The purpose of this study was to identify the fractal dimension and their relationships with alkalinity properties of soils, and to evaluate the potential of fractal dimension as an indicator of alkalinity properties of soil. Six soils with an increasing salinity (electrical conductivity was 0.09, 0.18, 0.62, 0.78, 1.57 and 1.99 dS m⁻¹, respectively) were selected from the western part of the Songnen Plain (China). Salt content, exchangeable sodium percentage, sodium adsorption ratio and other properties of the soils were determined and the soil particle-size distribution (0–2000 μm) was measured using a laser diffraction particle size analyser. Our results show that the overall fractal dimension of the selected soils ranged from 2.35 to 2.60. A linear regression analysis showed a significant negative correlation between fractal dimension and the amount of coarse sand and fine sand (r = − 0.5452, P < 0.05 and r = − 0.8641, P < 0.01, respectively), and a significant positive correlation with silt and clay (r = 0.9726, P < 0.01 and r = 0.9526, P < 0.01, respectively). Thus, soils with higher silt and clay content have higher fractal dimension values. Strong linear relationships between fractal dimension and salt content (P < 0.05), in particular a very significant positive relationship with HCO₃⁻ (P < 0.01), also exist. It is therefore possible to conclude that a soil’s fractal dimension could serve as a potential indicator of soil alkalization and the variability in alkaline soil texture.

A need is growing to plant superior Korean pine (Pinus koraiensis Siebold & Zucc.) seedlings to cope with the degradation of secondary forests in Northeast Eurasia. The goal of this study was to detect the physiological effect on the quality of Korean pine seedlings exposed to a range of spectra. One-year-old seedlings (n = 6) were cultured in three light-emitting diode (LED) spectra (69‒77 μmol m⁻² s⁻¹) of 13.9% red (R) + 77.0% green (G) + 9.2% blue (B) (R1BG5), 26.2% R + 70.2% G + 3.5% B (R2BG3), and 42.3% R + 57.3% G + 0.4% B (R3BG1). The spectrum of high-pressure sodium (HPS) lamps (43.9% R + 54.7% G + 1.5 B) was taken as the reference. Results showed that LED-lighting resulted in shorter seedlings with a greater diameter, shoot biomass, assessed quality, and sturdiness compared to those under the HPS-lighting. The R3BG1 spectrum reduced the shoot nitrogen (N) deficiency induced by the HPS spectrum, while the R1BG5 treatment induced a steady-state uptake of N and phosphorus (P) in whole-plant organs. The R1BG5 spectrum also resulted in a higher soluble sugar concentration and higher activities of glutamine synthetase and acid phosphatase in needles compared to the control. Seedlings in the R2BG3 spectrum had the highest concentrations of chlorophyll and soluble protein in the leaves. Overall, the R-high LED-spectrum could stimulate biomass accumulation in shoot, but meanwhile resulted in a P deficiency. Hence, the LED lighting in the R1BG5 spectrum is recommended to promote the quality of Korean pine seedlings.

Biochar and nitrogen fertilizers are known to increase soil carbon storage and reduce soil nitrogen loss as amendments, suggesting a promising strategy for highly effectively increasing soil productivity. However, few studies have explored the mechanisms of their effects on crop yield in terms of active carbon fraction and enzyme activity, which ultimately limits the potential for the application of biochar in combination with nitrogen fertilizers. To evaluate the effect of biochar and nitrogen fertilizer on the improvement of black soils in northeast China, a field experiment was conducted in the black soil to compare and analyze the application methods on total organic carbon (TOC), total nitrogen (TN), enzyme activities, and maize yields. Biochar rates: CK, C1, C2, and C3 (0, 9.8, 19.6, and 29.4 Mg·ha⁻¹); N fertilizer rates: N1/2 and N (30 and 60 kg·ha⁻¹). Results indicated that biochar and N fertilizer amendments significantly ameliorated soil fertility, such as TOC and TN, compared to the unamended soil. The TOC levels in the C3 treatment increased by 35.18% and the TN levels by 23.95%. The improvement in TN is more significant when biochar is blended with N fertilizer. Biochar blended with N fertilizer increased maize cellulase, urease, and invertase activities by an average of 53.12%, 58.13%, and 16.54%, respectively. Redundancy analysis showed that TOC, TN, and MBN contributed 42%, 16.2%, and 22.2%, respectively, to the maize yield indicator. Principal component analysis showed that reduced N fertilizer was more effective in improving yields, with a maximum yield increase of 50.74%. Biochar blended with N fertilizer is an effective strategy to improve the fertility and productivity of black soils in northeast China, while nitrogen fertilizer reduction is feasible and necessary for maintaining grain yield.

MADS-box genes are classified into five categories: ABCDE, including SEP1, SEP2, SEP3, SEP4, and other homologous genes, which play important roles in floral organ development. In this study, the cDNA sequence of the HrSEP1 gene was cloned by RT-PCR and confirmed that this gene belongs to the MADS-box gene family. In addition, subcellular localization experiments showed that the HrSEP1 protein was localized in the nucleus. We verified the interaction of HrSEP1 with HrSOC1, HrSVP, and HrAP1 using yeast two-hybrid and bimolecular fluorescence complementation assays. These genes jointly regulate the growth and development of floral organs. We also found a strong synergy between HrSEP1 and AP1 genes in sepals, petals, and stamens by transgenic methods and fluorescence quantitative PCR, suggesting that HrSEP1 and AP1 may co-regulate the development of these structures. In conclusion, the expression of HrSEP1 has a certain effect on the development of floral organs, and these findings lay the foundation for further research on the biological functions of MADS transcription factors in Hippophae rhamnoides.

Managing carbon input from crop straw in cropland ecosystems could increase soil organic carbon (SOC) sequestration to achieve C neutrality and mitigate climate change. The complexity of the chemical structures of crop residue largely affects SOC sequestration. Fungi communities play an important role in the degradation of crop residues. However, the relationship between the fungal community composition and the chemical structures of crop residues remains unclear and requires further investigation. Therefore, a 120-day incubation experiment was conducted in Mollisols in Northeast China to investigate the decomposition processes and dynamics of maize straw stem (ST), leaf (LE) and sheath (SH) residues using ¹³C-NMR spectroscopy. Additionally, the microbiomes associated with these residues were analyzed through high-throughput sequencing to explore their relationship. Our results showed that the alkyl C contents in all treatments exhibited increases ranging from 15.1% to 49.1%, while the O-alkyl C contents decreased, ranging from 0.02% to 11.2%, with the incubation time. The A/OA ratios of ST, LE and SH treatments were increased by 23.7%, 43.4% and 49.3% with incubation time, respectively. During the early stages of straw decomposition, Ascomycota dominated, and in the later stage, Basidiomycota were predominant. The class of Sordariomycetes played a key role in the chemistry transformation of straw tissues during decomposition. The keystone taxa abundances, Fusarium_kyushuense, and Striatibotrys_eucylindrospora, showed strong negative correlations with di-O-alkyl C and carbonyl-C content and positive correlations with the β-glucosidase and peroxidase enzyme activity, respectively. In conclusion, our study demonstrated that the keystone taxa play a significant role in regulating the chemical structures of straw tissues, providing a better understanding of the influence of residue quality on SOC sequestration.