度升高：(a)使两个物种的植株生物量积累（每株千克数）均增加；(b)对能量浓度（每千克植株兆焦）影响较小，但使单位地面面积的植株能量总量（每平方米地面兆焦）大幅增加；(c)未改变比生长成本（每千克植株生长所需的碳水化合物千克数），但因生长增强，单位地面面积的生长成本（每平方米地面所需的碳水化合物千克数）大幅增加。对于大豆，两倍环境CO₂浓度使单位地面面积籽粒（种子加豆荚）中的氮和能量含量增加50%。这种对CO₂浓度升高的响应对于下个世纪的农业生产力具有重要意义，因为人口增长率超过了农业用地的增长速度，因此未来的粮食需求只能通过提高单位地面面积的产量来满足。
