| Effects of nitrogen level and rewatering degree after drought priming on water use efficiency of wheat |
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| DOI：10.7606/j.issn.1000-7601.2022.05.06 |
| Key Words: wheat nitrogen application rate drought\|rehydration water use efficiency δ13C |
| Author Name | Affiliation | | XING Jiayi | Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences, State Engineering Laboratory of Efficient Water Use of Crops and Disaster Loss Mitigation, Key Laboratory of Dryland Agriculture, Ministry of Agriculture and Rural Affairs, Beijing 100081, China | | LI Li | Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences, State Engineering Laboratory of Efficient Water Use of Crops and Disaster Loss Mitigation, Key Laboratory of Dryland Agriculture, Ministry of Agriculture and Rural Affairs, Beijing 100081, China | | WANG Chao | Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences, State Engineering Laboratory of Efficient Water Use of Crops and Disaster Loss Mitigation, Key Laboratory of Dryland Agriculture, Ministry of Agriculture and Rural Affairs, Beijing 100081, China | | HAO Weiping | Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences, State Engineering Laboratory of Efficient Water Use of Crops and Disaster Loss Mitigation, Key Laboratory of Dryland Agriculture, Ministry of Agriculture and Rural Affairs, Beijing 100081, China | | WANG Yaosheng | Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences, State Engineering Laboratory of Efficient Water Use of Crops and Disaster Loss Mitigation, Key Laboratory of Dryland Agriculture, Ministry of Agriculture and Rural Affairs, Beijing 100081, China |
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| Abstract: |
| A pot experiment in the greenhouse was conducted with the variety ‘XR4347’ of winter wheat to investigate the effects of nitrogen application and rewatering level after drought priming on physiological characteristics and water use efficiency of wheat. Three nitrogen levels consisted of low nitrogen (N0.5, 74 mg·kg-1), medium nitrogen (N1.5, 223 mg·kg-1) and high nitrogen (N3, 446 mg·kg-1), and three water treatments under each nitrogen level comprised rewatering to 85% of soil water holding capacity (SWHC) after drought priming (40% of SWHC) (W85), rewatering to 60% of SWHC after drought priming (W60) and re\|drought stress to 40% of SWHC after drought priming (W40). The results showed that rewatering after drought priming improved the water status of plants. However, the high degree of rewatering reduced the root water potential (RWP) of wheat under medium and low nitrogen treatments. Stomatal conductance (gs) of leaves was regulated by both hydraulic and abscisic acid (ABA) signals. There was a significant negative correlation between intrinsic water use efficiency (WUEint) and gs, therefore, reducing the degree of rewatering or increasing nitrogen fertilization improved WUEint by regulating gs. A high degree of rewatering after drought priming increased plant leaf area (LA), shoot dry biomass (SDB) and plant water use (PWU), and promoted nitrogen uptake, but reduced root growth. Compared with the degree of rewatering, nitrogen level more pronouncedly affected plant water use efficiency (WUEp). High nitrogen treatment reduced PWU by 9% and increased WUEp by 10% while ensuring SDB accumulation. Besides, leaf carbon isotope composition (δ13C) increased with the increase in nitrogen level, and there was a significant positive correlation between WUEp and leaf δ13C, indicating that leaf δ13C could be used to surrogate the WUEp under drought priming, and the increase of nitrogen application reduced PWU by long\|term regulating the stomatal opening of leaves, thereby improved WUEp. In all the treatments, N3W85 and N3W60 treatments improved WUEp while ensured the accumulation of SDB. Moreover, the N3W60 treatment significantly reduced PWU by 10.4% and the root\|shoot ratio was relatively high, which was more conducive to the growth of wheat plants and saved irrigation water. The N3W60 treatment was the most optimal treatment for this experiment. Therefore, in arid and water\|deficient areas, increasing the amount of nitrogen application or rewatering appropriately after drought priming not only significantly reduced PWU, saved irrigation water and maintained crop growth and nutrient absorption, but also improved WUE at plant and leaf scale. |
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