Meng Fanchao, Zhang Jiahua, Yao Fengmei, Hao Cui
Institute of Eco-Environment and Agro-Meteorology, Chinese Academy of Meteorological Sciences, Beijing, China; College of Atmospheric Science, Nanjing University of Information Science & Technology, Nanjing, China.
Institute of Eco-Environment and Agro-Meteorology, Chinese Academy of Meteorological Sciences, Beijing, China; Key Laboratory of Digital Earth Science, Institute of Remote Sensing and Digital Earth, Chinese Academy of Sciences, Beijing, China.
PLoS One. 2014 May 21;9(5):e98318. doi: 10.1371/journal.pone.0098318. eCollection 2014.
Maize is one of the major cultivated crops of China, having a central role in ensuring the food security of the country. There has been a significant increase in studies of maize under interactive effects of elevated CO2 concentration ([CO2]) and other factors, yet the interactive effects of elevated [CO2] and increasing precipitation on maize has remained unclear. In this study, a manipulative experiment in Jinzhou, Liaoning province, Northeast China was performed so as to obtain reliable results concerning the later effects. The Open Top Chambers (OTCs) experiment was designed to control contrasting [CO2] i.e., 390, 450 and 550 µmol·mol(-1), and the experiment with 15% increasing precipitation levels was also set based on the average monthly precipitation of 5-9 month from 1981 to 2010 and controlled by irrigation. Thus, six treatments, i.e. C550W+15%, C550W0, C450W+15%, C450W0, C390W+15% and C390W0 were included in this study. The results showed that the irrigation under elevated [CO2] levels increased the leaf net photosynthetic rate (Pn) and intercellular CO2 concentration (Ci) of maize. Similarly, the stomatal conductance (Gs) and transpiration rate (Tr) decreased with elevated [CO2], but irrigation have a positive effect on increased of them at each [CO2] level, resulting in the water use efficiency (WUE) higher in natural precipitation treatment than irrigation treatment at elevated [CO2] levels. Irradiance-response parameters, e.g., maximum net photosynthetic rate (Pnmax) and light saturation points (LSP) were increased under elevated [CO2] and irrigation, and dark respiration (Rd) was increased as well. The growth characteristics, e.g., plant height, leaf area and aboveground biomass were enhanced, resulting in an improved of yield and ear characteristics except axle diameter. The study concluded by reporting that, future elevated [CO2] may favor to maize when coupled with increasing amount of precipitation in Northeast China.
玉米是中国主要的栽培作物之一，在保障国家粮食安全方面发挥着核心作用。在二氧化碳浓度（[CO₂]）升高与其他因素的交互作用下，对玉米的研究显著增加，但[CO₂]升高与降水增加对玉米的交互作用仍不明确。本研究在中国东北辽宁省锦州市进行了一项控制实验，以获得有关后续影响的可靠结果。开顶式气室（OTC）实验旨在控制不同的[CO₂]浓度，即390、450和550 μmol·mol⁻¹，同时根据1981年至2010年5 - 9月的月平均降水量设置了降水增加15%的实验，并通过灌溉进行控制。因此，本研究包括六种处理，即C550W + 15%、C550W0、C450W + 15%、C450W0、C390W + 15%和C390W0。结果表明，[CO₂]浓度升高条件下的灌溉提高了玉米的叶片净光合速率（Pn）和胞间CO₂浓度（Ci）。同样，气孔导度（Gs）和蒸腾速率（Tr）随[CO₂]浓度升高而降低，但灌溉在每个[CO₂]水平上对它们的增加都有积极影响，导致在[CO₂]浓度升高时自然降水处理的水分利用效率（WUE）高于灌溉处理。在[CO₂]浓度升高和灌溉条件下，光响应参数，如最大净光合速率（Pnmax）和光饱和点（LSP）增加，暗呼吸（Rd）也增加。生长特性，如株高、叶面积和地上生物量得到增强，除轴径外，产量和穗部特性均有所改善。该研究最后报告称，未来在中国东北，[CO₂]浓度升高与降水量增加相结合可能有利于玉米生长。
