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| Ammonia volatilization of winter wheat canopy under different nitrogen rates |
| Received:September 23, 2016 |
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| KeyWord:canopy ammonia volatilization;winter wheat;apoplastic NH4+ concentration;ammonia compensation point;glutamine synthetase(GS) |
| Author Name | Affiliation | E-mail | | JING Jian-yuan | College of Natural Resources and Environment, Northwest A & F University, Yangling 712100, China | | | SUN Xiao | College of Natural Resources and Environment, Northwest A & F University, Yangling 712100, China | | | YANG Yang | Institute of Technical Biology & Agriculture Engineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China | | | LI Na | College of Natural Resources and Environment, Northwest A & F University, Yangling 712100, China | | | TIAN Xiao-xiao | College of Natural Resources and Environment, Northwest A & F University, Yangling 712100, China | | | LÜ Shen-qiang | College of Natural Resources and Environment, Northwest A & F University, Yangling 712100, China | | | WANG Lin-quan | College of Natural Resources and Environment, Northwest A & F University, Yangling 712100, China
Key Laboratory of Plant Nutrition and the Agri-Environment in Northwest China, Ministry of Agriculture, Yangling 712100, China | linquanw@nwsuaf.edu.cn |
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| Abstract: |
| A single factor field experiment with three nitrogen rates(0, 90, and 180 kg N·hm-2) was conducted in winter wheat during the 2015-2016 growth season. Ammonia volatilization from both soil and canopy in winter wheat field were measured with the modified vented ammonia trap chambers. Glutamine synthetase(GS) activity in leaves, apoplastic NH4+ concentration and pH, and ammonia compensation point were determined simultaneously. Obtained results showed that field ammonia volatilization mainly occurred within the 2~3 weeks after N fertilization. In the whole growing season, ammonia volatilization totaled in 3.773~8.704 kg N·hm-2, and it increased significantly with the increase of N fertilization rates, of which 3.289~7.773 kg N·hm-2 were from soil, accounting for 87.2%~89.3% of the total; and 0.750~1.461 kg N·hm-2 from the canopy, accounting for 15.4%~19.9% of the total. It was found that the canopy absorbed volatilized ammonia during seedling stage under lower nitrogen application rate(90 kg N·hm-2), and during seedling, returning green and early grain filling stage under higher N application rate(180 kg N·hm-2), but did not under no N fertilization. The net canopy ammonia volatilization mainly occurred at flowering and late grain filling stage, accounting for 4.5%~9.3% and 79.1%~99.0% of total canopy ammonia volatilization during the whole growing season, respectively. Canopy ammonia fluxes were positively correlated with the ammonia compensation point and apoplastic NH4+ concentration, but showed no relation to the GS activity in leaves and apoplastic pH. In summary, winter wheat canopy volatilizes ammonia to the atmosphere past flowering no matter fertilization or not, but it absorbs ammonia from the atmosphere with N fertilization, and emits ammonia without N fertilization during the vegetative stages. |
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