Kinmonth-Schultz Hannah, Kim Soo-Hyung
Center for Urban Horticulture, School of Forest Resources, College of the Environment, University of Washington, 3501 NE 41st Street, Box 354115, Seattle, WA 98195-4115, USA.
Funct Plant Biol. 2011 Oct;38(10):797-807. doi: 10.1071/FP11060.
Reed canary grass (Phalaris arundinacea L.) is a fast-growing, perennial, rhizomatous C3 grass considered as a model invasive species for its aggressive behaviour. The same traits make it a candidate for bioenergy feedstock. We tested the following hypotheses: (1) elevated atmospheric [CO2] and nutrient supply enhance photosynthetic carbon acquisition of this fructan-accumulating grass with little or no photosynthetic downregulation; (2) elevated [CO2] promotes carbon allocation to growth when nutrients are sufficient and to fructan storage in rhizomes when nutrients are low. Plants were grown at ambient or elevated (+320μmolmol-1) [CO2], and fertilised using full or one-eighth strength modified Hoagland solution. We investigated leaf photosynthesis, whole-plant water use, biomass allocation, and nitrogen and carbon storage in rhizomes. Elevated [CO2] enhanced light-saturated net CO2 assimilation by 61%. It doubled whole-plant, stem and root biomass in summer. Plants grown in elevated [CO2] had a greater rate of CO2 assimilation at higher [CO2], indicating a shift in photosynthetic apparatus for enhanced carbon gain under elevated [CO2]. The majority of belowground biomass was allocated to rhizomes for storage rather than to roots in both seasons. In autumn, elevated [CO2] increased fructan concentration in rhizomes from 8.1 to 11.7% of biomass when nutrients were low (P=0.023). Our results suggest that elevated [CO2] combined with sufficient nutrients is likely to enhance carbon gain and growth of P. arundinacea, and to increase its productivity and competitiveness in summer. Elevated [CO2] is likely to enhance long-term fructan storage in rhizomes, which may benefit overwintering and vegetative spread.
虉草（Phalaris arundinacea L.）是一种生长迅速的多年生根茎型C3禾本科植物，因其具有侵略性的行为而被视为典型的入侵物种。同样的特性使其成为生物能源原料的候选植物。我们测试了以下假设：（1）大气中[CO2]浓度升高和养分供应增加会增强这种积累果聚糖的禾本科植物的光合碳同化，且几乎没有或没有光合下调；（2）当养分充足时，[CO2]浓度升高会促进碳分配到生长中，而当养分不足时，则会促进碳分配到根茎中的果聚糖储存中。将植物种植在环境[CO2]浓度或升高（+320μmolmol-1）的[CO2]浓度下，并使用全强度或八分之一强度的改良霍格兰溶液施肥。我们研究了叶片光合作用、整株植物水分利用、生物量分配以及根茎中的氮和碳储存。[CO2]浓度升高使光饱和净CO2同化率提高了61%。在夏季，它使整株植物以及茎和根的生物量增加了一倍。在较高[CO2]浓度下生长的植物在更高[CO2]浓度下具有更高的CO2同化率，这表明光合机构发生了转变，以在[CO2]浓度升高的情况下增强碳获取。在两个季节中，大部分地下生物量都分配到根茎中用于储存，而不是根中。在秋季，当养分不足时，[CO2]浓度升高使根茎中的果聚糖浓度从生物量的8.1%增加到11.7%（P=0.023）。我们的结果表明，[CO2]浓度升高与充足的养分相结合可能会增强虉草的碳获取和生长，并提高其在夏季的生产力和竞争力。[CO2]浓度升高可能会增强根茎中果聚糖的长期储存，这可能有利于越冬和营养繁殖。
