Tschaplinski T J, Stewart D B, Hanson P J, Norby R J
Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6034, USA.
Department of Plant Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA.
New Phytol. 1995 Jan;129(1):63-71. doi: 10.1111/j.1469-8137.1995.tb03010.x.
Interactions between elevated atmospheric CO and drought on growth and gas exchange of American sycamore (Platanus occidentalis L.), sweetgum (Liquidambar styraciflua L.) and sugar maple (Acer saccharum Marsh.) were investigated using 1-yr-old seedlings, planted in 8 1 pots and grown in four open-top chambers, containing either ambient air or ambient air enriched with 300 μmol mol CO . Two soil moisture regimes were included within each chamber: a 'well-watered' treatment with plants watered daily and a 'drought' treatment in which plants were subjected to a series of drought cycles. Duration and depth of the drought cycles were determined by soil matric potential. Mean soil water potential at rewatering for the water-stressed seedlings under ambient CO for sugar maple, sweetgum and sycamore was -0.5, -0.7 and -1.8 MPa, respectively, compared with > -0.1 MPa for all well-watered plants. Elevated CO increased relative growth rate of well-watered sugar maple by 181%, resulting in a 4.3-fold increase in total plant dry weight after 81 d, compared with 1.4 and 1.6-fold increases for sweetgum and sycamore, respectively, after 69 d. Although elevated CO increased net CO assimilation rate of sugar maple by 115%, there was a 10-fold increase in leaf area which contributed to the growth response. Although drought did not eliminate a growth response of sugar maple to elevated CO it greatly reduced the elevated CO -induced enhancement of relative growth rate. In contrast, relative growth rates of sweetgum and sycamore were not significantly increased by elevated CO . Drought, under elevated CO , reduced leaf area of all three species to a greater extent than it reduced net CO assimilation rate. The response ranged from no effect in sugar maple to a 40 % reduction in sycamore, with sweetgum exhibiting an intermediate response. Results indicate that drought may alter the growth response, gas exchange and water relations of tree species growing in an elevated CO atmosphere. Under high nutrient and water availability, sugar maple may benefit the most (of the three species studied) from a CO - enriched atmosphere, but productivity gains will be limited if frequent drought is prevalent.
利用一年生幼苗，研究了大气中二氧化碳浓度升高与干旱对美国梧桐（Platanus occidentalis L.）、胶皮糖香树（Liquidambar styraciflua L.）和糖枫（Acer saccharum Marsh.）生长及气体交换的相互作用。幼苗种植于8升花盆中，在四个开放式气室中生长，气室内分别通入环境空气或添加300 μmol mol二氧化碳的富集空气。每个气室内设置两种土壤水分处理：一种是“充分浇水”处理，每天给植株浇水；另一种是“干旱”处理，使植株经历一系列干旱循环。干旱循环的持续时间和深度由土壤基质势决定。在环境二氧化碳浓度下，糖枫、胶皮糖香树和美国梧桐受水分胁迫的幼苗复水时的平均土壤水势分别为-0.5、-0.7和-1.8 MPa，而所有充分浇水的植株均大于-0.1 MPa。二氧化碳浓度升高使充分浇水的糖枫相对生长速率提高了181%，81天后植株总干重增加了4.3倍，相比之下，胶皮糖香树和美国梧桐在69天后分别增加了1.4倍和1.6倍。虽然二氧化碳浓度升高使糖枫的净二氧化碳同化率提高了115%，但叶面积增加了10倍，这对生长响应有促进作用。虽然干旱并未消除糖枫对二氧化碳浓度升高的生长响应，但大大降低了二氧化碳浓度升高诱导的相对生长速率增强。相比之下，二氧化碳浓度升高并未显著提高胶皮糖香树和美国梧桐的相对生长速率。在二氧化碳浓度升高的情况下，干旱对所有三个物种叶面积的减少幅度大于对净二氧化碳同化率的减少幅度。响应程度从糖枫无影响到美国梧桐减少40%不等，胶皮糖香树表现出中等响应。结果表明，干旱可能会改变在二氧化碳浓度升高环境中生长的树种的生长响应、气体交换和水分关系。在高养分和高水分供应条件下，糖枫（在所研究的三个物种中）可能从二氧化碳富集的大气中受益最大，但如果频繁发生干旱，生产力的提高将受到限制。
