Abstract
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 (P n) and intercellular CO2 concentration (C i) of maize. Similarly, the stomatal conductance (G s) and transpiration rate (T r) 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 (P nmax) and light saturation points (LSP) were increased under elevated [CO2] and irrigation, and dark respiration (R d) 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.
Highlights
The CO2 concentration ([CO2]) in the atmosphere is about 390 mmol?mol21 as a consequence of fossil fuel combustion and deforestation, which is predicted to reach 550 mmol?mol21 by the middle of this century [1]
Extensive previous studies have reported that elevated [CO2] significantly improved water use efficiency, lower transpiration rate, shorten maize growth period, and increased plant height, leaf number, leaf area, growth rate and yield [2,3,4,5,6,7,8,9,10,11,12]
According to the national standard of the Classification of Meteorological Drought (GB/T20481-2006) [50], we can see that the natural precipitation treatments are in-fact under slight drought
Summary
The CO2 concentration ([CO2]) in the atmosphere is about 390 mmol?mol as a consequence of fossil fuel combustion and deforestation, which is predicted to reach 550 mmol?mol by the middle of this century [1]. Elevated [CO2] is an important abiotic factor, and has significant fertilization effects on crops. It has been estimated that this effect would bring about a 10% increase or decrease in water resources at different areas [14]. It has been predicted that the rainfall decrease will be noticed in middle-andlower regions of Yangtze River (24uN–34uN,108uE–122uE), while the rain belts are likely to move towards north of China and precipitation would increase in Northeast China in the future [18]. The crop growth of Northeast China will likely be affected by both elevated [CO2] and increasing precipitation, which are important abiotic factors that directly or indirectly affect crop growth, physiological processes and productivity. It is necessary to understand the interactive effects of elevated [CO2] and increasing precipitation on crop growth in Northeast China under future climate change
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