Effects of elevated CO2 concentration,irrigation and nitrogenous fertilizer application on the growth and yield of spring wheat in semi-arid areas |
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| Authors: | Wenlong Li Xiaozhuo Han Yanyu Zhang Zizhen Li |
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| Institution: | 1. School of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou 730000, China;2. Key Laboratory of Arid and Grassland Agroecology, The Ministry of Education, Lanzhou University, Lanzhou 730000, China;3. School of Mathematics and Statistics, Lanzhou University, Lanzhou 730000, China |
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| Abstract: | In this paper, we discuss the effect of elevated CO2 concentration, irrigation and nitrogenous fertilizer application on the growth and yield of spring wheat in semi-arid areas. A field experiment was conducted at the Dingxi Agricultural Experiment Station during 2000–2002. According to the experimental design, the CO2 concentration increased to 14.5, 40 and 54.5 μmol mol−1, respectively, by NH4HCO3 (involving CO2) application, direct application of CO2 gas and combination of fertilizer NH4HCO3 plus CO2 application, which are equal to CO2 concentration of the Earth's atmosphere in the next 5, 15 and 20 years. The fertilizer application was divided into three levels: application of NH3NO3 (250 kg h m−2), NH4HCO3 (500 kg h m−2) and no fertilizer. Irrigation was divided into two levels: with 90 mm irrigation in the growth period and without irrigation. They can be combined as eight treatments. Each treatment was replicated three times. The results showed that elevated CO2 concentration owing to CO2 application leads to remarkable increase in leaf area index (LAI) and shoot biomass, and also generates the higher value of leaf area duration (LAD) that can benefit the photosynthesis in the growth stage and yield increase in crop compared than the no CO2 application treatment. When CO2 concentration elevated by 14.5, 40 and 54.5 μmol mol−1 with irrigation and fertilization, correspondingly, the grain yield increased by 6.3, 13.1 and 19.8%, respectively, whereas without irrigation and fertilization, the grain yield increased by only 4.2% when CO2 concentration increased to 40 μmol mol−1. Meanwhile, irrigation and fertilization can result in larger and deeper root system and have significantly positive influences on higher value of root/shoot (R/S) and water use efficiency. The grain yields in irrigation, irrigation plus NH3NO3 application and irrigation plus application of NH4HCO3 treatments are 73.4, 148.0 and 163.6% higher than that of no-irrigated and no-fertilized treatment, suggesting that both irrigation and fertilizer application contribute to remarkable increase of crop yield. In all treatments, the highest water use efficiency (WUE, 7.24 kg h m−2 mm−1) and grain yield (3286 kg h m−2) consistently occurred in the treatment with 90 mm irrigation plus fertilizer NH4HCO3 and elevated CO2 concentration (54.5 μmol mol−1), suggesting that this combination has an integrated beneficial effect on improving WUE and grain yield of spring wheat. These results may offer help to maintain and increase the crop yields in semi-arid areas. |
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| Keywords: | Elevated CO2 concentration Grain yield Irrigation and fertilization Semi-arid areas Spring wheat Water use efficiency |
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