Lime application is an effective measure for improving rice yield and alleviating soil acidity, whereas its long-term effects on the sequestration and stability of soil organic carbon (SOC) remain unclear in paddy fields. Here, we report on the first 10-year long-term experiment to examine the impact of lime application on the quantity and quality of SOC in an acidic paddy field with double rice cropping. Lime was applied every 4 years with and without rice straw incorporation. Size and density fractionation and solid-state ¹³C nuclear magnetic resonance spectroscopy were employed to examine the physical fractions and chemical composition of SOC, respectively. The results showed that lime application had no significant effect on either the total SOC concentration or stocks. Compared to the non-lime control, lime application led to a 60.0% decrease in the free particulate organic carbon (fPOC) concentration but a significant 17.9% increase in the concentration of occluded particulate organic carbon (oPOC) while reducing the concentration of mineral-associated organic carbon (MAOC) by 5.3%. Chemical composition analyses revealed a 5.1% reduction in the content of alkyl carbon (C) and a 6.8% decrease in the ratio of Alkyl C to O-Alkyl C. Lime application and straw retention had a significant interactive effect on the composition of SOC. Under straw removal, lime application increased the oPOC concentration by 56.6%, while no significant effect was observed under straw return. Lime application had no significant effect on the MAOC concentration under straw removal, whereas it reduced this concentration by 9.8% under straw return. Under straw removal, lime application reduced the proportion of Alkyl C by 9.5%, while no significant effect was observed under straw return. Therefore, we conclude that although the total SOC stocks are not altered, long-term lime application reduces the content of MAOC and Alkyl C in the acidic paddy soil, suggesting that long-term liming may reduce SOC stability.

Although numerous studies have evaluated the effects of agronomic practices on either rice yield or grain quality, a comprehensive assessment of potential synergies and trade-offs between these traits across multiple management strategies remains limited, which is of great importance to simultaneously improving rice yield and quality in the future. In the present study, a meta-analysis was conducted with paired observations of rice yield and quality when various agronomic practices, including altering sowing date, alternate wetting and drying, growth regulator application, nitrogen application, potassium application, organic fertilizer application, increased planting density, silicon application, variety selection and zinc application, are employed. We found that applications of growth regulator and potassium fertilizer can improve rice yield, milling and appearance quality simultaneously. Enhanced rice yield and milling quality can be achieved through variety selection and organic fertilizer application. Additionally, enhanced rice yield and appearance quality can also be achieved through silicon application. However, though increased planting density and altered sowing date can improve rice yield and milling quality, they cause lower appearance quality. By contrast, though nitrogen application can improve rice yield and milling quality, it comes at the expense of appearance and eating quality. Therefore, our results indicate that there are indeed complex synergistic relationships and trade-offs between rice yield and various aspects of grain quality. Integrated agronomic technique packages should be employed to simultaneously improve rice yield and grain quality in the future.

Tea quality is primarily determined by the accumulation of specialized metabolites in fresh leaves; however, the mechanisms by which propagation methods influence tea quality through plant–soil–microbiome interactions remain poorly understood. Here, sexually propagated (SR) and asexually propagated (AR) tea plants were comparatively investigated by integrating soil physicochemical analyses, leaf physiological assessments, widely targeted metabolomics, and rhizosphere metagenomic profiling. Compared with AR, SR significantly improved soil nutrient availability, characterized by higher soil organic matter, nitrogen, and phosphorus contents, and promoted the accumulation of key quality-related components, including tea polyphenols and soluble sugars. In particular, tea polyphenol content increased by 58.8%, while available phosphorus increased by 161.5% under SR conditions. SR also exhibited enhanced antioxidant capacity, as evidenced by elevated superoxide dismutase, peroxidase, and indole-3-acetic acid oxidase activities while maintaining hydrogen peroxide homeostasis. Metabolomic analysis revealed distinct metabolic reprogramming between propagation types, with differential metabolites significantly enriched in flavonoid biosynthesis, phenolic acid metabolism, caffeine metabolism, and α-linolenic acid metabolism pathways. Concurrently, metagenomic analyses demonstrated that SR reshaped rhizosphere microbial communities by enriching Actinomycetota, Pseudomonadota, and Planctomycetota and altering microbial functional profiles associated with central carbon metabolism, including glycolysis and the tricarboxylic acid cycle. Integrated microbiome–metabolome analyses further revealed strong positive associations between SR-enriched microbial taxa and quality-related metabolites, particularly flavonoids and phenolic acids, suggesting a close coupling between rhizosphere microbial functions and leaf metabolic reprogramming. Collectively, our findings demonstrate that propagation method acts as an important driver of tea quality formation by coordinating soil nutrient availability, rhizosphere microbial carbon-cycling functions, plant physiological regulation, and metabolite accumulation. This study provides multi-omics evidence for a soil–microbiota–metabolome coupling mechanism underlying propagation method-dependent tea quality formation and highlights the potential of sexual propagation as a strategy for producing high-quality tea.

Tea quality is largely determined by the accumulation of specialized metabolites in fresh leaves, yet the effects of the propagation method on tea quality and its belowground ecological basis remain insufficiently understood. In this study, sexually propagated (SR) and asexually propagated (AR) tea plants were compared by integrating soil physicochemical analysis, leaf quality and physiological measurements, widely targeted metabolomics, and rhizosphere metagenomic profiling. Compared with AR, SR plants exhibited more favorable rhizosphere nutrient conditions, with soil organic matter, total nitrogen, alkali-hydrolyzable nitrogen, and available phosphorus increasing by 23.1%, 18.2%, 27.8%, and 161.5%, respectively, although available potassium decreased by 24.4%. SR leaves also contained higher dry matter, tea polyphenol, and soluble sugar contents, which increased by 11.5%, 58.8%, and 8.6%, respectively. In addition, superoxide dismutase, peroxidase, and indole-3-acetic acid oxidase activities were 30.4%, 92.0%, and 21.7% higher under SR, whereas hydrogen peroxide content remained unchanged. Metabolomic profiling revealed marked differences in leaf metabolic composition between the two propagation types, with differentially accumulated metabolites mainly enriched in flavonoid biosynthesis, phenolic acid metabolism, caffeine metabolism, carotenoid biosynthesis, plant hormone signaling, and α-linolenic acid metabolism. Rhizosphere metagenomic analysis further showed that SR was characterized by higher relative abundances of Actinomycetota, Pseudomonadota, Planctomycetota, Alphaproteobacteria, and Streptomycetales, together with distinct microbial functional profiles related to glycolysis, the tricarboxylic acid cycle, and pyruvate metabolism. Significant correlations were identified between several SR-enriched microbial taxa and quality-related metabolites, particularly flavonoids and phenolic acids. Overall, under the present field conditions, sexual propagation was more favorable than asexual propagation for tea quality formation, as reflected by improved nitrogen and phosphorus availability, greater accumulation of quality-related metabolites, higher antioxidant enzyme activities, and distinct rhizosphere microbial carbon-metabolic potential. These findings provide an integrated soil–microbiome–metabolome perspective for understanding propagation-related differences in tea quality.