Conventional Maize Research Articles

Conventional and Molecular Improvement of Maize for Drought Tolerance: Research Review

Maize (Zea mays L.) is an important staple crop for food, feed, and industry globally. Despite the importance of maize as a principal food crop in developing countries, drought is a major constraint that affects maize production, particularly in Sub-Saharan Africa, where maize is grown under rainfed conditions. Plant breeders have been striving to improve and develop drought-tolerant crops. Nevertheless, these efforts still cannot meet the demand for food security due to fast population growth and climatic change. Conventional maize breeding for drought tolerance follows a diverse approach that includes recurrent selection, backcrossing, pedigree breeding, and subsequently evaluating inbred lines and hybrids at optimum conditions, a managed screening site, and random stress across multiple environments. Molecular markers were used to select donor parents with drought-adaptive alleles and then integrated into elite maize lines to create a new population of drought-tolerant inbred lines.

Integrated crop management for long-term sustainability of maize-wheat rotation focusing on productivity, energy and carbon footprints

Modern agriculture, driven by diesel-fed machinery, is both energy and carbon-intensive, primarily due to the improper use of inputs. Designing a production module with lower carbon emissions, greater productivity, and enhanced energy use efficiency is crucial for achieving the environmental sustainability. Conservation agriculture based integrated crop management (ICMs) practices have shown promise in improving the productivity, energy-use, and reducing the carbon emissions. In our extensive long-term field study, we explored the crop yields, energy use, and carbon linkages of a maize-wheat rotation under different ICMs practices. Eight ICMs were evaluated over the course of nine consecutive years, which included ICM1&2: conventional (CT) flat-bed maize and wheat, ICM3&4: CT raised bed maize fb wheat without residues, ICM5&6: conservation agriculture (CA)-based double zero tilled (ZT) maize fb ZT wheat with residues and ICM7&8: CA-based triple ZT maize and wheat with residues and green manures. Our results indicated that the system productivity under CA-based ICMs was 16.5–22.9% greater than that under the CT-based ICM1-4. CA based ICM5-8 (125.2–131.5 × 103 MJ ha−1) needed higher energy input than CT-based ICM1-4 (32.7–39 × 103 MJ ha−1), with 76–80% shared by renewable crop residues. Furthermore, the CA-based ICMs recorded significantly higher levels of specific energy, human energy profitability, non-renewable energy use efficiency, and nutrient energy use efficiencies compared to CT-based. Likewise, the CA-based ICMs produced 12.5% more total output energy than the CT-based ICMs. In contrast, the CT based ICMs demonstrated, energy productivity, higher net energy returns and energy profitability. Compared to conventional ICMs, CA-based ICMs produced a 23–36% reduction in spatial carbon emissions and a 31–44 % reduction in yield-scale emissions. Nevertheless, the CA-based practices recorded the higher C- output, C- sustainability and C- efficiency ratio. Greenhouse gas intensity (GHGI) was 33.3–76.2% greater with the ICM1-4 practices than with the ICM5-8 practises. Thus, the present study proposed that adopting the integrated crop management practices based on the conservation agriculture could prove to be productive, as well as carbon and energy-use efficient approach for the maize-wheat rotation. This approach is envisioned to make substantial contributions to both food security and environmental sustainability.

Short‐statured maize achieved similar growth and nitrogen uptake but greater nitrogen efficiencies than conventional tall maize

AbstractDespite a historical favoring of robust tall plants in maize (Zea mays L.) production systems as a potential indicator of increased total and/or grain biomass yields, short‐statured maize is receiving renewed commercial attention in North America. Little is known of the relative N efficiencies resulting from potential inter‐stature differences in dry matter formation and N processes during pre‐ and post‐silking stages. To investigate this, two field rainfed experiments were conducted in West Lafayette, IN. The experiments included factorial combinations of two tall‐ and two short‐statured maize hybrids subjected to three N rates: 0 (unfertilized), 168 (moderate), and 224 kg N ha−1 (elevated) applied at planting. Short hybrids with a 25% reduced stature showed no statistically significant differences in seasonal biomass accumulation and N uptake, or in biomass partitioning to grain (harvest index) versus stover at maturity relative to conventional tall hybrids. Increased leaf biomass and ear growth at silking, plus comparable quantities of N remobilization from stems during grain filling, with short‐stature maize contributed to its grain yield parity with tall‐stature maize. Additionally, our research revealed other noteworthy findings: short‐statured maize had higher N harvest index and N recovery efficiency than the tall maize, implying more N status resiliency at moderate N rates. The lack of interactions between N × stature in most studied traits suggests that short hybrids can perform at least as well as conventional tall hybrids across a range of N rates. Our findings provide insights for fine‐tuning of breeding and management programs.

Agrobacterium-mediated Transformation of Tropical Maize Using Seedling Leaf Whorl Explants

Conventional maize transformation has largely relied on immature embryos as explants, and is thus often hampered by the limited access to high-quality immature embryos year-round. Here, we present a detailed protocol using seedling leaf whorls as alternative explants for tropical maize inbred transformation. This approach involves the use of a cassette that drives the expression of the morphogenic transcription factors (MTFs)Baby boom(Bbm) andWuschel2(Wus2), which have been shown to greatly enhance transformation efficiency. We outline here the steps required for the preparation of seedling leaf whorl explants and subsequentAgrobacteriuminfection, and describe the tissue culture regimen that results in transgenic plant regeneration. Because constitutive expression ofBbmandWus2prevents normal plant regeneration and the production of fertile plants, the cassette containing these genes must be excised. As such, we include the steps for theCre/loxP-mediated excision of the MTF gene cassette. The protocol outlines a year-round, more affordable, and efficient approach for carrying out maize transformation for crop improvement.

Millets and sorghum as promising alternatives to maize for enhancing climate change adaptation strategies in the Mediterranean Basin

ContextClimate change is increasingly requiring the adoption of both climate-resilient alternative crops and sustainable management practices. Millets and sorghum are increasingly recommended as alternatives to maize in addressing these issues, yet there are no studies comparing the environmental impacts of food-crop millets and sorghum with maize, under sustainable management in Mediterranean area. ObjectiveThe present study examined for the first time the environmental and economic impacts, as well as agronomic performances, of rainfed cultivated proso millet, sorghum and maize over a three-year period under challenging climatic conditions in Emilia-Romagna region, Italy. MethodsDifferent kinds of trials were realized during three years of experimentation in one location in Ravenna province. The first trial aimed to compare proso millet, sorghum and maize agronomical performances and water use efficiency in a low-input system. The second trial aimed to compare soil fertility and biodiversity impacts of two different agronomical management systems (low-input and high input) for the summer crops previously described. Soil basic fertility parameters were monitored and ground dwelling arthropods were collected and analyzed using pitfall traps. The last trial of this study intended to evaluate the environmental and economic performances of the previous cereal crops cultivated in the low-input and high-input systems, applying the Life Cycle Assessment (LCA) and the Life Cycle Costing (LCC) methodologies. ResultsBoth organic sorghum and millet showed high potential as viable summer-crop alternatives, not only to organic maize, based on yield, water use efficiency, disease tolerance and weed competition, but also to conventional maize, based on reduced environmental and economic impacts. Positive land impacts including improved beneficial arthropod abundances and preserved soil fertility were evident under organic management. In fact, the comparative LCA and LCC, carried out with primary data from conventionally cultivated maize and sorghum within central-north Italy and the organic experimental field under investigation, showed that the Global Warming and Eutrophication Potential, were comparable between the organically cultivated crops and significantly lower than conventional maize and sorghum. ConclusionsThe results highlighted the potential of sorghum and millet cultivation as rainfed summer-crop alternative to maize in climate-change context, especially in low-input agronomical systems. In particular, under rainfed, organic management over three years, proso millet yielded consistently. ImplicationsUnder the sustainable practices of the present study, proso millet outperformed maize for yield and WUE stability, as well as potential costs saved, related to the production amount per unit area and potential revenue.

Comparative Study of Productivity of Organic and Conventional Agriculture in Maize Crops in East Java

This study provides a comparative analysis of the productivity of organic and conventional maize farming in East Java, employing a quantitative approach with 40 sample farms. Utilizing a Likert scale from 1 to 5, data were collected and analyzed using SPSS version 26. The findings indicate that while conventional farming demonstrates higher average yields, the difference in productivity between the two systems is statistically significant but not substantial. Organic farming shows competitive productivity, particularly in the long term, due to its positive impact on soil health and sustainability. The study highlights the potential of organic farming as a viable alternative to conventional practices in maize cultivation, offering valuable insights for policymakers and farmers in East Java.

Toxic Effects of Bt-(Cry1Ab+Vip3Aa) Maize (“DBN3601T’’ Event) on the Asian Corn Borer Ostrinia furnacalis (Guenée) in Southwestern China

Asian corn borer (ACB), Ostrinia furnacalis, is an important agricultural pest affecting maize production in southwestern China, but knowledge of the toxic effect of Bt maize on the pest has been insufficient until now. In this study, we determined the susceptibility of ACB to Cry1Ab, Vip3Aa, and their complex proteins and evaluated the efficacy of Chinese domestic Bt-(Cry1Ab+Vip3Aa) maize (“DBN3601T” event) against the pest in Yunnan Province of southwestern China. The susceptible bioassay indicated that the LC50 values of the Cry1Ab and Cry1Ab+Vip3Aa proteins expressed by the Bt maize varieties against ACB larvae were 51.42 and 46.85 ng/g, respectively; however, the ACB larva was insensitive to the Vip3Aa protein. The Cry1Ab+Vip3Aa protein contents in V6–V8 leaves, VT tassels, R1 silks, R2 kernels, R3 stalks and R3 cobs of the Bt-(Cry1Ab+Vip3Aa) maize were 114.20, 30.69, 3.77, 8.92, 11.09 and 10.99 μg/g, respectively. The larval feeding test indicated that the Bt-(Cry1Ab+Vip3Aa) maize was more toxic to the early instar larvae, and the survival time of larvae fed on the leaves was the shortest, while it survived the longest on stalks. The identification of maize resistance levels in the field showed that both larval density and plant damage score of Bt-(Cry1Ab+Vip3Aa) maize were significantly lower than those in conventional maize. It is concluded that the Bt-(Cry1Ab+Vip3Aa) maize can be used for control of the ACB in southwestern China.

Resistance of Transgenic Maize Cultivars to Mycotoxin Production-Systematic Review and Meta-Analysis.

Approximately 25% of cereal grains present with contamination caused by fungi and the presence of mycotoxins that may cause severe adverse effects when consumed. Maize has been genetically engineered to present different traits, such as fungal or insect resistance and herbicide tolerance. This systematic review compared the observable quantities, via meta-analysis, of four mycotoxins (aflatoxins-AFL, fumonisins-FUM, deoxynivalenol-DON, zearalenone-ZEA) between genetically modified (GM) and conventional maize kernels. This study was conducted following the PRISMA guidelines, with searches performed using PubMed, Web of Science, Scopus, Google Scholar, and CAPES journals databases. Analyses were conducted using RevMan v.5.4 software. Transgenic maize showed a 58% reduction in total mycotoxins (p < 0.001) compared to conventional maize. FUM were the most impacted, with a 59% reduction (p < 0.001) in GM maize. AFL and ZEA levels were also lower in GM maize by 49% (p = 0.02) and 51% (p < 0.001), respectively. On the other hand, DON levels increased by 6% (p < 0.001) in GM maize compared to conventional maize. However, results for ZEA and DON were inconclusive due to the limited research and sample sizes. We conclude that transgenic maize reduces total mycotoxins by over 50%, primarily fumonisin and aflatoxin. Most studies presented maize varieties that were resistant to insects or herbicides, not fungal pathogens, showing a positive collateral effect of these genetic alterations. Therefore, transgenic maize appears to be a safer product for animal and human consumption from a toxicological point of view. Further studies with larger sample sizes are needed to confirm our findings for ZEA and DON in transgenic maize.

Effects of thermophilic and acidophilic microbial consortia on maize wet-milling steeping

To understand the ecology of species and promote biotechnology through beneficial strain selection for improving starch yield in maize wet-milling steeping, bacterial diversity and community structure during the counter-current steeping process in a commercial steeping system were characterized and investigated. The microbial diversity in the steeping liquor, which consisted of 16 phyla, 131 families, and 290 genera, was more abundant compared to those present on the surface of unsteeped maize. As the counter-current steeping progressed, exposing newer maize to the older steepwater, Lactobacillus dominated, replacing Rahnella, Pseudomonas, Pantoea, and Serratia. The thermophilic and acidophilic microbial consortia were enriched through adaptive evolution engineering and employed to improve starch yield. Several steeping strategies were evaluated, including water alone, SO2 alone, mono-culture of B. coagulans, microbial consortia, and a combination of consortium and SO2. Combining the microbial consortium with SO2 significantly increased the starch yield to, about 66.4 ± 0.5%, a 22% and 46% increase over SO2 alone and the consortium alone, respectively. Scanning electron microscope (SEM) of steeped maize structure indicated that the combination of consortium and SO2 disrupted the protein matrix and widened gaps between starch granules in maize endosperm. This released proteins into the steepwater and left starch granules in the aleurone layer. The steeping strategy of using thermophilic and acidophilic microbial consortium as additives shows potential application as an environmentally friendly alternative to conventional maize steeping procedures.

Sub-surface drip fertigation of nitrogen coupled with crop residue incorporation enhanced the growth and yield of maize in an alluvial soils

A two-year field experiment was conducted at ICAR-Indian Agricultural Research Institute, New Delhi, to standardize the N-fertigation schedule and crop residue management in sub-surface drip fertigated (SSDF) maize [Pusa HQPM 1’ improved: double bio-fortified]. The experiment was laid-out in a split-plot design with 3 replications. There were 8 main-plot treatments comprising different N sub-surface drip fertigation levels (0, 50, 75, 100% RDN) with one conventional cultivation of maize, where RDN (150 kg/ha) was applied as per recommendation. Under sub-surface fertigation of N, each dose of N was divided into 3-and 4-splits, for fertigation. Sub-plot treatments included greengram residue (3 t/ha) and no greengram residue incorporation. P and K (60 kg P2 O5 /ha and 40 kg K2 O/ha respectively) fertilizers were supplied equally in all the plots by SSDF. Results revealed that plant height at various stages statistically varied with levels and splits of SSDF-N and crop residue incorporation. The highest plant height and leaf area were recorded with 100% RDN-4S which remained at par with 100% RDN-3S and 75% RDN-4S. Conventional maize cultivation was inferior to ‘RDN100’ and 75%, however on par with 50% RDN. The nitrogen uptake was found significantly superior in 100 and 75%RDN over conventional and control treatments. Similarly, the grain yield of maize was highest under 100% ‘RDN-4’ &amp;3 S, and 75% RDN-4S, which were at par with one another. Overall, it could be concluded that sub-surface fertigation of N not only improved the growth and yield of maize but also helped in 25–50% saving of valuable fertilizer.

Comparing the cost-effectiveness and yarn quality improvement with PVA versus conventional maize starch as the sizing agents

The clothing industry is striving to reduce material use and energy consumption during the production process to maximize resource efficiency. The production of high-quality fabrics is driven by key materials such as sizing agents. While starch and its derivatives stand as the most prevalent natural sizing agents, they are without their drawbacks, particularly during the de-sizing process. Maize starch is the most widely used sizing agent in Ethiopia’s textile sector, yet its use presents challenges both in terms of the efficiency of the weaving process and in terms of the quality of the textiles. This study focuses on the development of a new size recipe for textile fabric processing, which is exclusive to PVA synthetic sizing material. Various criteria, such as viscosity, production improvement, environment sustainability, fabric quality, ease of de-sizing, low breakage rate, and cost-effectiveness, have been considered in selecting PVA sizing agents. The study assessed parameters such as size regain, yarn elongation loss, and fabric production. The study demonstrates the potential for substantial improvements in textile production by exploiting PVA's special properties and addressing shortcomings related to traditional sizing material. This shift to PVA based sizing formulations is not only expected to improve the quality and production efficiency of the fabric, but also to meet the wider sustainability objectives of the textile industry.

Discrimination of maize transgenic and non-transgenic varieties by laser induced spectroscopy (LIBS) and machine learning algorithms

BackgroundIn the last decades, the production and consumption of genetically modified agricultural products have increased markedly due to the worldwide population growth and rising demand for food and feed. Consequently, genetically modified crops have been extensively produced and consumed, which required identifying and discriminating transgenic and non-transgenic products. ResultsLaser-induced breakdown spectroscopy (LIBS) combined with chemometric methods was applied to identify and discriminate two varieties of conventional (not-genetically modified, NGM) maize from four varieties of transgenic maize (genetically modified, GM). The LIBS spectra acquired under reduced pressure (100 Torr) conditions over two ranges, i.e., 175–330 nm and 275–770 nm, were subjected to Standard Normal Variation (SNV) and multivariate methods such as Principal Component Analysis (PCA) to reduce data matrices dimensionality and spectral noise. The supervised machine learning algorithms k-nearest neighbor (k-NN) and support vector machine (SVM) have been applied to discriminate among NGM and GM maize reserving 25 % of data for external validation. The training data were employed for hyperparameter optimization of classifiers using the Leave-One-Out Cross-Validation (LOOCV) method. Considering all six maize varieties simultaneously, the highest training accuracy achieved was 90.56 %, with an external validation accuracy of 88.33 %. In an alternative approach based on pairwise combinations of one GM variety against one NGM variety, the best outcome achieved was 100 % LOOCV and external validation accuracy. ConclusionsThese results showed that LIBS supported by appropriate chemometric methods represents an alternative screening technique for identifying and discriminating transgenic from non-transgenic maize.

Maize Kernel-Associated Metagenomes Reveal Potential Microbe–Microbe Interactions that Underlie Fusarium Ear Rot Disease

As an alternative to host resistance, transgenic expression of entomocidal and antimicrobial proteins from Bacillus thuringiensis ( Bt) in maize can mitigate Fusarium ear rot (FER). This study evaluated FER in Bt and conventional maize and the role of microbes in the kernel-associated metagenome using quantitative reduced representation sequencing. Our results revealed significant differences in FER severity across environments and varieties and between inoculation treatments. The lower FER scores of conventional maize Spectrum 6416 relative to other varieties highlighted resistant alleles in maize germplasm, whereas strong correlations indicated FER-induced yield loss. Mitigation of FER by transgenes was validated by about threefold enrichment of Fusarium verticillioides ( Fv) postinoculation compared with nonsignificant Fv enrichment in conventional maize. Although the major causal pathogen of FER, Fv, was the most abundant species in the metagenomes ( r = 0.41 to 0.49), a similar degree of correlation was observed between FER and several Fusarium spp. ( r = 0.2 to 0.56). The potential FER-suppressing properties of Talaromyces stipitatus and Ustilago maydis were indicated by negative correlations with FER ( r = –0.22 to –0.42), Fv, and some Fusarium spp. The more FER-resistant varieties consistently enriched for potential FER-suppressing Burkholderia cenocepacia (negatively correlated with Fv). This suggests host genetic background-dependent recruitment of beneficial microbes that suppress pathogens and that microbe–microbe interactions play a role in FER severity. Quantitative and species/strain-level metagenomic profiles hold promise for identifying robust disease-suppressing microbes and microbes that act in synergy with pathogens and for developing holobiont-aware breeding strategies that account for host–microbiome coevolution and host genotype, microbiome/metagenome, and environment interactions. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

Establishment of a high-yield intercropping system for maize and legumes under rainfed conditions in eastern Bhutan

ABSTRACT Maize-legume intercropping is a sustainable strategy to improve maize production for smallholder farmers. Maize is a staple food crop in Bhutan and integration of legumes with maize has been considered as an alternative option towards enhancing maize production in the country. Here, we conducted two studies in eastern Bhutan: first study (2021) to identify suitable legumes for intercropping with maize and second study (2022) to evaluate the effects of different maize-soybean intercropping patterns on grain yield, land use efficiency, and economic benefits. The maize-soybean intercropping system showed better productivity and economic viability than the kidney bean and groundnut systems in both the sites. Row intercropping and strip intercropping with 2 rows of maize alternating with 2 rows of soybean (2 M:2S) spaced 0.3 × 0.3 m showed stable and consistently higher grain yield at Lingmethang and Wengkhar (LING = 6.05 t ha−1; WENG = 8.37 t ha−1). The land equivalent ratio (LING = 1.78; WENG = 1.73) and net return (0.16 million Nu. ha−1 for LING and 0.21 million Nu. ha−1 for WENG) were notably higher for these intercropping methods. Our results suggest that the integration of legumes between conventional maize planting density, row intercropping and strip intercropping (2 M:2S) spaced at 0.3 × 0.3 m would be beneficial for achieving higher productivity for smallholder farmers in eastern Bhutan.

Coexistence field trials between MON810 and conventional maize in Mallorca as a basis for a regional regulatory proposal based on scientific evidence in the times of genome editing

This paper reports the first coexistence field trials between transgenic and conventional maize carried out under Mediterranean island conditions. Their purpose was to assess the local validity of pollen barriers and sowing delays as coexistence strategies as a basis for a regional regulation on the subject. Two field trials were performed in two agricultural states of Alcudia and Palma, in Mallorca (Spain). In the first one, two adjacent plots were synchronously sown with conventional and transgenic maize, respectively. In the second trial, the previous design was replicated, and two additional plots sown with GM maize were added, paired with their respective conventional recipient plots sown 2 and 4 weeks later. All conventional plots were located downwind from their respective GM plots. Of the two conventional plots in sowing synchrony, only one of them required a 2.25 m pollen barrier to meet the 0.9% labeling threshold. A 4-week sowing delay between GM and non-GM plots proved to be enough to keep the GM content of the recipient plots below the legal threshold. However, with a 2-week sowing delay additional coexistence measures such as pollen barriers might be needed, as suggested in the literature. Results are consistent with previous research conducted in the northeast of Spain, thus validating in the island’s agroclimatic conditions a model successfully tested in that peninsular region which allows to accurately estimate the need and width of pollen barriers. The results presented here could perhaps be extrapolated to other islands, coastal areas, and regions with stable prevailing winds during the maize flowering season.

Conservation agriculture and weed management effects on weed community and crop productivity of a rice-maize rotation

In recent years, an increase in weed infestation, which is adversely affecting crop growth and productivity has been a major challenge facing the farmers of South Asia. The adoption of a permanent bed in combination with residue retention-based crop management practices may reduce weed abundance and increase crop productivity. In a two-year field study, we evaluated the responses of different organic weed management practices with contrasting tillage and residue (R) management strategies to weed dynamics and crop productivity under rice-maize rotation. The main plot treatments consisted of zero-tillage direct seeded rice and zero-tillage maize (ZTR fb ZTM); ZTDSR and maize both on permanent raised beds with residue (PBDSR + R fb PBDSM + R); PBDSR and PBM without residue (PBDSR-R fb PBDSM-R) and conventional tillage puddled transplanted rice and conventional tillage maize (CTR fb CTM). The subplots comprised unweeded control; vermicompost mulch; P- enriched vermicompost mulch; live mulch with Sesbania spp. in rice and Pisum sativum in maize and weed-free. Total weed density and biomass in rice and maize at 30 days after sowing (DAS) were minimum for PBDSR + R fb PBDSM + R compared to remaining tillage and residue management practices in both years. Apart from weed-free treatment, the highest weed control index was found with live mulch. Yield of rice and maize were found higher in permanent beds along with residue retention-based practices. In rice, the weed-free treatment showed the highest grain yield and live mulch reported 9.8 and 6.8 % higher grain yield than vermicompost mulch and P-enriched vermicompost mulch respectively. Our study shows that conservation agriculture practices under rice-maize rotation is one of the ways to reduce weed density and improve crop productivity in South Asia and other similar agro-ecologies.

Assessment of sustainability attributes of traditional and conventional maize cultivation in farmer agricultural systems

Objective: To carry out a comparative analysis of the sustainability of traditional and conventional maize cultivation systems in Cuanacaxtitlán. Design/Methodology/Approach: The proposal was implemented through a mixed method approach in which a qualitative research predominated. A sustainability assessment for the 23 farmer systems of maize production in Cuanacaxtitlán was carried out, according to the Indicator-Based Sustainability Assessment Framework (Marco para la Evaluación de Sistemas de Manejo Incorporando Indicadores de Sustentabilidad: MESMIS). Results: The sustainability level between the two types of agroecosystems does not differ much. According to the chosen indicators, TMS is more sustainable in the environmental and economic aspect, while CMS is more sustainable in the social aspect. The average profitability of TMS is better as a result of the milpa profits. Study Limitations/Implications: Family Production Units (FPUs) do not own their lands, which limits the improvement of profitability and sustainability in maize production. To this end, land distribution or support programs for landless farmers is important. Findings/Conclusions: Among the 23 systems under analysis, critical values were obtained for two environmental indicators: fertilizer application and pesticide use. Therefore, improving the use of these inputs is an important task.

Insecticidal Effects of Transgenic Maize Bt-Cry1Ab, Bt-Vip3Aa, and Bt-Cry1Ab+Vip3Aa against the Oriental Armyworm, Mythimna separata (Walker) in Southwest China.

The oriental armyworm, Mythimna separata (Walker), an important migratory pest of maize and wheat, is posing a severe threat to maize production in Asian countries. As source areas of spring-summer emigratory populations, the control of M. separata in southwestern China is of great significance for East Asian maize production. To assess the toxicity of Bt maize against the pest, bioassays of Bt-(Cry1Ab+Vip3Aa) maize (event DBN3601T), Bt-Cry1Ab maize (event DBN9936), and Bt-Vip3Aa maize (event DBN9501) were conducted in Yunnan province of southwest China. There were significant differences in insecticidal activity between the three Bt maize events, and DBN3601T presented the highest insecticidal role. The results also indicated that the insecticidal effect of various Bt maize tissues took an order in leaf > kernel > silk, which is highly consistent with the expression amounts of Bt insecticidal protein in leaf (69.69 ± 1.18 μg/g), kernel (11.69 ± 0.75 μg/g), and silk (7.32 ± 0.31 μg/g). In field trials, all larval population densities, plant damage rates, and leaf damage levels of DBN3601T maize were significantly lower than the conventional maize. This research indicated that the DBN3601T event had a high control efficiency against M. separata and could be deployed in southwest China for the management of M. separata.

Toxic Effects of Bt-(Cry1Ab+Vip3Aa) Maize on Storage Pest Paralipsa gularis (Zeller).

Paralipsa gularis (Zeller) is a storage pest; however, in recent years it has evolved into a considerable maize pest during the late growth stage in the border region between China and other Southeast Asian countries. Bt transgenic insect-resistant maize is an effective measure in controlling a wide range of lepidopteran pests, but there is a lack of research on the toxic effects of storage pests. We tested the toxicity of Bt-Cry1Ab, Vip3Aa, and their complex proteins against P. gularis via bioassay and investigated the efficiency of Bt-(Cry1Ab+Vip3Aa) maize in controlling P. gularis during the late growth stage of maize in the period 2022-2023. The bioassay results show that the susceptibilities of P. gularis to the two Bt proteins and their complex proteins were significantly different. The LC50 values of DBNCry1Ab ("DBN9936" event), DBNVip3Aa ("DBN9501" event), DBN Cry1Ab+Vip3Aa ("DBN3601T" event), and Syngenta Cry1Ab+Vip3Aa ("Bt11" event × "MIR162" event) were 0.038 μg/g, 0.114 μg/g, 0.110 μg/g, and 0.147 μg/g, and the GIC50 values were 0.014 μg/g, 0.073 μg/g, 0.027 μg/g, and 0.026 μg/g, respectively. Determination of the expression content of the insecticidal protein in different tissues of Bt-(Cry1Ab+Vip3Aa) maize shows that the total Bt protein content in different tissues was in the following order: stalk > bract > cob > kernel. However, the bioassay results show that the mortalities of P. gularis feeding on Bt-(Cry1Ab+Vip3Aa) maize in different tissues at different growth stages were all above 93.00%. The field trial indicates that the occurrence density of larvae and plant damage rate for conventional maize were 422.10 individuals/100 plants and 94.40%, respectively, whereas no larvae were found on Bt-(Cry1Ab+Vip3Aa) maize. In summary, this study implies that Bt-(Cry1Ab+Vip3Aa) maize has a high potential for control of P. gularis, providing a new technical measure for the management of the pest.

Effect of Legumes Intercropped with Maize on Biomass Yield and Subsequent Biogas Production

The presented study deals with the use of legumes intercropped with maize for the production of biogas from silage. The main goal was to find out whether silages made from mixed cultures can be used in biogas production and how the use of such silages affects qualitative and quantitative parameters of the fermentation process compared with the pure maize silage. Variants prepared were pure cultures of maize, bean, lupin, and white sweet clover. In addition, mixed cultures were prepared of maize and individual legumes. Measured values showed that in terms of dry matter (DM) yield, mixed culture silages are almost of the same or even better quality than silage made from the maize monosubstrate. Compared with the maize monoculture silage, the presence of white lupine, white sweet clover, and broad bean in silages statistically significantly increased the content of DM, ash, and acid detergent fiber (by more than 5%). Bean and lupine in mixed silages with maize significantly increased the content of lipids (on average by more than 1.2%). Legumes in silages were significantly decreasing contents of neutral detergent fiber, crude protein, and starch. Production of biogas from silages of maize monosubstrates and mixed substrates of maize with white lupin, maize with white sweet clover, and maize with broad bean was directly proportional to the content of CAR and starch in these substrates. A perspective variant was the mixed substrate of maize and sweet clover from which biogas production was only 6% lower than that from conventional maize silage. The highest yield was recorded in the maize monosubstrate (0.923 m3/kgVS). Variants of mixed substrates had a yield ranging from 0.804 to 0.840 m3/kgVS.