The effects of maize straw return and N fertilizer application on soil quality and crop yield have been extensively investigated.  However, the effects of different amounts of maize straw returned to the field with different nitrogen application rates on the soil–crop system quality, abundance of functional N cycle microorganisms, N₂O emissions, and crop N nutrition status of crops have not been thoroughly explored.  The objective of this study was to assess the effects of different summer maize straw return rates and N application rates on i) soil quality and crop productivity; ii) the community of N cycle functional microorganisms and N₂O emission; and iii) crop N status.  The results indicated that crop yields increased by 7.62 to 12.69% at 210 kg ha^–1 of N application for full straw return (SN) and half return (1/2SN) compared to the no-return treatment (CK).  No significant difference was noted in the yields between the full straw return reduced by 15% (178.5 kg N ha^–1) of N fertilizer (S-15%N) and SN.  The surface soil layer (0–20 cm) showed significantly higher levels of soil organic matter (SOM), the community of N-cycling functional microorganisms, crop N nutrition status and N uptake efficiency in SN, 1/2SN, and S-15%N as compared to other treatments.  Compared to SN, S-15%N and 1/2SN reduced cumulative N₂O emission fluxes by 19.11 and 5.51%, respectively.  Furthermore, the nitrogen nutrient index (NNI) values of 1/2SN and S-15%N were closer to the critical N requirement than SN.  In summary, schemes for determining the optimal rates of straw return and N application (1/2SN and S-15%N) based on SOM, NNI, cumulative N₂O emission fluxes, and yield can be applied to the annual production of winter wheat and summer maize in China.

Porcine reproductive and respiratory syndrome virus (PRRSV), the etiological agent of porcine reproductive and respiratory syndrome (PRRS), has caused substantial  economic losses to the global swine industry. In recent years, frequent genetic recombination and mutation events in PRRSV have given rise to numerous genetic  variants, presenting significant challenges for PRRS containment and eradication programs. In the present investigation, a novel PRRSV strain, designated FJNP22-1, was successfully isolated from an affected pig farm in Fujian Province, China, during a 2023 disease outbreak. Comprehensive phylogenetic analysis of the complete genome sequence identified FJNP22-1 as a member of Lineage 8 within the PRRSV-2. Notably, ORF5-based phylogenetic characterization revealed its classification within  Sub-lineage 1.8 of PRRSV-2. Genomic recombination analysis revealed that FJNP22-1 was a recombination strain derived from HP-PRRSV (Lineage 8, major parental strain) and NADC30-like (Lineage 1, minor parental strain), with seven distinct recombination breakpoints identified across Nsp2, Nsp3, ORF2, and ORF4 gene regions. Pathogenicity evaluation demonstrated that FJNP22-1 infection induced 100% morbidity in piglets, with clinical manifestations including pyrexia, anorexia and severe growth retardation. Necropsy findings confirmed marked pulmonary lesions, supporting the conclusion that FJNP22-1 exhibits high pathogenicity in swine. Furthermore, a novel recombinant PRRSV-vectored vaccine candidate (rPRRSV-E2), engineered via reverse genetics to express the classical swine fever virus (CSFV) E2 glycoprotein, conferred robust protection against FJNP22-1 challenge in piglets. This study enhances our understanding of PRRSV molecular epidemiology and provides valuable insights for vaccine development and PRRS control strategies in China.

High-density planting is a pivotal strategy for safeguarding food security, yet it is frequently accompanied by a pronounced escalation in lodging risk. This study aimed to elucidate how a spatially heterogeneous configuration mitigates lodging and stabilizes yield in wheat. Field experiments, together with machine-learning approaches and path modeling, were conducted to identify the key constraints underlying lodging resistance under contrasting planting configurations. Relative to the high-density homogeneous distribution (HD), the high-density heterogeneous distribution (HD-h) effectively alleviated within-canopy shading, thereby stabilizing the assimilate carbon flux delivered to the stem. This sustained carbon supply, in turn, enhanced the activity and transcriptional expression of key enzymes/genes involved in cellulose biosynthesis, promoting the development of mechanical tissues and increasing stem mechanical load-bearing capacity. Machine-learning further revealed a density-dependent shift in the primary limiting factors for lodging resistance: constraints transitioned from fluctuations in canopy light environment under lower resource pressure to a mechanically oriented bottleneck under high density, dominated by carbon metabolism and structural construction. By stabilizing source-derived carbon flux, HD-h coordinated the maintenance of high lodging resistance with concurrent support for spike number per unit area and individual-spike traits, thereby relaxing the conventional trade-off between yield and structural stability under dense planting. Optimizing spatial configuration improves lodging resistance and yield stability under high-density conditions by promoting assimilate conversion into structural carbon.