Biochar application can enhance soil health and alter soil bacterial community structure. However, knowledge relating to biochar on soil nutrients of mountainous apple orchards and then assessing its effect on soil health, especially on soil microorganisms, is still scanty. Therefore, we evaluated the responses of six biochar treatments [Ck (0), T1 (2), T2 (4), T3 (6), T4 (8), and T5 (10) Mg hm⁻²] with a basal dose of chemical fertilizer on the soil nutrients under potted apple trees across 3, 6, 9, and 12 months, and then investigated the responses of the rhizobacterial communities. Experimental findings demonstrated that: (i) Across the months, the biochar-applied treatment (T5) compared to the control significantly enhanced soil nutrients, including soil pH (2.12 to 2.29%), soil organic matter (35 to 40%), total nitrogen (59 to 65%), ammonium nitrogen (25 to 33%), nitrate nitrogen (163 to 169%), and the activities of urease (76 to 81%), alkaline phosphatase (30 to 33%), catalase (8.89 to 11.70%), and sucrase (23 to 29%). (ii) Compared to the control, the biochar-applied treatment (T5) had a more desirable relative abundance of the bacterial phylum Proteobacteria (35.47%), followed by Actinobacteria (8.59%), Firmicutes (5.74%), and Bacteroidota (2.77%). Similarly, the relative abundance of the bacterial genera in the T5 was Sphingomonas (8.23%) followed by RB41 (3.81%), Ellin6055 (3.42%), Lachnospiracea (1.61%), Bacillus (1.43%), Kineosporia (1.37%), Massilia (0.84%), and Odoribacter (0.34%) than the control. (iii) Among the alpha diversity, the biochar-applied treatment (T5) revealed the highest Chao1 (20%) and ACE (19.23%) indexes, while Shannon (1.63%) and Simpson (1.02%) had relatively lower indexes than the control. Furthermore, positive correlations were found between the soil nutrients and some of the abundant bacterial phyla. Overall, the findings of this research demonstrated that biochar application at 10 Mg hm⁻² (T5) along with the required chemical fertilizer is beneficial to improve soil health and pave the way for sustainable production in apple orchards of the northern loess plateau.

The Loess Hilly–Gully region (LHGR) is the most serious soil erosion area in the world. For the small watershed with high management in this area, the scientific problem that has been paid attention to in recent years is the impact of the land consolidation project on the erosion environment in the gully region. In this study, the 3D simulation method of vegetation, eroded sediment and pollutant transport was innovated based on the principles of erosion sediment dynamics and similarity theory, and the impacts of GLCP were analyzed on the erosion environment at different scales. The verification results show that the design method and the scale conversion relationship (geometric scale: ${\mathsf{\lambda }}_{\mathrm{l}}$ = 100) were reasonable and could simulate the transport process on the complex underlying surface of a small watershed. Compared with untreated watersheds, a significant change was the current flood peak lagging behind the sediment peak. There were two important critical values of GLCP impact on the erosion environment. The erosion transport in HMSW had no change when the proportion was less than 0.85%, and increased obviously when it was greater than 3.3%. The above results have important theoretical and practical significance for watershed simulation and land-use management in HMSW.

Gully Land Consolidation (GLC) is a proven method to create farmlands and increase crop yields in the Loess Hilly and Gully Region, China. However, GLC influences phreatic water transformation and might cause the farmlands water disasters, such as salinization and swamping. For exploring the influence of GLC on phreatic water transformation and mitigating disasters, a series of indoor experiments were conducted in the artificial rainfall hall. Then, we simulated the phreatic water transformation patterns under more conditions with HYDRUS-3D. Finally, an engineering demonstration in the field was performed to validate our research. The indoor experiments indicated that GLC could increase phreatic water outflow rate 4.39 times and phreatic water coefficient (PWC) 2.86 times with a considerable delay. After calibration and validation with experimental data, the HYDRUS-3D was used to simulate phreatic water transformation under more soil thickness and rainfall intensities. Accordingly, we summarized the relationship among PWC, rainfall intensities, and soil thickness, and therefore suggested a blind ditch system to alleviate farmlands disasters. Field application showed that a blind ditch system could avoid disasters with 3.2 times the phreatic water transformation rate compared to loess. Our research provides implications for sustainable land uses and management in the region with thick soil covers.

Changes in the soil organic matter are related to the land-use change of sustainable agricultural production. However, few studies have been reported on the effects of changes in planting practices on SOC during the reconstruction period of old apple orchards. In this study, 4 treatments were applied during the reconstruction period of old apple orchards (more than 20 years old) on the Loess Plateau: thinning and replanted apple saplings (TR); all felled and planted corn (CR); all felled and planted millet (MT); all felled and planted potato (PT). It was found that: SOC was ranked as MT > PT > CR > TR, and decreased with soil depth, obeying the power function law; this first decreased and then increased, with the lowest ranking of the year being obtained in August in a year; MT was the most effective in increasing SOC, with an average annual growth rate of 0.54 g/(kg∙year). In this study, the complex relationship between rainfall, temperature, solar radiation, soil moisture content, and soil organic carbon was established. The results not only provide a reference for the reconstruction of old apple orchards, but also provide support for sustainable agricultural production in the fragile ecological zone of the Loess Plateau.

Abiotic stresses such as nitrogen deficiency, drought, and salinity significantly impact coconut production, yet the molecular mechanisms underlying coconut’s response to these stresses are poorly understood. MYB proteins, a large and diverse family of transcription factors (TF), play crucial roles in plant responses to various abiotic stresses, but their genome-wide characterization and functional roles in coconut have not been comprehensively explored. This study identified 214 CnMYB genes (39 1R–MYB, 171 R2R3–MYB, 2 3R–MYB, and 2 4R–MYB) in the coconut genome. Phylogenetic analysis revealed that these genes are unevenly distributed across the 16 chromosomes, with conserved consensus sequences, motifs, and gene structures within the same subgroups. Synteny analysis indicated that segmental duplication primarily drove CnMYB evolution in coconut, with low nonsynonymous/synonymous ratios suggesting strong purifying selection. The gene ontology (GO) annotation of protein sequences provided insights into the biological functions of the CnMYB gene family. CnMYB47/70/83/119/186 and CnMYB2/45/85/158/195 were identified as homologous genes linked to nitrogen deficiency, drought, and salinity stress through BLAST, highlighting the key role of CnMYB genes in abiotic stress tolerance. Quantitative analysis of PCR showed 10 CnMYB genes in leaves and petioles and found that the expression of CnMYB45/47/70/83/85/119/186 was higher in 3-month-old than one-year-old coconut, whereas CnMYB2/158/195 was higher in one-year-old coconut. Moreover, the expression of CnMYB70, CnMYB2, and CnMYB2/158 was high under nitrogen deficiency, drought, and salinity stress, respectively. The predicted secondary and tertiary structures of three key CnMYB proteins involved in abiotic stress revealed distinct inter-proteomic features. The predicted interaction between CnMYB2/158 and Hsp70 supports its role in coconut’s drought and salinity stress responses. These results expand our understanding of the relationships between the evolution and function of MYB genes, and provide valuable insights into the MYB gene family’s role in abiotic stress in coconut.

Viscosity is a fundamental hydrodynamic property of erosive flow, but except for the effect of sediment on viscosity, the effect of other erosive substances such as agricultural nitrogen on the characteristics of erosive flow has rarely been studied. This in turn is likely to be an important factor affecting the erosive transport mechanism. In this study, the effect of nitrogen on the viscosity of sediment-laden flow with different levels was investigated by using a self-made dual vertical tube rheometer. It was found that: (i) the viscosity coefficient (μ) of nitrogen-bearing erosive flow is affected by the nitrogen concentration, sediment content, and the physical and chemical properties of the sediment; (ii) the calculation model of the relative viscosity coefficient with the effects of nitrogen, concentration, sediment gradation, and temperature, was constructed, and the validation showed that the model not only has a clear physical meaning but also has a simple calculation method and good calculation accuracy. The results of the study are of great significance for the in-depth understanding of the erosion transport mechanism of erosive flow.