Carbon Dioxide and Temperature Effects on Evapotranspiration and Water Use Efficiency of Soybean

Abstract

Rising CO2 and potential global warming will cause changes in evapotranspiration (ET). Our research objective was to determine the impact of CO2 and air temperature on canopy ET, water use efficiency (WUE), foliage temperature, and canopy resistance (Rc) of soybean [Glycine max (L.) Merr.]. Plants were grown in sunlit, controlled‐environment chambers at cyclic maximum/minimum air temperatures from 28/18°C to 44/34°C and CO2 of 350 or 700 μmol mol−1 Maximum ET rate in the early afternoon at 35 d after planting ranged from 7.5 mol m−2 s−1 at 28/18°C to 19.0 mol m−2 s−1 at 44/34°C. Daily ET during the middle of the season ranged from 260 mol H2O m−2 d−1 (4.7 mm d−1) at 28/18°C to 660 mol H2O m−2 d−1 (11.9 mm d−1) at 44/34°C. Mean daily ET was linearly related to mean air temperature (Tair) as: [Mean daily ET = 21.4 × Tair − 306, r2 = 0.99 (mol H2O m−2 d−1), or mean daily ET = 0.385 × Tair − 5.5 (mm d−1)]. Doubled CO2 caused a 9% decrease in ET at 28/18°C, but CO2 had little effect at 40/30°C or 44/34°C. Whole‐day WUE declined linearly with air temperature, with a slope of −0.150 [(μmol CO2 mmol−1 H2O) °C−1]. Changes in ET and WUE were governed by changes in foliage temperature and Rc. In conclusion, increases in temperature anticipated by climate change could more than offset decreases of ET that would be caused by increases in CO2

Adapting wheat sowing dates to projected climate change in the Australian subtropics: analysis of crop water use and yield

“…Figure 5b shows that increasing [CO 2 ] from 380 to 600 ppm increased WUE by 37% for the NI, by 27% for the DI, and by 23% for the FI scenario. These findings agree with results reported by Boote et al (1997) and Allen et al (2003) on soybean and wheat. For the DI and NI scenarios, the positive impact of increased [CO 2 ] on WUE was mostly due to an increase in crop yield, since the corresponding change in crop ET was quite small.…”

Spatial variations of rain-use efficiency along a climate gradient on the Tibetan Plateau: A satellite-based analysis

“…Our study proved that at the spatial scale an increase in temperature caused an increase in RUE across various ecosystems or within a given ecosystem in the alpine area, which was supported by a modelling study in a tallgrass prairie (Bell, Weng, and Luo 2010). Some reports have come to a different conclusion, in that ecosystem WUE reduced under a warmer climate (Allen et al 2003;de Boeck et al 2006), possibly due to the lower carbon uptake rate resulting from stomatal regulation (Niu et al 2008), which could be a water-saving adaptive mechanism to drier conditions (Niu et al 2011). However, for alpine areas characterized by high elevation and low temperature, temperature was positively correlated with vegetation density (Li, Liu, and Fu 2011) and was considered the most important factor for vegetation growth (Chen et al 2010).…”

Weather Conditions in the 2013 -2015 Growing Seasons for Maize in Croatia and Bosnia and Herzegovina

“…Degree of arable land utilization is a serious problem of agriculture in both countries because about 40% of arable land is unfarmed (Table 1).Average air temperatures for April-September period in eight selected meteorological stations were 18.2 0 C (2013), 17.7 0 C (2014) and 18.8 0 C (2015) and they are higher in comparison with 1961-1990 average (16-9 0 C). These data are in accordance with climate change toward global warming (Allen et al, 2003;Chi-Chung et al, 2004;FAO, 2007;Jolankai and Birkas, 2013). Precipitation in April-September period of 2013 and 2014 (Table 2) in Bijeljina (373 mm and 731 mm), Tuzla (443 mm and 1021 mm), Banja Luka (370 mm and 1228 mm) and Bihac (479 mm and 1135 mm) are in agreement with this opinion.…”