To explore strategies for the safe utilization of farmland co-contaminated with cadmium (Cd) and lead (Pb), this field study systematically evaluated the impacts of humic acid (HA) and potassium fulvate (PF) at different application rates (0, 1500, 3000, and 4500 kg·ha⁻¹) on the growth, yield, and translocation of Cd and Pb within the soil–plant system of maize (Zea mays L.). The results showed that while HA and PF did not significantly alter total soil Cd and Pb concentrations, they markedly reduced their bioavailable fractions. This mitigation of heavy metal phytotoxicity significantly promoted maize growth and yield, with the high-dose HA treatment increasing yield by a maximum of 32.9%. Both amendments dose-dependently decreased Cd and Pb concentrations, bioconcentration factors (BCF), and translocation factors (TF) in all maize tissues, particularly in the grains. At equivalent application rates, PF was slightly more effective than HA in reducing heavy metal concentrations in the grains. Notably, a significant positive correlation was observed between Cd and Pb concentrations across all plant parts, confirming a synergistic accumulation and translocation mechanism. This synergy provides a physiological explanation for the broad-spectrum immobilization efficacy of these humic substances. In conclusion, applying HA and PF presents a dual-benefit strategy for increasing yield and reducing risks in Cd- and Pb-contaminated farmlands. This study proposes a differentiated application approach: PF is the preferred option when ensuring food-grade safety is the primary goal, whereas high-dose HA is more advantageous for maximizing yield in soils with low-to-moderate contamination risk.

The southwestern region of China is one of the major maize (Zea mays L.)-producing areas and a concentrated zone of farmland contaminated by heavy metals (HMs). Selection of maize varieties with low accumulation of HMs under complex HM pollution conditions is one the most feasible and effective ways for safe utilization of HM-polluted farmland. In this study, we conducted field experiments to investigate the differences in biological traits among 28 local maize varieties under combined soil pollution with Cd, Pb, As, Cr, and Hg. We analyzed the absorption, accumulation, and transport characteristics of Cd, Pb, As, and Cr in various parts of the maize plant (Hg was not detected in any part of maize plants) and explored the relationships of HM contents in different parts of maize with soil HM contents through cluster analysis, correlation analysis, and principal component analysis. The results indicated that among different biological traits of maize, root length, root dry weight, and plant height were the most significantly influenced by soil HM content, while stem dry weight was the least affected. The accumulation capacity of various maize parts for HMs followed the order of grains < stems < cobs < leaves < roots, while the transport capacity followed the order of root–grain < root–stem < cob–grain < stem–cob < stem–leaf. In addition, the accumulation capacity of maize grains for HMs followed the order of As < Cr < Pb < Cd. Different HMs exhibited synergistic effects in various maize parts, except for the stem, particularly in the grains. A synchronous transport mechanism was observed for As and other HMs in different parts. The accumulation of HMs in maize was primarily derived from human activities such as the extraction, storage, and smelting of non-ferrous metals, while the HMs in soil parent material and weathering products played a secondary role. The yield of the tested maize varieties ranged from 7377.6 to 11,037.0 kg·hm⁻², with M5 (Haoyu 1511) achieving the highest yield. M2, M4, M5, M9, M10, M21, and M25–28 were identified as suitable varieties with low Cd, Pb, As, and Cr accumulation for popularization in HM-contaminated soils in southwestern China due to their low accumulation of HMs.

Potentially toxic element (PTE) co-contamination in farmland severely threatens global food safety. To identify effective remediation strategies, large-scale field trials were conducted in two karst regions of Southwest China highly co-contaminated with Cd, Pb, As, Cr, and Hg. The efficacy of seven commercial soil amendments (biochar (BC), fused calcium–magnesium phosphate (FCMP), humic acid (HA), potassium humate (KH), oyster shell powder (OS), composite passivator (PA), and quicklime (QL)) on soil physicochemical properties, PTE bioavailability, maize (Zea mays L.) yield, and plant tissue distribution was systematically evaluated. The results indicated that organic amendments, specifically BC, HA, and KH, consistently outperformed inorganic treatments. These organic materials significantly decreased the diethylenetriaminepentaacetic acid (DTPA)-extractable fractions of cationic PTEs (e.g., Cd and Pb decreased by up to 39.5% under KH treatment) without inadvertently mobilizing As, unlike the alkaline inorganic amendments. This reduction in soil bioavailability closely correlated with improved plant performance, leading to maximum increases in root biomass (up to 130% with BC) and grain yield (up to 27.6% with HA). Furthermore, BC and humic substances effectively restricted PTE accumulation in grains (Cd and Pb reduced by up to 42.1%). Tissue distribution analysis revealed a consistently low root-to-stem translocation factor (TF < 0.2), indicating that roots acted as the primary sink for absorbed PTEs. This study indicates that commercial organic amendments support the use of a superior, broad-spectrum strategy for mitigating multi-PTE risks and ensuring safe agricultural utilization in severely co-contaminated areas.

Grapevine downy mildew, caused by the oomycete pathogen Plasmopara viticola (P. viticola), is one of the most devastating diseases threatening the global grape industry. The pathogen invades host plants through stomata, triggering a series of highly coordinated physiological disorders and biochemical defense events. This review systematically summarizes the dynamic changes in morphological structures (stomatal characteristics), physiological functions (photosynthesis, membrane system integrity, and carbon metabolism), and multi-level biochemical defense systems (reactive oxygen species (ROS) scavenging enzyme system, phenylpropanoid metabolic pathway, pathogenesis-related proteins, and phenolic compounds) in grapevines following infection. It focuses on analyzing the differences in the timing, intensity, and metabolic reprogramming of defense responses between resistant and susceptible cultivars, pointing out that the essence of disease resistance lies in early pathogen recognition and rapid defense induction. The conflicting conclusions regarding indicators such as soluble sugars, peroxidase (POD), and superoxide dismutase (SOD) are discussed from the perspectives of experimental systems, cultivar genetic backgrounds, and pathogen physiological race differences. Furthermore, the known physiological and biochemical alterations are linked to upstream signaling pathways, including salicylic acid and jasmonic acid (SA/JA), calcium signaling, and mitogen-activated protein kinase (MAPK) cascades. Recent advances in revealing resistance mechanisms in the omics era are also introduced. Finally, future research directions are proposed, including constructing multi-indicator dynamic evaluation models, verifying key gene functions using gene editing, exploring the potential of epigenetic regulation, and developing integrated control strategies combined with microbiome research. This review aims to provide theoretical support for grapevine downy mildew resistance breeding and sustainable disease management.