Maize System Research Articles

Effect of Biogas Slurry on the Soil Properties and Microbial Composition in an Annual Ryegrass-Silage Maize Rotation System over a Five-Year Period.

Soil health is seriously threatened by the overuse of chemical fertilizers in agricultural management. Biogas slurry is often seen as an organic fertilizer resource that is rich in nutrients, and its use has the goal of lowering the amount of chemical fertilizers used while preserving crop yields and soil health. However, the application of continuous biogas slurry has not yet been studied for its long-term impact on soil nutrients and microbial communities in a rotation system of annual ryegrass-silage maize (Zea mays). This study aimed to investigate the impacts on the chemical properties and microbial community of farmland soils to which chemical fertilizer (NPK) (225 kg ha-1), biogas slurry (150 t ha-1), and a combination (49.5 t ha-1 biogas slurry + 150 kg ha-1 chemical fertilizer) were applied for five years. The results indicated that compared to the control group, the long-term application of biogas slurry significantly increased the SOC, TN, AP, and AK values by 45.93%, 39.52%, 174.73%, and 161.54%, respectively; it neutralized acidic soil and increased the soil pH. TN, SOC, pH, and AP are all important environmental factors that influence the structural composition of the soil's bacterial and fungal communities. Chemical fertilizer application significantly increased the diversity of the bacterial community. Variation was observed in the composition of soil bacterial and fungal communities among the different treatments. The structure and diversity of soil microbes are affected by different methods of fertilization; the application of biogas slurry not only increases the contents of soil nutrients but also regulates the soil's bacterial and fungal community structures. Therefore, biogas slurry can serve as a sustainable management measure and offers an alternative to the application of chemical fertilizers for sustainable intensification.

The Formal Seed System of Maize in Ethiopia: Implications for Reducing the Yield Gap

Smallholder farmers’ access to and use of quality seeds of improved varieties and hybrids is an integral component of sustainable maize production and the reduction of the yield gap in Ethiopia. Formal seed supply systems play a pivotal role in ensuring farmers’ access to good quality seed and increasing the productivity of maize. However, the contribution of the formal seed system to the increase in the average national maize yield in the country is not well documented. This paper specifically analyzes the formal seed supply systems and contributions of improved seed to maize productivity increase in Ethiopia. Secondary sources of information, including published and unpublished data, were used. Analysis of the seed value chain from research to commercial seed producers indicated that public and private maize hybrids dominate the formal seed system. Increased use of improved seed and associated management practices has contributed to the yield increase at the national level. For every 10,000 MT of additional maize-improved seed used by smallholder farmers, the national average maize yield increased by 400 kg per hectare (R sq. = 0.59). Hence, in addition to other yield-increasing technologies and extension support, ensuring the availability of improved seed to farmers can significantly contribute to reducing the maize yield gap between the national average yield and the average yield from on-farm demonstrations already attained by farmers in Ethiopia. Various policy interventions are suggested to improve the maize seed system performance and increase the supply of maize improved seeds.

Reducing energy and carbon footprint in semi-arid irrigated cropping systems through crop diversification

Energy and carbon (C) footprints of agricultural production practices have garnered high attention due to rising energy costs and increasing global warming. However, the contribution of conservation and regenerative farming practices, including cover cropping, on energy and C footprints have not yet been documented for cropping systems in arid and semi-arid regions. This study evaluated the energy and C footprint of cover crop integrated silage maize (Zea mays L.) and sorghum (Sorghum bicolor L. Moench) production systems in the semi-arid region of the southwestern US. The treatments were mixtures of winter cover crops: i) grasses and legumes (GL), ii) grasses, brassicas, and legumes (GBL), iii) grasses and brassicas (GB), and iv) no cover crops (NCC) control for each crop production system. Results showed cover crops had 24.1–24.5% greater energy input than NCC. In silage maize rotation, energy output was 17–22% greater in GBL and GL than in NCC. In silage sorghum rotation, the energy output was 15–24% greater in all cover crops than in NCC. The resulting net energy was 16–21% greater in GBL and GL than in NCC under silage maize, while it was 18–24% greater in GBL and GB than in NCC under silage sorghum. In the silage maize system, the C-footprint per kg yield was not different among treatments, whereas in silage sorghum, it was 58% greater in GBL than in NCC. The benefit-to-cost ratio was greater than one for all treatments, but the additional revenue through C credit programs could make cover cropping a more feasible and beneficial approach, improving economic and environmental sustainability while producing silage crops. While the C footprint was crop rotation specific, cover cropping should be encouraged over crop-fallow systems to producers in semi-arid environments to reduce energy usage and increase C-credit benefits. Clear national and state policy on the C credit program will also enhance economic and environmental benefits by adopting cover cropping and other regenerative farming practices.

Linkage mapping and genomic prediction of grain quality traits in tropical maize (Zea mays L.).

The suboptimal productivity of maize systems in sub-Saharan Africa (SSA) is a pressing issue, with far-reaching implications for food security, nutrition, and livelihood sustainability within the affected smallholder farming communities. Dissecting the genetic basis of grain protein, starch and oil content can increase our understanding of the governing genetic systems, improve the efficacy of future breeding schemes and optimize the end-use quality of tropical maize. Here, four bi-parental maize populations were evaluated in field trials in Kenya and genotyped with mid-density single nucleotide polymorphism (SNP) markers. Genotypic (G), environmental (E) and G×E variations were found to be significant for all grain quality traits. Broad sense heritabilities exhibited substantial variation (0.18-0.68). Linkage mapping identified multiple quantitative trait loci (QTLs) for the studied grain quality traits: 13, 7, 33, 8 and 2 QTLs for oil content, protein content, starch content, grain texture and kernel weight, respectively. The co-localization of QTLs identified in our research suggests the presence of shared genetic factors or pleiotropic effects, implying that specific genomic regions influence the expression of multiple grain quality traits simultaneously. Genomic prediction accuracies were moderate to high for the studied traits. Our findings highlight the polygenic nature of grain quality traits and demonstrate the potential of genomic selection to enhance genetic gains in maize breeding. Furthermore, the identified genomic regions and single nucleotide polymorphism markers can serve as the groundwork for investigating candidate genes that regulate grain quality traits in tropical maize. This, in turn, can facilitate the implementation of marker-assisted selection (MAS) in breeding programs focused on improving grain nutrient levels.

Technology for Production of Wheat Doubled Haploid via Maize Pollen Induction—Updated Review

Chromosome elimination resulting in haploids is achieved by rapid loss of chromosomes from one parent during the zygote stage and is an important procedure to produce doubled haploid (DH) lines in plants. During crosses between an emasculated wheat (Triticum aestivum L.) and maize (Zea mays L.) as pollen donors, the complete loss of maize chromosomes results in wheat haploid embryos. Through embryo rescue and chromosome doubling processes, pure lines with stable traits can be quickly obtained. The technique is called the “Wheat × Maize System”. Although this technology is not new, it remains a practical approach to date. In order to optimize and improve this technology and to achieve its maximum potential in the winter wheat area of China, this paper reviews the previous and ongoing research and technical procedures for the production of wheat DH lines via the maize pollen induction and presents outlooks on DH research and its application in wheat breeding.

Reducing greenhouse gas intensity using a mixture of controlled-release urea and common urea combining suitable maize varieties in a summer maize system

The one-time application of common urea blended with controlled-release urea (CRU) is considered effective for improving nitrogen use efficiency and grain yield and reducing the greenhouse gas emissions of summer maize in intensive agricultural systems. However, the trade-off between the economic and environmental performances of different blended fertilizer treatments for different maize varieties remains unclear. Therefore, a consecutive two-year field experiment was conducted in the North China Plain to study the effects of different ratios of CRU and common urea on the yield, nitrous oxide (N2O) emissions, yield-scaled total N2O emissions, greenhouse gas intensity (GHGI), and net ecosystem economic benefit (NEEB) in 2021 and 2022. Four N fertilizer treatments with equal rate at 180 kg N ha−1 were applied as N180U (all Urea), N180C1(1/3CRU), N180C2(2/3CRU), and N180C (all CRU), and two maize varieties (JNK728-yellow ripe variety and ZD958-green ripe variety) were used. The N180C1 and N180C2 treatments produced the highest grain yield in varieties JNK728 and ZD958 (9.4–11.5 t ha−1 and 9.0–11.0 t ha−1), respectively. Compared to the N180U treatment (conventional method), the N180C1 treatment reduced the GHGI (24.8 %–25.9 %) and increased the NEEB (33.1 %–33.4 %) in the JNK728 variety, whereas the N180C2 treatment reduced the GHGI (16.9 %–28.8 %) and increased the NEEB (27.2 %–48.1 %) in the ZD958 variety. The study concludes that a one-time application of blended nitrogen fertilizer in suitable varieties can minimize the GHGI and maximize the NEEB, which is an effective strategy for balancing yield and nitrogen efficiency in the summer maize system in the North China Plain.

Paenibacillus lentimorbus alleviates nutrient deficiency-induced stress in Zea mays by modulating root system architecture, auxin signaling, and metabolic pathways.

Paenibacillus lentimorbus reprograms auxin signaling and metabolic pathways for modulating root system architecture to mitigate nutrient deficiency in maize crops. The arable land across the world is having deficiency and disproportionate nutrients, limiting crop productivity. In this study, the potential of plant growth-promoting rhizobacteria (PGPR) viz., Pseudomonas putida, Paenibacillus lentimorbus, and their consortium was explored for growth promotion in maize (Zea mays) under nutrient-deficient conditions. PGPR inoculation improved the overall health of plants under nutrient-deficient conditions. The PGPR inoculation significantly improved the root system architecture and also induced changes in root cortical aerenchyma. Based on plant growth and physiological parameters inoculation with P. lentimorbus performed better as compared to P. putida, consortium, and uninoculated control. Furthermore, expression of auxin signaling (rum1, rul1, lrp1, rtcs, rtcl) and root hair development (rth)-related genes modulated the root development process to improve nutrient acquisition and tolerance to nutrient-deficient conditions in P. lentimorbus inoculated maize plants. Further, GC-MS analysis indicated the involvement of metabolites including carbohydrates and organic acids due to the interaction between maize roots and P. lentimorbus under nutrient-deficient conditions. These findings affirm that P. lentimorbus enhance overall plant growth by modulating the root system of maize to provide better tolerance to nutrient-deficient condition.

DNA- and Selectable-Marker-Free Genome-Editing System Using Zygotes from Recalcitrant Maize Inbred B73.

Genome-editing tools such as the clustered regularly interspaced short palindromic repeats/Cas9 (CRISPR/Cas9) system have become essential tools for increasing the efficiency and accuracy of plant breeding. Using such genome-editing tools on maize, one of the most important cereal crops of the world, will greatly benefit the agriculture and the mankind. Conventional genome-editing methods typically used for maize involve insertion of a Cas9-guide RNA expression cassette and a selectable marker in the genome DNA; however, using such methods, it is essential to eliminate the inserted DNA cassettes to avoid legislative concerns on gene-modified organisms. Another major hurdle for establishing an efficient and broadly applicable DNA-free genome-editing system for maize is presented by recalcitrant genotypes/cultivars, since cell/tissue culture and its subsequent regeneration into plantlets are crucial for producing transgenic and/or genome-edited maize. In this study, to establish a DNA-free genome-editing system for recalcitrant maize genotypes/cultivars, Cas9-gRNA ribonucleoproteins were directly delivered into zygotes isolated from the pollinated flowers of the maize-B73 cultivar. The zygotes successfully developed and were regenerated into genome-edited plantlets by co-culture with phytosulfokine, a peptide phytohormone. The method developed herein made it possible to obtain DNA- and selectable-marker-free genome-edited recalcitrant maize genotypes/cultivars with high efficiency. This method can advance the molecular breeding of maize and other important cereals, regardless of their recalcitrant characteristics.

Benefitting productivity and the environment: Current and future maize cropping systems improve yield while reducing nitrate load.

Increases in cereal crop yield per area have increased global food security. "Era" studies compare historical and modern crop varieties in controlled experimental settings and are routinely used to understand how advances in crop genetics and management affect crop yield. However, to date, no era study has explored how advances in maize (Zea mays L.) genetics and management (i.e., cropping systems) have affected environmental outcomes. Here, we developed a cropping systems era study in Iowa, USA, to examine how yield and nitrate losses have changed from "Old" systems common in the 1990s to "Current" systems common in the 2010s, and to "Future" systems projected to be common in the 2030s. We tested the following hypothesis: If maize yield and nitrogen use efficiency have improved over previous decades, Current and Future maize systems will have benefits to water quality compared to Old systems. We show that not only have maize yield and nitrogen use efficiency (kg grain kg-1 N), on average, improved over time but also yield-scaled nitrate load + soil nitrate was reduced by 74% and 91% from Old to Current and Future systems, respectively. Continuing these trajectories of improvement will be critical to meet the needs of a growing and more affluent population while reducing deleterious effects of agricultural systems on ecosystem services.

Changes in microbial community structure and yield responses with the use of nano-fertilizers of nitrogen and zinc in wheat–maize system

The growing popularity of nano-fertilization around the world for enhancing yield and nutrient use efficiency has been realized, however its influence on soil microbial structure is not fully understood. The purpose of carrying out this study was to assess the combined effect of nano and conventional fertilizers on the soil biological indicators and crop yield in a wheat–maize system. The results indicate that the at par grain yield of wheat and maize was obtained with application of 75% of recommended nitrogen (N) with full dose of phosphorus (P) and potassium (K) through conventional fertilizers along with nano-N (nano-urea) or nano-N plus nano-Zn sprays and N100PK i.e. business as usual (recommended dose of fertilizer). Important soil microbial property like microbial biomass carbon was found statistically similar with nano fertilizer-based management (N75PK + nano-N, and N75PK + nano-N + nano-Zn) and conventional management (N100PK), during both wheat and maize seasons. The experimental data indicated that the application of foliar spray of nano-fertilizers along with 75% N as basal is a sustainable nutrient management approach with respect to growth, yield and rhizosphere biological activity. Furthermore, two foliar sprays of nano-N or nano-N + nano-Zn curtailed N requirement by 25%, furthermore enhanced soil microbial diversity and the microbial community structure. The specific microbial groups, including Actinobacteria, Bacteroidia, and Proteobacteria, were present in abundance and were positively correlated with wheat and maize yield and soil microbial biomass carbon. Thus, one of the best nutrient management approaches for sustaining productivity and maintaining sound microbial diversity in wheat–maize rotation is the combined use of nano-fertilizers and conventional fertilizers.

Can high-yielding maize system decrease greenhouse gas emissions largely while simultaneously enhancing economic and ecosystem benefits through the “Rhizobiont” concept? Evidence from field

Ensuring high grain yields while minimizing environmental costs is a pressing imperative aligned with the Sustainable Development Goals (SDGs). In this study, we sought to establish a high-yielding maize system (HYMS) by implementing the innovative “Rhizobiont” concept for nutrient management, while substantially reducing greenhouse gas emissions. A 2-yr field study was conducted in a station of China Agriculture University (Wuqiao) with six treatments. The HYMS was established to achieve a harmonious equilibrium among genetic factors, environmental conditions, and management practices. HYMS demonstrated a significant boost in grain yield, averaging 12,706.6 kg ha−1 in 2021 and 13,676.4 kg ha−1 in 2022. These represented substantial increases of 25.6 % and 25.5 %, respectively, when compared to the current farmers practices (CP). More importantly, the N rate in HYMS was optimized to 148.2 kg ha−1 in 2021 and 138.0 kg ha−1 in 2022 with the implementation of the “Rhizobiont” concept. This represented a remarkable reduction of 35.5 % to 39.9 % in N application compared to CP. As a direct consequence, the measured cumulative emissions of greenhouse gases such as CO2, N2O, and CH4 in HYMS were notably decreased, showing reductions of 24.1 %, 36.0 %, and 7.0 %, respectively, compared to CP. Furthermore, the carbon intensity in HYMS was significantly reduced by 43.7 %. These considerable reductions in fertilizer use translated into tangible economic benefits (EB) and ecosystem economic benefit (EEB) in HYMS. EB was found to be 90.9 % higher, while EEB was 117.9 % higher than CP. These findings underscore the vast potential of HYMS and the “Rhizobiont” concept in promoting sustainable agriculture, with far-reaching implications for global food security and the well-being of smallholder farmers.

Mixed cropping system of maize and bean as a local source of N-substances for the nutrition of farm animals

In this study, we investigated the quality of mixed cropping system (MCS) composed of maize and bean in comparison with maize grown as monoculture. Experimental stands were established using the precision vacuum seeding machine during a single crossing of the plot. Inter-row distance was 0.375 m, and regularly alternating experimental crops were maize (Zea mays L.) and common bean (Phaseolus vulgaris L.). Experimental variants included maize alone (M) in an amount of 80,000 seeds per hectare and maize (M-MCS) with bean (B-MCS) in a 1:1 ratio (80,000: 80,000 individuals) in MCS. Average yield of N-substances (t/ha) in the biomass obtained from individual variants was 2.36 t/ha in the pure maize culture and 3.09 t/ha in the mixed culture (by 30.9% more). The difference was statistically significant. On the other hand, differences in the content of N-substances (protein) were not found. Results of the experiment for the whole period from 2020–2022 also indicated that the presence of bean in the mixed crop statistically significantly increased contents of acid detergent fibre and crude fibre. On the other hand, compared with the biomass of maize monoculture, bean reduced contents of starch and lipids in the maize biomass. The measured results indicate that biomass from mixed cropping systems has a higher potential to fix more N than biomass from the maize monoculture which is important for digestibility of fodder in livestock production.

G × E interaction studies under natural farming and inorganic production system in maize (Zea mays L.)

G × E interaction studies under natural farming and inorganic production system in maize (Zea mays L.)

Optimized nitrogen application for maximizing yield and minimizing nitrogen loss in film mulching spring maize production on the Loess Plateau, China

Excessive use of N fertilizers (driven by high-yield goals) and its consequent environmental problems are becoming increasingly acute in agricultural systems. A 2-year field experiment was conducted to investigate the effects of three N application methods (application of solid granular urea once (OF) or twice (TF), application of solid granular urea mixed with controlled-release urea once (MF)), and six N rates (0, 60, 120, 180, 240, and 300 kg N ha−1) on maize yield, economic benefits, N use efficiency, and soil N balance in the maize (Zea mays L.) film mulching system on the Loess Plateau, China. The grain yield and economic return of maize were significantly affected by the N rate and application method. Compared with the OF treatment, the MF treatment not only increased the maize yield (increased by 9.0–16.7%) but also improved the economic return (increased by 10.9–25.8%). The agronomic N use efficiency (NAE), N partial factor productivity (NPFP) and recovery N efficiency (NRE) were significantly improved by 19.3–66.7, 9.0–16.7 and 40.2–71.5%, respectively, compared with the OF treatment. The economic optimal N rate (EONR) of the OF, TF, and MF was 145.6, 147.2, and 144.9 kg ha−1 in 2019, and 206.4, 186.4, and 146.0 kg ha−1 in 2020, respectively. The apparent soil N loss at EONR of the OF, TF, and MF were 97.1–100.5, 78.5–79.3, and 50.5–68.1 kg ha−1, respectively. These results support MF as a one-time N application method for delivering high yields and economic benefits, with low N input requirements within film mulching spring maize system on the Loess Plateau.

Gene editing of ZmGA20ox3 improves plant architecture and drought tolerance in maize.

Editing ZmGA20ox3 can achieve the effect similar to applying Cycocel, which can reduce maize plant height and enhance stress resistance. Drought stress, a major plant abiotic stress, is capable of suppressing crop yield performance severely. However, the trade-off between crop drought tolerance and yield performance turns out to be significantly challenging in drought-resistant crop breeding. Several phytohormones [e.g., gibberellin (GA)] have been reported to play a certain role in plant drought response, which also take on critical significance in plant growth and development. In this study, the loss-of-functionmutations of GA biosynthesis enzyme ZmGA20ox3 were produced using the CRISPR-Cas9 system in maize. As indicated by the result of 2-year field trials, the above-mentioned mutants displayed semi-dwarfingphenotype with the decrease of GA1, and almost no yield loss was generated compared with wild-type(WT)plants. Interestingly, as revealed by the transcriptome analysis, differential expressed genes (DEGs) were notably enriched in abiotic stress progresses, and biochemicaltests indicated the significantly increased ABA, JA, and DIMBOA levels in mutants, suggesting that ZmGA20ox3 may take on vital significance in stress response in maize. The in-depth analysis suggested that the loss function of ZmGA20ox3 can enhance drought tolerance in maize seedling, reduce Anthesis-Silking Interval (ASI)delay while decreasing the yield loss significantly in the field under drought conditions. The results of this study supported that regulating ZmGA20ox3 can improve plant height while enhancing drought resistance in maize, thus serving as a novel method for drought-resistant genetic improvement in maize.

Management practices influence biocontrol potential of generalist predators in maize cropping systems

AbstractIntensification of conventional agriculture is a leading cause of negative environmental impact, loss of biodiversity, and reduced delivery of ecosystem services in agroecosystems. Maize, due to its growth habits and cultivation management, provides a poor habitat for beneficial arthropods. Several strategies are available to make maize cropping systems more sustainable and to promote biodiversity at field level. The present study evaluates the effects of various maize cropping systems – precisely, maize continuous monoculture, maize multiple cropping, and three mixed cropping systems (maize‐runner bean, maize‐sorghum, and maize‐flower strips) – on generalist predators and their biological control potential. Overall, we found that the reference system with maize continuous monoculture and conventional crop management had the lowest activity of generalist predators compared in particular to the low‐input mixed cropping systems. Higher activity density and biocontrol potential were found in the systems that provided a dense and permanent vegetation cover of the ground (i.e., maize/sorghum, maize/flower strip). Although these effects were not consistent for all the parameters investigated and for every sampling date, we conclude that generalist predators can benefit from more conservative management practices in maize systems, thereby enhancing their biological pest control potential. Furthermore, spatial intercropping may represent a valid alternative to the conventional monocultural crop system to support the delivery of biodiversity‐mediated ecosystem services towards a more sustainable system.

Eco-efficiency analysis of rainfed and irrigated maize systems in Bosnia and Herzegovina

Abstract This study evaluated the eco-efficiency of rainfed and irrigated maize production in Bosnia and Herzegovina. Environmental impact assessments were performed through energy, carbon footprint, and water scarcity footprint analysis. For economic analysis, gross and net returns and benefit–cost ratios were calculated. Eco-efficiency was measured by the ratio between the net return and environmental criteria. The findings indicate that the transition from rainfed to irrigated maize cultivation per unit of land results in a 53.7% higher yield and gross value of production, but also a 69.8% increase in energy input, a 22% rise in greenhouse gas emissions, and a 3.6-fold increase in the water scarcity footprint. While a positive link exists in irrigated maize between higher yield and lower carbon footprint per unit of product, rainfed systems outperform in energy efficiency, productivity, profitability, water scarcity footprint, and overall eco-efficiency. Both systems rely heavily on nonrenewable energy sources, with fertilization (affecting energy and carbon footprint), mechanization (affecting carbon footprint), and irrigation (exacerbating water scarcity) as the main contributors to the negative environmental impacts. The implementation of optimization strategies for these inputs is of paramount importance to reduce environmental impacts and promote sustainability in maize farming in Bosnia and Herzegovina.

Cleaner tillage and irrigation options for food-water-energy-carbon synergism in wheat−maize cropping systems

The conventional wheat−maize systems in the North China Plain are energy and water intensive with high carbon emissions. It is imperative to find cleaner production technologies for sustainable food-water-energy-carbon synergism. Here, a three-year field experiment was performed to explore the effects of two tillage modes and four irrigation regimes during wheat season on crop yield, economic profile, water use efficiency, energy utilization, and carbon footprint in typical wheat–maize cropping systems in the North China Plain. Pre-sowing irrigation resulted in the lowest crop yield and benefit profile. Pre-sowing + anthesis irrigation decreased economic benefit and water use efficiency with higher carbon footprint. Pre-sowing + jointing + anthesis irrigation led to the greatest energy consumption and greenhouse gas emissions. However, pre-sowing + jointing irrigation increased yield by 2.3–8.7%, economic benefit by 4.0–11.1%, water use efficiency by 7.4–10.9%, and net energy by 6.5–12.0% but reduced carbon footprint by 9.8–14.3% compared to pre-sowing + anthesis irrigation and pre-sowing + jointing + anthesis irrigation. The corresponding metrics in rotary tillage improved by 9.6%, 13.9%, 7.0%, and 14.2%, respectively, relative to subsoiling, whereas carbon footprint decreased by 12.4–17.2%. Besides, rotary tillage coupled with additional jointing irrigation obtained the highest value based on a Z-score method, which was recommended as a cleaner management practice to improve benefit return and water use efficiency with lower energy consumption and carbon footprint. This work provides valuable insights into food-water-energy-carbon nexus for ensuring food security and achieving environmental sustainability in the wheat−maize cropping systems.

Potential of melatonin in enhancing antioxidant defense system and yield of maize (Zea mays L.) hybrids under saline condition

Melatonin is a multi-signaling plant hormone that significantly regulate plant growth and development under stress environment. Since a very few crop species have been investigated to disclose the role of exogenously applied melatonin on salt stress, in the current experiment, we investigated the effects of melatonin application by measuring the growth, physio-biochemical and yield attributes of two maize hybrids (2225 and 8711) in saline field (8.9 dS m−1) with two levels of melatonin (0.5 and 1.0 mM). Maize plants from both hybrids grown in saline field show reduced plant growth, fresh and dry biomass, low water contents, grain yield, reduced activities of antioxidant enzymes and poor K+/Na+ ratio due to higher Na+ influx and reduced potassium uptake by plant roots. Our results revealed that foliar application of melatonin at 1.0 mM level on salt stressed maize seedlings alleviated salt induced reduction in plant height, chlorophyll and water contents, reduced the production of proline contents and antioxidant stress indicators (malondialdehyde and hydrogen peroxide contents) and increase cob length along with improved activities of antioxidant enzymes and nutrients concentration in maize grain. Moreover, it was noticed that maize hybrid 2225 show improved growth and eminently responded to melatonin application under all treatments as compared to maize hybrid 8711. The results of the current experiment exhibit the potential of melatonin in mitigate the hazardous effects of salt stress on maize and our findings can provides scientific information for the researchers working on saline agriculture to disclose the potential benefits of melatonin application in achieving sustainable production from salt affected soils.

Accumulation and Transport of Phthalic Acid Esters in the Soil-Plant System of Agricultural Fields with Different Years of Film Mulching

In this study, we investigated the accumulation and transport patterns of phthalate ester (PAEs) compounds in the soil-plant system of maize and cabbage fields under different film mulching years. The total content of five PAEs in the maize fields soil ranged from 156.19 to 566.1 μg kg−1 with film mulching for 0–20 years. The total content of five PAEs in the cabbage field soils ranged from 252.48 to 559.07 μg kg−1 with film mulching for 0–30 years. The PAEs content in cabbage and maize field soils was lower than the environmental quality standards for soil (GB 15618-2008). With the increase in film mulching years, both maize and cabbage soil PAEs contents increased significantly (p < 0.05), while among the five PAEs, the contents of di-n-butyl phthalate (DnBP) and di(2-ethylhexyl) phthalate (DEHP) increased the most significantly, and the content of DEHP in the soils was the highest. The DEHP content in soils planted with maize ranges from 134.03 to 406.79 μg kg−1 with the film mulching for 20 years; while in soil planted with cabbage, it ranges from 229.35 to 405.2 μg kg−1 with the film mulching for 30 years. The DEHP content in all of the soils has not exceed the limit value established by the USEPA in U.S. Five PAEs were detected in maize seeds and cabbage leaves, among which the DEHP content exceeded the maximum residue limit set by the National Food Safety Standard (GB 9685-2016) for DEHP in food after more than 10 years of mulching. The bioaccumulation and translocation factors in cabbage showed a significant positive correlation with the film mulching years. However, the bioaccumulation factor and translocation factor in maize have weak correlations with the film mulching years, possibly due to the lower PAEs content in the deep soil layers where maize roots are distributed. Our research revealed a significant association between the presence and distribution of PAEs in crops and mulching years. These novel discoveries provide fundamental information for controlling PAEs pollution in agricultural environments.