Winter wheat has a central role in ensuring the food security and welfare of 1.3 billion people in China. Extensive previous studies have concluded that winter wheat yields would decrease with higher temperatures, owing to warming-induced soil drying or shortening of
Winter wheat has a central role in ensuring the food security and welfare of 1.3 billion people in China. Extensive previous studies have concluded that winter wheat yields would decrease with higher temperatures, owing to warming-induced soil drying or shortening of phenophase. Temperature in China is predicted to increase by 1–5°C by 2100, which may greatly impact plant production and cause other negative effects. We performed a manipulative field experiment, creating diverse growth regimes for wheat by infrared radiation (IR) warming day and night, including IR warming only (DW), IR warming + delayed sowing dates (DS), IR warming + increased irrigation (IW), and a control (CK). The results show that IR warming increased daily average wheat canopy and soil temperatures by 2.0°C and 2.3°C, respectively. DW was associated with an advanced maturity of 10 days and yield reduction of 8.2%. IR-warming effects on the photosynthetic apparatus of wheat varied with season as well as significant differences were found in the booting stage. DS represented a worsened situation, lowering yield per plant by 16.4%, with a significant decline in aboveground biomass and functional leaf area. Wheat under DS showed double-peak patterns of diurnal gas exchange during booting stages and, consequently, lower photosynthetic capacity with high transpiration for cooling. Significantly lower actual water use efficiency and intrinsic water use efficiency from jointing to anthesis stages were also found under DS. However, IW had no significant difference from CK, irrespective of yield and photosynthesis. Therefore, we concluded that delayed sowing date may not be a good choice for winter wheat, whereas a thoroughly-watered wheat agroecosystem should be promoted in the context of global warming.
Citation: Fang S, Su H, Liu W, Tan K, Ren S (2013) Infrared Warming Reduced Winter Wheat Yields and Some Physiological Parameters, Which Were Mitigated by Irrigation and Worsened by Delayed Sowing. PLoS ONE 8(7): e67518. https://doi.org/10.1371/journal.pone.0067518
Editor: Carl J. Bernacchi, University of Illinois, United States of America
Received: January 11, 2013; Accepted: May 23, 2013; Published: July 9, 2013
Copyright: © 2013 Fang et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Funding: This research was jointly supported by National Research Institutes of Basic Research and Operating Expenses of China (Grant No. 2008Y005) and National Basic Research Program of China (Grant No. 2010CB951300). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing interests: The authors have declared that no competing interests exist.
Global mean surface air temperature increased by about 0.5°C during the 20th century, and is projected to increase further by 1.8°C to 4.0°C by the end of this century. Temperature in China has increased by 1.2°C since 1960, and is estimated to increase further by 1–5°C by 2100. Warming will greatly impact plant production,, and additional negative effects have been found in temperate crop cultivation areas. Ottman et al. (2012) reported that grain yield of wheat declined 6.9% per 1°C increase in seasonal temperature above 16.3°C at Maricopa, AZ. Mitchell et al. (1995) found that warming by 4.0°C reduced winter wheat phytomass and yield by 20–30% in the UK. Asseng et al. (2010) observed variations in average growing-season temperatures of ±2°C in the main wheat growing regions of Australia, and found reductions in grain production up to 50%. Fang et al. (2010) found that nocturnal warming of 2.5°C caused 27% declines of winter wheat yield in northern China. Long-term observations,, manipulative experiments  and model simulations  have also demonstrated negative impacts of rising temperatures on biomass production and yield of other crop species. However, underlying mechanisms of crop response to climatic warming and consequent influences on crop biomass production and yield remain elusive.
Winter wheat is the foremost cereal-grain food in the world and an essential source of carbohydrates, especially in China. It has a central role in ensuring the food security and welfare of 1.3 billion people. Several studies have found that reduction in winter wheat yields with higher temperatures may be due to warming-induced soil drying,  or shortening of phenophase. Warming-induced change in growth environments would certainly affect crop-water relationships,  and/or photosynthesis,,, which are the principal determinants of total crop biomass. Today, because of little effort toward increasing the proportion of biomass allocated to grains, increasing total crop biomass may be more important for achieving greater yields. Therefore, it is essential to investigate the effects of warming on photosynthetic capacities and wheat biomass, and to find countermeasures to prevent their reduction.
The use of infrared radiation (IR) heaters to condu