Bone meal has been used as economic and effective additive for heavy metals (HMs) pollution remediation due to the distinct components and structures that enable their favorable properties, such as its low cost, high adsorption capacity, acid-base adjustability, and ion-exchange capability. However, no attempt has been made to establish whether cow bone could promote the passivation of HMs and the removal of metal resistance genes (MRGs) and antibiotics resistance genes (ARGs) during the composting process. Two sizes of cow bone (meal (T2) and granule (T3)) were added to investigate their effects on humification, HMs passivation and the abundance of ARGs and MRGs during swine manure composting. Excitation-emission matrix (EEM)-parallel factor analysis showed that the percentage of maximum fluorescence intensity of humic-like substances were higher in T2 (91.82%) than in T3 (88.46%), implying that T2 could promote the humification process compared to T3. In comparison with control (T1), the addition of T2 and T3 could promote the change of exchangeable Cu and reducible Cu into oxidizable Cu, thus reducing the mobility factors (MF) of Cu in T2 and T3 treatments by 10.48% and 6.98%, respectively. In addition, T2 and T3 could increase exchangeable Zn into reducible Zn and oxidizable Zn, thereby reducing the MF of Zn in T2 and T3 treatments by 18.80% and 2.0%, respectively. Quantitative Real-time PCR (qPCR) analysis revealed that the total abundances of MRGs were decreased by 100% in T2 and T3 treatments, and T2 decreased the total relative abundance of ARGs. Furthermore, the relative abundance of ARGs and MRGs had significantly correlated with intI1 and bio-available of Cu and Zn, which was triggered by selective pressure of HMs and horizontal gene transfer. The present study suggested that cow bone meal as additives can be a feasible approach to promote the passivation of HMs and enhance the removal of MGRs and ARGs by decreasing horizontal gene transfer and selective pressure by bioavailable HMs.

Yellow pitaya (Hylocereus megalanthus) is highly photosensitive and therefore strongly influenced by light availability. In winter, insufficient sunlight often induces a “yin–yang effect”, characterized by physiological disparities between the sunlit and shaded sides of east–west-oriented orchards. To elucidate the effects of supplemental lighting parameters on flowering, yield, and fruit quality of shade-grown yellow pitaya, we systematically examined four factors: lighting angle (45°, 60°, 90°), power (12, 15, and 18 W), duration (3, 4, and 5 h per day), and lighting period (10, 20, and 30 days). Compared with no supplemental lighting (net photosynthetic rate = 10.60/11.73 μmol m⁻² s⁻¹, yield = 903/3536.5 kg ha⁻¹, net profit = 6435/72,675 CNY ha⁻¹ in two seasons), a 90° angle in the first season and a 60° angle in the second season increased the net photosynthetic rate by 45.87% and 60%, yield by 165.98% and 145.16%, and net profit by 373.82% and 159.42%, respectively. 18 W lighting power raised average yield and net profit by 176.37% and 278.7%, while 5 h lighting duration enhanced them by 161.29% and 267.66%. Meanwhile, a 20-day lighting period increased yield and profit by 128.91% and 240.6% on average. The recommended parameter set of a 60°/90° angle, 18 W power, 5 h duration, and 20-day lighting period markedly improved photosynthetic performance, yield, and net economic returns of shaded-side yellow pitaya. These improvements were attributed to enhanced carbon assimilation and reallocation from source to sink tissues, which contributed to higher fruit yield and quality and effectively mitigated winter shading stress.

Pineapple is widely cultivated in tropical regions, but intensive management and improper residue disposal can accelerate soil degradation and yield decline. To evaluate under-ridge residue burial (URRB) as a soil improvement practice, parallel field experiments were conducted from 2023 to 2024 at two sites in tropical southern China. A two-factor randomized complete block design was used, with two burial rates (half- and full-rate, i.e., 10 and 20 t ha⁻¹) and three burial depths (10, 20, and 30 cm), plus a residue removal control (CK). Compared with CK, URRB generally increased soil pH and the stocks of soil organic carbon and available nitrogen (N), phosphorus (P), and potassium (K), accompanied by higher leaf area index (LAI), total root surface area (TRSA), photosynthetic pigment contents, fruit vitamin C content, and plant N, P, and K accumulation. Increasing burial rate significantly enhanced plant P and K accumulation and fruit yield, while burial at 30 cm produced greater improvements in soil pH, soil organic carbon (SOC), and available N, P, and K stocks than burial at 10 cm and 20 cm. Compared with other treatments, full-rate residue burial at 30 cm depth under the ridge (FD30) most effectively promoted canopy growth, root development, fruit yield, and chlorophyll a content. On average across the two sites, FD30 increased LAI and TRSA by 20.9% and 34.0%, respectively, compared with CK, with significant increases of 20.1% in fruit yield and 25.3% in fruit vitamin C content. Partial least squares path modeling identified positive indirect associations of soil pH and nutrient availability with yield. Although pineapple yield did not differ significantly between FD30 and FD10, SOC, available N, P, and K stocks were significantly greater under FD30 than under FD10. Thus, FD30 is a more promising strategy for improving both soil fertility and pineapple production under the present experimental conditions. This study also provides new insights into crop residue management in tropical cultivation systems.