More Productive Than Maize in the Midwest: How Does Miscanthus Do It?
More Productive Than Maize in the Midwest: How Does Miscanthus Do It?
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DOI：
10.1104/pp.109.139162
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发表时间：
2009-08-01
期刊：
影响因子：
7.4
通讯作者：
Long, Stephen P.
中科院分区：
文献类型：
--
作者：
Dohleman, Frank G.;Long, Stephen P.
在美国对这两种C4作物进行的首次大规模并行试验中，S.玉米带，芒草（芒）是59%以上的生产力比粮食玉米（玉米）。总生产力是每单位土地面积入射的太阳辐射总量与光截获效率（λ（i））及其转化为地上生物量（λ（ca））的乘积。在两个生长季节的平均值中，芒草的蒸腾速率（ca）没有差异，但蒸腾速率（i）比芒草高61%，芒草较早形成叶冠，并在较晚的时候保持叶冠。在26个日期的每一个物种的阳光照射和遮荫叶片的光合作用的日进程进行了测量。叶水平光合CO2吸收的每日积分略有不同时，在两个生长季节集成，但高达60%以上，在盛夏的玉米。芒属植物的平均叶面积是玉米的两倍，结果计算的冠层光合作用在芒属植物中高出44%，与生物量差异密切对应。为了确定在中期叶光合作用，光和CO2响应的差异的基础上进行了分析，以确定在体内的生化限制。玉米具有较高的磷酸烯醇式丙酮酸羧化最大速率、磷酸烯醇式丙酮酸再生速率、光合光饱和速率和CO2同化最大量子效率。然而，这些生化差异被芒属植物更大的叶面积和更长的持续时间所抵消。结果表明，现代温带玉米品种没有充分发挥C-4光合生产力的潜力。
In the first side-by-side large-scale trials of these two C 4 crops in the U. S. Corn Belt, Miscanthus (Miscanthus X giganteus) was 59% more productive than grain maize (Zea mays). Total productivity is the product of the total solar radiation incident per unit land area and the efficiencies of light interception (epsilon(i)) and its conversion into aboveground biomass (epsilon(ca)). Averaged over two growing seasons, epsilon(ca) did not differ, but epsilon(i) was 61% higher for Miscanthus, which developed a leaf canopy earlier and maintained it later. The diurnal course of photosynthesis was measured on sunlit and shaded leaves of each species on 26 dates. The daily integral of leaf-level photosynthetic CO2 uptake differed slightly when integrated across two growing seasons but was up to 60% higher in maize in mid-summer. The average leaf area of Miscanthus was double that of maize, with the result that calculated canopy photosynthesis was 44% higher in Miscanthus, corresponding closely to the biomass differences. To determine the basis of differences in mid-season leaf photosynthesis, light and CO2 responses were analyzed to determine in vivo biochemical limitations. Maize had a higher maximum velocity of phosphoenolpyruvate carboxylation, velocity of phosphoenolpyruvate regeneration, light saturated rate of photosynthesis, and higher maximum quantum efficiency of CO2 assimilation. These biochemical differences, however, were more than offset by the larger leaf area and its longer duration in Miscanthus. The results indicate that the full potential of C-4 photosynthetic productivity is not achieved by modern temperate maize cultivars.