Agronomy

This study investigates the impact of tire wear particles (TWPs) and their dissolved organic matter (DOM) on soil DOM dynamics and heavy metal behavior. Through short-term incubation experiments under simulated natural conditions with TWPs of varying particle sizes, we analyzed ecological changes in soil. Using three-dimensional excitation–emission matrix (3D-EEM) spectroscopy coupled with parallel factor analysis, we monitored the photochemical properties and compositional evolution of soil dissolved organic matter. Results demonstrate that TWP amendment substantially alters soil DOM molecular characteristics, inducing a sharp decrease in protein-, carbohydrate-, and lipid-like components, the degradation of low-aromaticity unstable dissolved organic matter, and an overall increase in aromaticity. Furthermore, TWP input directly modified soil properties, triggering the transformation of soil aggregates: the proportion of large aggregates significantly decreased while that of small aggregates increased, thereby reducing overall aggregate stability. The bioaccessibility of heavy metals (HMs) (Cd, Cu, and Zn) extracted by CaCl₂ increased, primarily due to the release of endogenous metals from TWPs, compounded by the disruption of soil aggregates. In contrast, Pb tended to transform into more stable fractions under TWP stress, reducing its bioaccessibility. Further correlation analysis indicated that TWPs indirectly affected HM (Cd, Cu, and Zn) fractionation by influencing the soil dissolved organic matter properties and soil properties. This study provides a new perspective for elucidating the interplay between dissolved organic matter and HMs in urban soils, as mediated by tire wear particles (TWPs).

Branching traits play a critical role in shaping the tree structure of fruit crops and directly influence both yield and fruit quality. Effective and well-managed branching is crucial for maximizing productivity. However, loquat trees typically exhibit weak branching ability, characterized by fewer and longer bearing shoots, along with terminal flower buds, which collectively result in lower yields per unit area. Despite their significance, research on branching characteristics in loquat remains limited. To clarify the factors influencing branching and to provide a rational and effective direction for improving the inherently weak branching performance of current loquat cultivars, we selected the loquat varieties ‘Dawuxing’ and ‘Chunhua 1’, which exhibit significant differences in leaf and branch growth. Compared to ‘Dawuxing’, ‘Chunhua 1’ has longer branches, wider stem and leaf angles, fewer lateral branches, and a looser leaf cell structure. Transcriptome analysis of terminal buds at different developmental stages revealed that differentially expressed genes in the terminal buds of central branches from the spring and summer shoots of the two cultivars were enriched in the plant hormone signal transduction pathway. Hormone-targeted metabolomics identified significant differences in the levels of abscisic acid, auxins, cytokinins, gibberellins, jasmonic acid, and strigolactones in the terminal buds of both cultivars. Through integrated analysis, two candidate genes were identified as potential regulators of branching differences between the two cultivars: EVM0025028 (EjSAPK1), SnRK2 gene a core component of the abscisic acid signaling pathway, and EVM0040331 (EjRMS3), a D14 gene involved in encoding a strigolactone receptor. These findings provide valuable genetic resources for future research on branching regulation in Eriobotrya species and offer a theoretical foundation for enhancing branching management in loquat cultivation.

One of the main objectives of agriculture is to improve crop production and mitigate oxidative damage caused by climate change, such as water stress. This study evaluated the potential use of Klebsormidium sp. K39 extract (Kleb), obtained by phycoremediation treatment, to address these agricultural challenges. The experimental trials involved the application of Kleb at 1 mg C_org L⁻¹ through foliar spray, under standard or water stress (WS) conditions. The effect of Kleb was evaluated by monitoring growth parameters, antioxidant activities, and lipid peroxidation. The quality parameters of the tomato fruits were also evaluated. The results demonstrated that the application of Klebsormidium extract enhanced tomato growth while maintaining root development and canopy cover under water stress conditions. These findings suggest that Kleb may act as a biostimulant to improve crop resilience. Moreover, treated plants under water stress conditions had an increase in yield of around 35% with respect to untreated stressed plants. Although fruit quality parameters were not significantly affected, in Kleb-treated plants lycopene content increased only under standard conditions, while polyphenol content significantly increased under both WS and standard conditions. In treated plants, lipid peroxidation decreased by 58% in the leaves and 19% in the fruits under WS conditions, suggesting a significant reduction in oxidative damage. In the fruits, correlation analysis revealed positive relationships among key stress markers. These findings suggest that Kleb extract enhances resilience to water stress in tomato plants by modulating antioxidant responses and secondary metabolite production, making it an eco-friendly approach to sustainable crop management under climate-related stressors.

Climate change is expected to increasingly intensify the water stress that directly impacts crop productivity in the near future. This study integrates the crop water stress index (CWSI) with high-resolution regional climate simulations produced by the weather research and forecasting (WRF) model to evaluate water stress that winter wheat and olive trees will potentially experience in Greece in the future. Decadal, high-resolution climate simulations were generated for both the present and near-future periods using the most recent shared socioeconomic pathways (SSP) framework. A bias-corrected dataset based on 18 models from the Coupled Model Intercomparison Project 6 was used for boundary conditions to mitigate errors associated with individual global model biases. Projections indicated a mean air temperature increase of 1.1–1.7 °C and a relative humidity decrease of up to 3.5%. Mean CWSI increases of up to 6% and 4% were projected in most of the country for winter wheat and olive trees, respectively. The water stress of the winter wheat was also assessed over the three growing stages defined by the FAO. The analysis showed that water stress may occur during all growing stages, inducing potential impacts on tillering, photosynthetic efficiency, biomass accumulation, or yield. Additionally, a water stress threshold (i.e., CWSI > 0.5) was applied for both species in order to carry out a spatial assessment of the water stress that is projected to occur in the future in key winter wheat-, olive oil- and table olive-producing Greek regions. The findings of this study can support the irrigation scheduling and the development of climate-resilient agricultural practices in Greece. The modeling framework that was established in this study can also be applied to other crops and regions in the Mediterranean.