Adjusting agronomic measures to alleviate the kernel position effect in maize is important for ensuring high yields.  In order to clarify whether the combined application of organic fertilizer and chemical fertilizer (CAOFCF) can alleviate the kernel position effect of summer maize, field experiments were conducted during the 2019 and 2020 growing seasons, and five treatments were assessed: CF, 100% chemical fertilizer; OFCF1, 15% organic fertilizer+85% chemical fertilizer; OFCF2, 30% organic fertilizer+70% chemical fertilizer; OFCF3, 45% organic fertilizer+55% chemical fertilizer; and OFCF4, 60% organic fertilizer+40% chemical fertilizer.  Compared with the CF treatment, the OFCF1 and OFCF2 treatments significantly alleviated the kernel position effect by increasing the weight ratio of inferior kernels to superior kernels and reducing the weight gap between the superior and inferior kernels.  These effects were largely due to the improved filling and starch accumulation of inferior kernels.  However, there were no obvious differences in the kernel position effect among plants treated with CF, OFCF3, or OFCF4 in most cases.  Leaf area indexes, post-silking photosynthetic rates, and net assimilation rates were higher in plants treated with OFCF1 or OFCF2 than in those treated with CF, reflecting an enhanced photosynthetic capacity and improved post-silking dry matter accumulation (DMA) in the plants treated with OFCF1 or OFCF2.  Compared with the CF treatment, the OFCF1 and OFCF2 treatments increased post-silking N uptake by 66.3 and 75.5%, respectively, which was the major factor driving post-silking photosynthetic capacity and DMA.  Moreover, the increases in root DMA and zeatin riboside content observed following the OFCF1 and OFCF2 treatments resulted in reduced root senescence, which is associated with an increased post-silking N uptake.  Analyses showed that post-silking N uptake, DMA, and grain yield in summer maize were negatively correlated with the kernel position effect.  In conclusion, the combined application of 15–30% organic fertilizer and 70–85% chemical fertilizer alleviated the kernel position effect in summer maize by improving post-silking N uptake and DMA.  These results provide new insights into how CAOFCF can be used to improve maize productivity.

Rice false smut, caused by Ustilaginoidea virens, is a devastating disease that greatly reduces rice yield and quality.  However, controlling rice false smut disease is challenging due to the unique infection mode of U. virens.  Therefore, there is a need for early diagnosis and monitoring techniques to prevent the spread of this disease.  Lateral flow strip-based recombinase polymerase amplification (LF-RPA) overcomes the limitations of current U. virens detection technologies, which are time-consuming, require delicate equipment, and have a high false-positive rate.  In this study, we used a comparative genomics approach to identify Uv_3611, a specific gene of U. virens, as the target for the LF-RPA assay.  The designed primers and probe efffectively detected the genomic DNA (gDNA) of U. virens and demonstrated no cross-reactivity with related pathogens.  Under optimal conditions, the LF-RPA assay demonstrated a sensitivity of 10 pg of U. virens gDNA.  Additionally, by incorporating a simplified PEG-NaOH method for plant DNA extraction, the LF-RPA assay enabled the detection of U. virens in rice spikelets within 30 min, without the need for specialized equipment.  Furthermore, the LF-RPA assay successfully detected U. virens in naturally infected rice and seed samples in the field.  Therefore, the LF-RPA assay is sensitive, efficient, and convenient, and could be developed as a kit for monitoring rice false smut disease in the field.

Intensified kernel position effect is a common phenomenon in maize production under higher plant density, which limits the crop productivity.  Subsoiling is considered as an effective agronomic practice to improve crop productivity.  In order to clarify the effect of subsoiling before winter wheat on kernel position effect of densely grown summer maize and its regulatory mechanism, field experiments were conducted during 2020-2021 and 2021-2022 growing seasons by using a split-plot design.  Main plot include two tillage practices: conventional tillage practice (CT) and subsoiling before winter wheat (SS); subplot consist three plant densities (D1-D3, 6.0×10⁴, 7.5×10⁴, and D3, 9.0×10⁴ plants ha^-1).  Compared with CT, SS alleviated the kernel position effect by increasing the weight ratio of inferior to superior kernel (WR) of D2 and D3 treated plants.  The higher WR of SS treated plants attribute largely to the improved filling of inferior kernel.  Under the same plant density, SS significantly improved the root dry matter accumulation (DMA) and antioxidant enzyme activities (SOD and POD), and reduced malondialdehyde (MDA) concentration, especially for the plants grown under higher plant densities.  These result indicated that SS delayed the root senescence, which is associated with the reduced soil bulk density.  In addition, by comparison with CT, SS increased the leaf chlorophyll content from 20 days after silking to physiological maturity and post-silking leaf area duration, and decreased post-silking leaf chlorophyll reduction rate and leaf area reduction rate, reflecting the post-silking leaf senescence is alleviated.  Under the same plant density, the post-silking DMA of SS was obviously higher than that of CT, which is probably related to the improved leaf area duration and photosynthetic enzyme activity (PEPC and Rubisco).  The correlation analysis revealed that the main mechanism of SS in alleviating kernel position effect of densely grown summer maize is: SS delayed the post-silking root-shoot senescence by regulating soil physical properties, and further improved the post-silking DMA and filling of inferior kernel, ultimately alleviated the kernel position effect and improved grain yield.  The present result will provide a new theoretical support for the promotion of summer maize yield by subsoiling before winter wheat. 

Farmers in China often use nitrogen (N) fertilizers to ensure adequate crop growth. However, injudicious applications have increased the risk of environmental pollution, lower maize yields, and reduced profits for farmers.  Appropriate N fertilizer management is crucial for improving yield and nitrogen use efficiency (NUE). This study conducted a three-year experiment involving nine N treatments (0, 45, 90, 135, 180, 225, 270, 315, and 360 kg ha^-1) on a field under nitrogen fertilizer precision management (NFPM) in Northeast China.  These results were compared with studies published within the past decade that analyzed yield and dry matter (DM) content under two management practices in Northeast China: conventional nitrogen fertilization management (CNFM) and water-saving fertilization management (WSFM).  The findings reveal that maize yield increases with rising N application rates up to 270 kg ha^-1, after which yield decreases.  The kernel number (KN) and kernel weights (KW) of maize grown under NFPM were 13.7 and 14.7% higher than those grown under WSFM, respectively.  Furthermore, they surpassed crops grown under CNFM by 38.4 and 21.2%, respectively.  The maximum total yield of the NFPM treatment was 41.8 and 78.8% higher than WSFM and CNFM, respectively.  Additionally, compared with CNFM and WSFM, NFPM significantly increased nitrogen use efficiency (NUE) across various N-level treatments. Optimizing nitrogen management could help farmers achieve higher yields and promote sustainable agricultural development.

CRISPR/Cas9-based gene editing research has advanced greatly and shows broad potential for practical application in life sciences, but the Cas9 system is often constrained by the requirement of a protospacer adjacent motif (PAM) at the target site. While xCas9, a variant derived from Streptococcus pyogenes Cas9 (SpCas9), can recognize a broader range of PAMs, its application in non-model insects is lacking. In this study, we explored xCas9 activity in gene editing by selecting corazonin (Crz) and the target sites with various PAMs in Locusta migratoria, a destructive insect pest worldwide. We found that xCas9 could cleave the target site with AG PAM while SpCas9 could not, although xCas9 appeared to have lower activity than SpCas9 at the canonical NGG PAMs. The heritable homozygous Crz^-/- locust strain was generated by the application of xCas9. The Crz^-/- strain showed an albino body color, with significantly downregulated expression of several body color-related genes including Pale, Vermilion, Cinnabar, White and β-carotene-binding protein. In addition, Crz^-/- mutants exhibited significantly reduced expression of Chitin synthase 1, along with a markedly lower chitin content as well as compact and rigid cuticles. Furthermore, Crz^-/- mutants displayed impaired performance under low-temperature stress, including prolonged lifespan, reduced body weight and smaller body size. Our results suggest that xCas9 is effective for insect genome editing, and Crz plays essential roles in insect body color, cuticle development and adaptation to low-temperature stress. The findings of this study extend the application of xCas9 in non-model insects and provide new insights into our understanding of the regulation of insect cuticle development and environmental adaptation.