Maize (Zea mays L.) is a chilling-sensitive plant. Chilling stress in the early seedling stage seriously limits the growth, development, productivity and geographic distribution of maize. Salicylic acid (SA) is a plant growth regulator involved in the defenses against abiotic and biotic stresses as well as in plant development. However, the physiological mechanisms underlying the effects of foliar applied SA on different maize inbred lines under chilling stress are unclear. Two inbred lines, cold-sensitive cv. C546 and cold-tolerant cv. B125, were used to study the effects of SA on the growth and physiology of maize seedlings. The results showed that the application of SA at 50 mg/L on the leaves of maize seedlings under 4 °C decreased the relative electrolyte conductivity (REC) and the malondialdehyde (MDA) and reactive oxygen species (ROS) (H₂O₂ and O_2⁻) content due to increased superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX) activity; SA also improved photosynthesis in the seedlings through increased chlorophyll content, enhanced Pn and Gs, and decreased Ci. SA application also increased the proline content and the relative water content (RWC) in the maize seedlings, thereby improving their osmotic adjustment capacity. The increase rate caused by SA of plant height and dry weight in C546 were 10.5% and 5.4% higher than that in B125 under 4 °C. In conclusion, SA promotes maize seedling growth and physiological characteristics, thus enhancing chilling resistance and the effect of SA on the chilling resistance of cold-sensitive cv. was stronger than that on cold-tolerant cv. at the low temperature.

Maize (Zea mays L.) is one of the most important crops worldwide. However, low temperature limits seed germination and seedling growth of maize, which can in turn affect grain yield. The calcium ion (Ca2+) is the second messenger involved in the response to environmental-stimuli-induced signal transduction networks. The underlying physiological mechanisms related to the effects of exogenous Ca2+ treatment of different maize cultivars under low temperature are unclear. We selected two inbred lines, cold-sensitive cv. C546 and cold-tolerant cv. Y478, for studying the effects of Ca2+ on seed germination, photosynthesis, antioxidant enzymes and the osmotic regulation of seedling resistance to low temperature. The optimal concentration of CaCl2 was 80 mmol L–1, which significantly improved the germination percentage at temperatures <10°C. Application of CaCl2 at this concentration under cold stress mitigated the degree of membrane injury and improved the antioxidant enzyme system through reduced relative electrolyte conductivity and malondialdehyde content, increased the soluble protein content, and enhanced superoxide dismutase and peroxidase activity. CaCl2 also significantly increased chlorophyll fluorescence indicators (Fv/Fo, Fv/Fm) and the photosynthetic rate. We conclude that exogenous CaCl2 at a concentration of 80 mmol L–1 protects the function and structure of the membrane and photosystems, improves antioxidant enzyme activity and increases osmotic regulatory substances under cold stress. These results improve our understanding of the mechanisms of Ca2+ and contribute to the development of cold-tolerant maize varieties.

In Northeast China, waterlogging has emerged as a significant challenge due to climate change, particularly during the June–August period when spring maize (Zea mays L.), at the post-tasseling phase, impedes a comprehensive understanding of responses and the development of resistance technologies. 2-(3,4-dichlorophenoxy) triethylamine (DCPTA) is suitable for the entire lifecycle of various economic and food crops, improving crop quality and enhancing stress resistance. The study investigated the ear leaf photosynthesis in relation to the root antioxidant systems’ differential responses of spring maize to waterlogging among the tasseling (VT), vesicle (R2) and dough (R4) stages, and the exogenous DCPTA regulating effect. Results revealed that waterlogging inhibited root physiological activity due to oxidative damage. Consequently, the stomatal restriction and non-stomatal restriction on photosynthesis appeared successively, and R4 was the most sensitive stage. Pretreatment with DCPTA reduced stomatal restriction by maintaining water transfer to the leaf through maintaining root physiological activity via enhanced ascorbate–glutathione cycle. Delayed non-stomatal restriction appeared due to relatively stable chlorophyll content and photosynthetic activities, and VT stage exhibited the highest susceptibility to DCPTA. The study provides a necessary theoretical foundation for comprehending the physiological mechanisms underlying yield formation of spring maize under waterlogging stress in Northeast China, and offers valuable insights for the development of chemical regulation technology.

Timely detection of pathogen spores is fundamental to ensuring early intervention and reducing the spread of corn diseases, like northern corn leaf blight, corn head smut, and corn rust. Traditional spore detection methods struggle to identify spore-level targets within complex backgrounds. To improve the recognition accuracy of various maize disease spores, this study introduced the YOLOv8s-SPM model by incorporating the space-to-depth and convolution (SPD-Conv) layers, the Partial Self-Attention (PSA) mechanism, and Minimum Point Distance Intersection over Union (MPDIoU) loss function. First, we combined SPD-Conv layers into the Backbone of the YOLOv8s to enhance recognition performance on small targets and low-resolution images. To improve computational efficiency, the PSA mechanism was incorporated within the Neck layer of the network. Finally, MPDIoU loss function was applied to refine the localization performance of bounding boxes. The results revealed that the YOLOv8s-SPM model achieved 98.9% accuracy on the mixed spore dataset. Relative to the baseline YOLOv8s, the YOLOv8s-SPM model yielded a 1.4% gain in accuracy. The improved model significantly improved spore detection accuracy and demonstrated superior performance in recognizing diverse spore types under complex background conditions. It met the demands for high-precision spore detection and filled a gap in intelligent spore recognition for maize, offering an effective starting point and practical path for future research in this field.

The RIQ gene can optimize the structure of light-harvesting complex II by regulating the degree of granum stacking, and ultimately participates in plant light stress responses. The GmRIQ2 gene contributes to plant photoprotection and may be involved in negative regulation of yield. To understand the regulatory mechanisms of GmRIQ2 expression, we isolated the GmRIQ2 promoter (PGmRIQ2) from the KenFeng 16 soybean genome. Sequence analysis showed that several cis-acting elements were involved in hormone responsiveness, seed-specific regulation, anaerobic induction and light responsiveness. PGmRIQ2 was expressed in soybean roots. GUS activity was detected in Arabidopsis thaliana rosette leaves, stems and roots, indicating that PGmRIQ2 tended to drive expression in rosette leaf vascular tissue and had spatiotemporal expression characteristics at the early growth stage. Three promoter deletion fragments of 450 bp, 284 bp and 194 bp were obtained by 5′ deletion. These three fragments all drove GUS gene expression in Arabidopsis thaliana rosette leaves, stems and roots. GUS gene expression decreased with deletion fragment truncation. In addition, the PGmRIQ2 auxin (IAA), abscisic acid (ABA) and methyl jasmonate (MeJA) response elements were located at base pairs −1661~−450, −450~−284 and −284~−194, respectively, and the promoter was induced by IAA, ABA, MeJA and light.

Lodging imposes substantial constraints on maize yield potential and agronomic efficiency, critically undermining productivity and resource optimization in cultivation systems. This study aimed to elucidate the mechanism whereby ethephon enhances lodging resistance and analyze the sensitivity differences to ethephon among distinct maize inbred lines. Through exogenous application of ethephon (200 and 400 mg/L, S1 and S2 treatments) to four classic maize inbred lines (Zheng58, Chang7-2, PH6WC, and PH4CV), we systematically evaluated its effects on plant morphology, stalk biomechanical properties, and lignin biosynthesis. Results demonstrated that ethephon optimized plant morphology through reductions in plant height, ear height, leaf area, leaf angle, and internode length. Significant augmentations in stalk bending resistance (a maximum increase of 52.61% in PH4CV) and puncture strength (most pronounced in Zheng58) were mechanistically associated with increased lignin content and enhanced activity of key biosynthetic enzymes [cinnamyl alcohol dehydrogenase (CAD), phenylalanine ammonia-lyase (PAL), and 4-coumarate-CoA ligase (4CL)], with PH6WC exhibiting the most robust enzymatic response. These findings underscored genotype-specific regulatory effects of ethephon, bridging the knowledge gap regarding its molecular–physiological interplay with maize genotypes. The study provides critical insights for precision breeding and optimization strategies employing plant growth regulators to improve maize lodging resistance.