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Virtual water adds a new dimension to crop trades and provides a new way of thinking about water scarcity. A systematic analysis of virtual water flows requires integration of all critical drivers of virtual water flows under a single consistent framework. The aim of this study was to assess virtual water flows related to trades of grain crops (wheat, corn, rice, and coarse cereals) and their influencing factors in Hetao irrigation district, China during 1981-2010. Results indicated that: (1) volume of virtual water export decreased from 2.08×10⁹ m³ in 1981 to 1.27×10⁹ m³ in 2010. Volume of virtual water import fluctuated around 621.48×10⁶ m³ during study period; (2) Cultivated area per capita and total population were the major influencing factors for virtual water export in Hetao irrigation district. Volume of virtual water import was mainly influenced by consumption and retail price index of grain crops. Combination of large volume of virtual water export and severely constrained water resources confronted Hetao irrigation district with great challenges in its sustainable development. Decreasing virtual water export is a mean to alleviate regional water shortage pressure, and may be achieved by measures that constrain continued population expansion.

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Waterlogging and drought are severe constrains that limit maize seedling growth in tropical and subtropical regions. It is significant to determine the differences in morphological and physiological responses of maize to drought and excess soil water, with a view toward better breeding and field management. In the present experiment, different levels of soil water availability were initiated at the one-leaf (V1) stage of two maize cultivars (Denghai9 and Yidan629): Control (CK), Severe Drought (SD), Light Drought (LD), Severe Waterlogging (SW), and Light Waterlogging (LW). The results indicated that waterlogging had more discernible impact on the seedling growth of both cultivars than drought stress. The Relative Growth Rate (RGR) of shoots and roots, along with root length, volume, and surface area were all markedly decreased in both cultivars under waterlogging stress. The malondialdehyde content increased significantly in roots and leaves under waterlogging treatment. In both cultivars, SuperOxide Dismutase (SOD) was mostly activated in roots and leaves at the three-leaf (V3) stage by waterlogging stress, while the Catalase (CAT) activity apparently increased under drought stress. The activity of Peroxidase (POD) distinctly enhanced in both cultivars under drought and waterlogging stress. Ascorbate Peroxidase (APX) showed constant activity with prolongation of waterlogging stress, and Glutathione Reductase (GR) activity notably increased in roots under waterlogging conditions at the six-leaf (V6) stage. We concluded that SOD, POD, APX, and GR were the most important antioxidant enzymes under waterlogging conditions, whereas CAT and POD appeared to play key roles under drought stress.

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Scientific measurement of Agricultural Carbon Emissions (ACE) and its formation mechanism is of great significance for the effective formulation of high-quality agricultural development strategies. Therefore, the objectives were to study the characteristics of ACE, its formation mechanism, and its economic relevance in Chongqing by adopting the IPCC and 1997-2019 data, and with LMDI index and Decoupling index. The empirical analysis shows that the total ACE presents an M-shaped trend of "rising-steady fluctuation-falling". Energy structure, energy intensity, and population size have a negative driving effect on ACE, but economic activity is the main factor. The decoupling elasticity characteristics of ACE and economic growth are mainly weak decoupling and strong decoupling, of which the relationship is significantly coordinate. Therefore, to consolidate and enhance the goal of ACE reduction, it is necessary to strengthen the research and development of agricultural low-carbon production technology and promotion. We will continue to deepen supply-side structural reform in agriculture. We will improve the ecological environment in agriculture and rural areas.