This study investigates the role of 24-epibrassinolide (BR, 10- 2 mu M) in mitigating arsenic (As)-induced stress in maize (Zea mays L. cv. 704). Seedlings were exposed to As at concentrations of 0, 5, 10, 25, 50, 100, and 250 mu M, with or without BR application. Arsenic exposure increased oxidative damage markers such as MDA and H2O2 while BR treatment significantly enhanced antioxidant enzymes activities including ascorbate peroxidase (APX), catalase (CAT), peroxidase (POD), superoxide dismutase (SOD), glutathione reductase (GR) and glutathione Stransferase (GST), reducing reactive oxygen species (ROS) levels, and minimizing oxidative damage. Additionally, BR significantly increased proline, phenolic compounds, flavonoids, and soluble sugars, contributing to osmoprotection and stress tolerance, as well as enhancing FRAP and DPPH antioxidant activities. Furthermore, BR increased amino acids (AAs) such as proline (Pro), cysteine (Cys), glutamine (Gln), and glutamate (Glu). Gene expression analysis revealed significant upregulation of detoxification-related genes including cytochrome P450 monooxygenases (CYPs), GT1, GST27 and multidrug resistance-associated proteins (MRPs) under BR treatment. These findings suggest that BR enhances maize tolerance to As toxicity by activating detoxification pathways, improving antioxidant defense, and stabilizing metabolic processes. The results underscore the potential application of BR in sustainable agriculture to improve crop resilience in As-contaminated soils.

Melatonin (MT) is a crucial hormone that controls and positively regulates plant growth under abiotic stress, but the biochemical and physiological processes of the combination of melatonin seed initiation and exogenous spray treatments and their effects on maize germination and seedling salt tolerance are not well understood. Consequently, in this research, we utilized the maize cultivars Zhengdan 958 (ZD958) and Demeiya 1 (DMY1), which are extensively marketed in northeastern China's high-latitude cold regions, to reveal the modulating effects of melatonin on maize salinity tolerance by determining the impacts of varying concentrations of melatonin on maize seedling growth characteristics, osmoregulation, antioxidant systems, and gene expression. The findings revealed that salt stress (100 mM NaCl) significantly inhibited maize seed germination and seedling development, which resulted in significant increases in the H2O2 and O2- content and decreases in the antioxidant enzyme activity and photosynthetic pigment content in maize seedlings. However, exogenous melatonin considerably reduced the development inhibition caused by salt stress in maize seedlings. Moreover, exogenous melatonin alleviated NaCl-induced membrane damage and oxidative stress, and reduced Na+ content and excessively large quantities of reactive oxygen species (ROS). In addition, exogenous melatonin increased antioxidant enzyme activity and the expression of the antioxidant enzyme genes ZmSOD4, ZmCAT2, and ZmAPX2. This study demonstrates the potential role of combined melatonin seed initiation and foliar spray treatments in mitigating the detrimental effects of salt stress on maize growth, giving a theoretical foundation to future research on the possible advantages of exogenous regulating chemicals in attaining sustainable production in salt-alkaline soils.

The green-belly stink bug is an early pest in the second crop of corn, following soybean. The dynamics of infestations by this pest in systems where corn is defoliated in the early stages is still unknown. Therefore, the objective was to evaluate the feeding of the stink bug on corn subjected to early defoliation. In a greenhouse, used a 2 x 4 factorial design, with two cultivars: BRS3042 VTPRO2 and 1F640PRO2, and four treatments: Without stink bug and with plant cutting (WSB-C); With stink bug before cutting (SB-BC); With stink bug after cutting (SB-AC); With stink bug and without cutting (SB-WC), with ten repetitions. Cutting of the plants was performed at the V3 stage, at a height of five centimeters above the soil. Infestation with stink bugs was carried out five days after emergence and/or after cutting, with two stink bugs per pot. The following were evaluated: injury score, height, stem diameter, fresh and dry plant weight. The plants that were not cut (SB-WC) presented the highest values in height and diameter, resulting in injury scores around 1 compared to those that were infested after the cut (SB-AC), which had scores varying between 3 and 4 and had smaller height and diameter. It was concluded that removing the leaf surface impairs the establishment of the corn plant, and with the infestation of the green-belly stink bug, the severity of the damage increases.

Microplastics (MP) pollution in agricultural soils has become an important environmental problem. Phosphorus (P) is a key nutrient for plant growth. P fertilizers are mainly applied to agricultural fields to achieve the high production expected by farmers. The experiment included two MP levels (0, 1 % w/w) and two P levels (0 mg kg(-1) , 200 mg kg(-1) ) in order to know whether MP effects on wheat and maize are regulated by supplemental P supply. MP decreased plant height, photosynthetic pigment, and chlorophyll fluorescence parameters, while increased ROS and MDA contents. Wheat and maize exhibited distinct strategies in mitigating growth damage caused by MP pollution: wheat primarily increased the AsA contents, while maize predominantly enhanced APX activity. P supply alleviated the MP pollution effect by improving photosynthetic pigments, POD, and PPO activity in wheat and maize. P supply alleviated the MP pollution effect by improving antioxidant enzyme activities in the AsA-GSH cycling in wheat, while increasing non-enzymatic antioxidant contents in the AsA-GSH cycling in maize. The results showed that wheat and maize resisted MP pollution by different mechanisms, and P supply reduced the sensitivity of wheat and maize to MP pollution and its regulatory effect on wheat was better than that on maize. Synopsis: The response of different plants under the same microplastic and phosphorus conditions is limited. We find phosphorus alleviates microplastics pollution on wheat and maize through different regulatory routes.

The prevalence and abundance of plant-parasitic nematodes (PPNs) associated with corn ( Zea mays; Poaceae) in the Anuradhapura district of Sri Lanka are poorly understood. This study investigated the occurrence and population densities of major PPN genera associated with corn. Over 92% of the corn fields were positive for PPNs in all the sampled fields. Major PPN genera identified were Pratylenchus spp. (71.4%), Helicotylenchus spp. (28.6%), Meloidogyne spp. (21.4%), Criconemella spp. (21.4%), and Hoplolaimus spp. (35.7%). The mean population density of Pratylenchus spp. was 2020 nematodes kg-1 of soil, in the Anuradhapura corn fields. During the cropping season from November (2021) to February (2022), all PPN genera except Meloidogyne spp. were observed. Pratylenchus spp. were detected at levels below 1000 nematodes kg-1 of soil at the seedling stage, except in Kelenikawewa where the initial population was 1865 nematodes kg-1 . At the time of harvest, Pratylenchus spp. increased by 2 to 10 folds. These findings suggest a potential impact of Pratylenchus spp. on corn yield in Anuradhapura, highlighting the need for further research to assess damage levels and the overall effect of PPNs on corn production in Sri Lanka.

Maize is among the most significant crops in the world regarding production and yield, but it is highly sensitive to drought, which reduces the growth, photosynthetic efficiency, grain quality, and yield production of a plant. Quantum yield efficiency of photosystem II is a critical photosynthetic component that is susceptible to drought stress. This study intended to investigate the effects of drought stress on growth and morpho-physiological parameters using three maize hybrids ('P-3011w', 'P-3092' and 'iku20') with contrasting soil moisture contents (100%, 40%) at the pre-flowering stage. The stress treatment (40%) was initiated at stage V7, for a period of 15 days; the experimental units were established in a completely randomized design with split-plot arrangement along with three repetitions in 42 L pots using a substrate of peat moss, black soil and poultry manure (1:2:1). The morphological, growth-related and physiological parameters were assessed, including chlorophyll fluorescence (Fv/Fm), which was measured using a LiCor-6400-40 fluorometer. The results showed that all morphological, growth-related and physiological variables decreased under drought stress during the reproductive stage, with the exception of leaf temperature and intercellular CO2 concentration, which increased by 12% and 54%, respectively. Drought stress significantly reduced the photosynthetic chlorophyll fluorescence (43%), due to damage to photosystem II. The lowest percentage of damage to photosystem II (34%) was observed in the iku20 genotype. In contrast, P-3011w and P-3092 had the highest levels of significantly similar damage (49% and 46%, respectively). The correlation analysis showed a highly positive interaction of chlorophyll fluorescence (Fv/Fm) with net photosynthetic rate and stomatal conductance under drought conditions, and multiple regression analysis revealed that the maximum effect on net photosynthetic rate under drought was due to the damage it caused to photosystem II. Thus, iku20 might have a tendency to be able to withstand drought stress in the dry northeast region of Mexico. Overall, we concluded that the photosystem II was negatively impacted by drought stress thus causing a reduction in all physiological, morphological and growth-related variables.

Soil salinization has damaged the soil biological environment and chemical structure, resulting in a decline in soil quality and crop yields, which has caused harm to the ecological environment and human health, and severely hindered the development of the economy. In this experiment, using the 'Ningdan 33' maize seeds as materials, the maize was treated with histidine and salt stress (100 mM NaCl), and photosynthesis, photosynthetic enzyme activity, relative expression of photosynthetic genes of maize were measured. The anatomical structure of the leaves was also observed. The study explored the impact of exogenous histidine treatment on the photosynthesis of maize under salt stress. When the concentration of histidine sprayed on the leaves was 0.5 mM, it had the best effect on promoting photosynthesis in maize under salt stress. 0.5 mM histidine significantly improved the photosynthetic performance ( P N , g s , E , Chl a /Chl b ) of maize under salt stress, significantly improved photosynthesis efficiency (F v /F m , Delta F/F' m , q P were significantly increased. NPQ was significantly decreased), significantly increased the activity of photosynthetic enzymes (PEPC, NADP-ME, PPDK, Rubisco) and the relative expression of photosynthetic genes ( ZmPEPC , ZmNADP-ME , ZmPPDK , ZmRCA ), increased the length of the vascular bundle in the cross- of the leaf, played a certain protective role on the vascular bundle, and improved the efficiency of material transportation under salt stress. Based on the above analysis, 0.5 mM histidine can significantly improve the tolerance of maize under salt stress, which has great application value for planting maize in saline environments.

The ubiquitous metalloid arsenic (As), which is not essential, can be found extensively in the soil and subterranean water of numerous nations, raising substantial apprehensions due to its impact on both agricultural productivity and sustainability. Plants exposed to As often display morphological, physiological, and growthrelated abnormalities, collectively leading to reduced productivity. Polyphenols, operating as secondary messengers within the intricate signaling networks of plants, assume integral functions in the acquisition of resistance to diverse environmental stressors, including but not limited to drought, salinity, and exposure to heavy metals. The pivotal roles played by polyphenols in these adaptive processes underscore their profound significance in plant biology. This study aims to elucidate the impact of hesperidin (HP) and chlorogenic acid (CA), recognized as potent bioactive compounds, on maize plants exposed to As. To achieve this objective, the study examined the physiological and biochemical impacts, including growth parameters, photosynthesis, and chloroplastic antioxidants, of HP (100 mu M) and CA (50 mu M) on Zea mays plants exposed to arsenate stress (AsV, 100 mu M - Na2HAsO4 & sdot;7H2O). As toxicity led to reductions in fresh weight (FW) and dry weight (DW) by 33% and 26%, respectively. However, the application of As+HP and As + CA increased FW by 22% and 40% and DW by 14% and 17%, respectively, alleviating the effects of As stress. As toxicity resulted in the up-regulation of PSII genes (psbA and psbD) and PSI genes (psaA and psaB), indicating a potential response to the re-formation of degraded regions, likely driven by the heightened demand for photosynthesis. Exogenous HP or/and CA treatments effectively counteracted the adverse effects of As toxicity on the photochemical quantum efficiency of PSII (Fv/ Fm). H2O2 content showed a 23% increase under As stress, and this increase was evident in guard cells when examining confocal microscopy images. In the presence of As toxicity, the chloroplastic antioxidant capacity can exhibit varying trends, with either a decrease or increase observed. After the application of CA and/or HP, a significant increase was observed in the activity of GR, APX, GST, and GPX enzymes, resulting in decreased levels of H2O2 and MDA. Additionally, the enhanced functions of MDHAR and DHAR have modulated the redox status of ascorbic acid (AsA) and glutathione (GSH). The HP or CA-mediated elevated levels of AsA and GSH content further contributed to the preservation of redox homeostasis in chloroplasts facing stress induced by As. In summary, the inclusion of HP and CA in the growth medium sustained plant performance in the presence of As toxicity by regulating physiological and biochemical characteristics, chloroplastic antioxidant enzymes, the AsAGSH cycle and photosynthesis processes, thereby demonstrating their significant potential to confer resistance to maize through the mitigation of As-induced oxidative damage and the safeguarding of photosynthetic mechanisms.

The morphology of a plant's root is strongly affected by the compaction of the growth medium, the size of its particles, or the presence of non -movable obstacles. However, little is known about the effect of these characteristics on root anatomy and mechanical properties of the root tissues. Anatomical features of maize roots grown in media that varied in density and/or structure (soil, glass beads, vermiculite) were analyzed on cross -sections through the elongation and maturation zones of the roots of 14 -day -old seedlings. The sections were stained for lignin and suberin to recognize the developmental stages of exodermis and endodermis. Cortex thickness, number of cortical cell layers, and diameter of the vascular cylinder (stele) were measured in both zones. The Young's modulus of the roots was determined using mechanical tensile tests. Assuming that the root can be considered a composite material, a model was used that allowed, for the first time, the estimation of the mechanical properties of the stele and cortex. While the cell arrangement of roots grown in a medium with high density and fine movable particles (soil) was regular, roots grown in a medium with low density and light particles (vermiculite) and a medium with high density and large unmovable particles (glass beads) showed early damage of the rhizodermis and impaired cell arrangement in the cortex and vascular cylinder. In these roots, the exodermis and endodermis matured closer to the root tip than in roots from the soil. The vermiculite roots were the most outliers in terms of morphometric parameters and mechanical properties. The Young's modulus of the stele was many times greater than the Young's modulus of the cortex in the roots of all variants. Of the media used in the experiment, the soil appears to be most favorable for the maize root growth and development.