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Crop residue management is a major concern in China. Returning straw to the field has been promoted to reduce chemical fertilizer input and increase crop yield. For this, the present study as a part of an existing long-term field experiment was conducted including four treatments: (1) Maize straw return with reduced nitrogen, phosphorus, and potassium fertilizers (straw + NPK; SNPK); (2) NPK fertilizers; (3) PK fertilizers; and (4) no fertilizers added (nF) in the years of 2016 and 2017. Results showed SNPK and NPK produced similar grain yield over the two years (12,485 vs. 12,754 kg ha−1), which was approximately 3-fold of PK and nF (4763 vs. 3858 kg ha−1). The yield difference was not significant between SNPK and NPK and between PK and nF. The effect of straw return on plant productivity is related to precipitation. In contrast to total carbon (C), nitrogen (N), and phosphorus (P), K was lost from leaf, stem, and grain. Dynamics of plant N post-flowering is critical to determine maize yield and yield components relative to C, P, and K. Dynamics of P and K in leaf were more correlated with yield than in stem, implying the significance of leaf productivity in determining grain yield. These results indicate that combination of NPK fertilizers is critical for increasing grain yield in maize. Crop straw return with reduced NPK fertilizers will help to improve yield and reduce chemical fertilizer input in the long run.

Low temperature limits the photochemical efficiency of photosystems in wheat plants. To test the effect of salt priming on the photosynthetic electron transport in wheat under low temperature, the germinating seeds of a winter wheat cv. Jimai44 were primed with varying concentrations of NaCl solutions (0, 10, 30, and 50 mM NaCl, indicated by S0, S10, S30, and S50, respectively) for 6 d, and after 11 d of recovery, the seedlings were subsequently exposed to 24-h low-temperature stress (2 °C). Under low temperature, the S30 plants possessed the highest absorption flux per reaction center and higher density of reaction center per cross-section among the treatments. In addition, S30 plants had higher trapped energy flux for reducing QA and fraction of QA-reducing reaction centers and non-QB reducing center than the non-primed plants under low temperature, indicating that S30 plants could maintain the energy balance of photosystems and a relatively higher maximum quantum efficiency of photosystem II under low temperature. In addition, the low temperature-induced MDA accumulation and cell death were alleviated by salt priming in S30 plants. It was suggested that salt priming with an optimal concentration of NaCl solution (30 mM) during seed germination enhanced the photochemical efficiency of photosystems in wheat seedlings, which could be a potential approach to improve cold tolerance in wheat at an early stage.

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Aircraft is a typical transportation facility and its development need to refer to the existing knowledge. With the rapid increase of knowledge, a knowledge map may deliver excess knowledge to users that they cannot manage at once, thereby causing the problem of knowledge overload. Hence, a novel method for adaptive knowledge map construction was proposed to solve this problem. First, the knowledge was semantically annotated and stored with the domain ontology and a knowledge model that integrates context. Then, user requirement was described by the context of product design, and knowledge nodes that met users' requirement could be extracted from the knowledge retrieval technology on the basis of context similarity. Finally, the connection between knowledge nodes was constructed with a composite connection model, and the knowledge map was visualized using a hierarchical approach. To verify the effectiveness of the proposed method, the constructed knowledge map was applied in an airplane wing design to assist users in browsing the knowledge base. Results indicate that the proposed method can change the displayed contents according to user requirement and identify the displayed knowledge nodes at a highly acceptable level, the constructed knowledge map can guide users efficiently, and the knowledge overload can be reduced significantly.

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High yields and low carbon emissions are new challenges for modern crop production. Balancing the crop yield and reducing greenhouse gas (GHG) emissions has become a new field of agronomic technology innovation. Cereal–legume intercropping is a typical diversification planting system, which has been expected to achieve the dual goals of high production and low GHG emissions. However, the synergistic effect of integrating various technologies in an intercropping system on GHG emissions and whether it will achieve the high yield and low emissions goal remains to be determined. Therefore, bibliometric analysis has investigated the worldwide development trend of cereal–legume intercropping designs. The literature on the GHG emissions of the cereal–legume intercropping system was summarized. Additionally, the effects and mechanisms of different agricultural management methods regarding soil nitrous oxide and carbon dioxide emissions in the cereal–legume intercropping system were summarized. The research on GHG emissions of cereal–legume intercropping systems in non-growing seasons must be revised. In situ observations of GHG emissions from intercropping systems in different regions should be strengthened. This work is valuable in supporting and evaluating the potential of GHG reduction in a cereal–legume intercropping system in various farming areas.