Tobacco, a pivotal economic crop in China, faces the challenge of securing high-quality raw materials for its industry due to unbalanced and inefficient nitrogen (N) application. To assess the impact of fertilizer management and soil factors on the yield and quality of flue-cured tobacco (FCT), a meta-analysis was conducted across 82 peer-reviewed research studies. The findings demonstrated that both fertilizer management and soil properties exerted a significantly greater influence on yield (63.13% and 62.05%, respectively) than the proportion of superior and medium tobacco (PSMT) (23.57% and 23.83%, respectively). Multiple models were conducted to analyze the N application rate for maximum yield and PSMT, respectively, resulting in an optimum range from 90 to 100 kg N ha⁻¹. The highest yield and PSMT increments were observed with fertilizer timing (FT) applied twice, a basal fertilizer ratio (BFR) exceeding 50%, and a soil pH below 6.5. The nicotine content escalated with increasing N application rates (NR) and soil nitrogen content, peaking at NR over 120 kg N ha⁻¹ and soil total nitrogen (TN) above 2 g kg⁻¹. Stepwise regression modeling indicated that nicotine content was positively influenced by fertilizer management factors (including NR, fertilizer timing, and BFR), as well as initial soil nitrogen content (AN and TN). However, it was negatively correlated with available potassium (AK). Therefore, the results of this meta-analysis suggest that effective fertilizer management, slightly acidic soils enriched with AK, and lower N supply capacity are crucial for enhancing leaf quality while reducing nicotine content. This approach promises improved economic and environmental returns for the tobacco industry in China.

This study was designed to investigate the relationship between the caloric value and salt tolerance of two varieties of Miscanthus sacchariflorus (Amur silvergrass: M127 and M022). The salt tolerance capacity, photosynthetic characteristics, Na⁺ and K⁺ uptake by the roots and aboveground parts, and caloric value of different parts of the aboveground parts were obtained under hydroponic conditions. The results showed that M022 was more tolerant to salt stress than M127 and the former had a higher photosynthetic efficiency as well as a lower aboveground Na⁺ accumulation, K⁺ efflux, and larger K⁺/Na⁺ ratio. The calorific values of stems, spear leaves, aging leaves, and functional leaves of the two varieties showed a decreasing trend with increasing NaCl concentration. At 270 mM NaCl, the calorific values of the stems, aging leaves, functional leaves, and spear leaves was reduced by 18.10%, 46.73%, 26.11%, and 18.35% for M022 and 41.99%, 39.41%, 34.82%, and 45.09% for M127 compared to the controls, respectively. We observed that the aging leaves of M022 had a faster decline rate in calorific value than those of M127, indicating that the aging leaves of M022 preferentially isolated the harmful Na⁺ ion, reduced its accumulation in other parts, and increased the K⁺/Na⁺ ratio in the corresponding parts, thus inhibiting the decrease in calorific value. Following this result, it can be inferred that M022 inhibited the decline in calorific values during stress by efficiently compartmentalizing the distribution of Na⁺ and K⁺. Our results provide a theoretical basis and technical support for the efficient cultivation of salt-tolerant energy plants in saline–alkaline soil.

Stenotaphrum secundatum is an excellent shade-tolerant warm-season turfgrass. Its poor cold resistance severely limits its promotion and application in temperate regions. Mining cold resistance genes is highly important for the cultivation of cold-resistant Stenotaphrum secundatum. Although there have been many reports on the role of the Shaker potassium channel family under abiotic stress, such as drought and salt stress, there is still a lack of research on their role in cold resistance. In this study, the transcriptome database of Stenotaphrum secundatum was aligned with the whole genome of Setaria italica, and eight members of the Shaker potassium channel family in Stenotaphrum secundatum were identified and named SsKAT1.1, SsKAT1.2, SsKAT2.1, SsKAT2.2, SsAKT1.1, SsAKT2.1, SsAKT2.2, and SsKOR1. The KAT3-like gene, KOR2 homologous gene, and part of the AKT-type weakly inwardly rectifying channel have not been identified in the Stenotaphrum secundatum transcriptome database. A bioinformatics analysis revealed that the potassium channels of Stenotaphrum secundatum are highly conserved in terms of protein structure but have more homologous members in the same group than those of other species. Among the three species of Oryza sativa, Arabidopsis thaliana, and Setaria italica, the potassium channel of Stenotaphrum secundatum is more closely related to the potassium channel of Setaria italica, which is consistent with the taxonomic results of these species belonging to Paniceae. Subcellular location experiments demonstrate that SsKAT1.1 is a plasma membrane protein. The expression of SsKAT1.1 reversed the growth defect of the potassium absorption-deficient yeast strain R5421 under a low potassium supply, indicating that SsKAT1.1 is a functional potassium channel. The transformation of SsKAT1.1 into the cold-sensitive yeast strain INVSC1 increased the cold resistance of the yeast, indicating that SsKAT1.1 confers cold resistance. The transformation of SsKAT1.1 into the salt-sensitive yeast strain G19 increased the resistance of yeast to salt, indicating that SsKAT1.1 is involved in salt tolerance. These results suggest that the manipulation of SsKAT1.1 will improve the cold and salt stress resistance of Stenotaphrum secundatum.

The persistence of cadmium (Cd) immobilization in acidic paddy soils is exacerbated by acidification and fluctuating redox conditions that promote Cd re-mobilization. While biochar is a promising amendment, its long-term efficacy in Cd immobilization relative to conventional lime and the underlying mechanisms remain incompletely resolved. This study tested the hypothesis that biochar’s superior effect lies in its durable enhancement of soil pH buffering capacity (pHBC), not merely in increasing initial pH. Using six acidic paddy soils amended with three biochars (corn straw, peanut straw, and seeded sunflower plate) and pH-matched lime [Ca(OH)₂] controls, we quantified pHBC changes, resistance to simulated acidification, and Cd dynamics during a flooding-drying cycle. Results showed that biochar amendments increased pHBC by 24.7–110%, significantly more than lime. Under acid stress, biochar-treated soils maintained higher pH and released 40–85% less soluble and extractable Cd than lime controls at equivalent pH range. Correlation and regression analyses established that the biochar-induced change in pHBC (ΔpHBC) was the strongest predictor of reduced Cd availability, exerting twice the influence of native soil pHBC. During the redox cycle, enhanced pHBC directly attenuated soil re-acidification upon drainage, minimizing Cd re-mobilization. Thus, the durable enhancement of soil pHBC is the central mechanism for biochar’s sustained Cd immobilization, advocating a strategic shift from transient pH adjustment to building inherent soil buffering resilience for long-term remediation security.

Biochar is widely recognized for its ability to immobilize heavy metals in soil, yet its direct effect on plant physiological metal-sequestration capacity remains poorly understood. This study explores a critical distinction between two mechanisms: direct, concurrent metal immobilization by biochar versus its capacity to physiologically precondition plants, altering their inherent metal uptake and distribution. Using a hydroponic design with pH-matched controls, the latter was isolated by preconditioning rice plants with peanut straw biochar (PSB) or corn straw biochar (CSB) and subsequently removing amendments before cadmium (Cd) exposure. Our results reveal that biochar (PSB) preconditioning may modify root architecture and surface chemistry, enhancing negative zeta potential and functional group density. This modification increased root Cd adsorption capacity by 50.1% and 142.7% within 2 h or 2.2% and 52.6% within 48 h compared to the normal and pH-adjusted controls, respectively, with shifted metal speciation toward stable complexes. However, this enhanced root sequestration coincided with an increased translocation factor, elevating shoot Cd content by 78% compared to the normal control. In contrast, CSB preconditioning showed negligible effects. Our findings suggest that biochar’s net impact on metal distribution is probably the product of two temporally distinct processes: chemical immobilization in growth media versus physiological preconditioning effects. This dual mechanism framework may explain the variability in literature reports on the effect of biochar on heavy metal uptake by plants. It also highlights the need for holistic biochar risk assessment that considers both chemical and plant physiological pathways in both soil and hydroponic systems.