Single-time fertilization (STF) of controlled release blended fertilizer (CRBF) improves grain yield and nitrogen use efficiency (NUE) in rice production. However, the impact of soil nitrogen (N) distribution and root growth on rice yield and NUE under STF of CRBF remains unclear. This two-year field experiment investigated the effects of fertilizer types (normal urea (U) and CRBF) and single-time fertilization methods (broadcast and side-deep fertilization) on the soil N distribution, plant N uptake, root characteristics, grain yield and NUE. The results showed that CRBF under STF averaged increased plant dry matter accumulation, N uptake, grain yield, nitrogen recovery efficiency (NRE), and nitrogen agronomic efficiency (NAE) by 8.29, 21.85, 10.57, 79.28, and 74.8% compared to the other treatments, respectively. Side-deep fertilization of CRBF further increased NUE by 12.78% compared to broadcast. Moreover, CRBF under STF increased leaf SPAD value and glutamine synthetase (GS) /glutamine oxoglutarate aminotransferase (GOGAT) activity by 5.93 and 25.58%. CRBF under STF increased the soil inorganic N concentration and showed a “rising early and stabilizing later” characteristic. Additionally, CRBF under STF improved rice root growth and averaged increased root biomass, total root number, root average diameter, total root length, total root surface area, total root volume by 28.30, 28.56, 18.64, 13.38, 35.26, and 37.06% at tillering and heading stages, respectively. Partial least squares path modeling indicated that CRBF under STF increased soil inorganic N concentration to improve root morphology, thereby increasing N uptake and improving and rice yield and NUE. Taken together, our findings support that CRBF with single-time fertilization is the preferred N fertilizer strategy for achieving high yield and efficiency in rice and that side-deep fertilization is the optimal fertilization method.
African swine fever (ASF) is an acute, hemorrhagic disease caused by the African swine fever virus (ASFV), with a mortality up to 100%. The disease poses a seriously threat to the global swine industry, yet no commercial vaccines or antiviral drugs are available other than in Vietnam. ASFV attenuation through serial passages is a key approach for vaccine development. In this study, a cell-adapted virus, named HLJ18/BK33, was successfully generated by serially passaging the ASFV Pig/HLJ/18 in wild boar kidney cells (BK2258). This adapted virus exhibited clear cytopathic effects (CPE) and replicated stably and efficiently in BK2258 cells and porcine alveolar macrophages. Whole-genome sequence analysis revealed that, compared with the Pig/HLJ/18 virus, HLJ18/BK33 had a large deletion of 6162 bp from sites 181,027 to 187,188, and four single nucleotide deletions that led to frameshift mutations, resulting in the truncated expression of three open reading frames (ORFs) (ASFV_G_ACD_00120, ASFV_G_ACD_00350, and A179L), and the fusion expression of two ORFs (MGF_110-14L and MGF_110-11L). Additionally, four genes exhibited missense mutations, leading to single amino acid changes. Five pigs intramuscularly inoculated with 106 TCID50 of HLJ18/BK33 remained healthy with normal body temperatures and no clinical signs, indicating a high attenuation of virulence for HLJ18/BK33 in pigs. Upon challenge with the parental Pig/HLJ/18 virus, four of the five inoculated pigs developed persistent high fever and ASF-related clinical signs and died within 13 days of the challenge; the remaining pig developed transient fever but survived until the end of the observation period. These results indicate that the HLJ18/BK33 virus is highly attenuated but cannot induce protection against the parental virulent virus. Even though the HLJ18/BK33 virus is not a good vaccine candidate, its stable replication and distinct CPE in BK2258 cells as well as its low biosafety risk make it a valuable resource for studies on virus-host interactions, antiviral drug screening, diagnostic methods, and biological characteristics.