Maize Conservation Research Articles

Efficacy of Zerofly® hermetic and polypropylene storage bags for conservation of maize in layer poultry farms in Ghana

Efficacy of Zerofly® hermetic and polypropylene storage bags for conservation of maize in layer poultry farms in Ghana

Cytogenetics of maize in Mexico as a field of transnational exchange: The case of Takeo Ángel Kato Yamakake

Societal Impact StatementMaize is one of the most consumed grains worldwide. Its production and international trade are expected to continue increasing because of its use as animal fodder and direct human food. Although maize's history spans millennia, in the last century it underwent significant changes due to genetic engineering, particularly during the Green Revolution. Due to maize's importance for current food security and energy production, it is fundamental to understand this engineering process to assess the implications of current styles of maize production for local and global landscapes, scientific institutions, and transnational networks of agricultural science.Summary This article aims to explain how Mexican agricultural expertise contributed to the development of cytogenetics as a specialized field in the study of the diversity of maize within the framework of the Green Revolution. To this end, the article follows the work of Mexican agronomist Takeo Ángel Kato Yamakake within the activities of the Inter‐American Maize Improvement Program (IMIP), formally established in 1960. By reconstructing the debate on the genetic implications of chromosomal structure and function, this study contributes to the historiography devoted to the role played by local experts in the classification, experimentation, and conservation of maize. The article is based on sources from Mexico and the United States, an interview with Kato, and the consultation of the database “Rockefeller Fellows. Individual Mobility Awards at Rockefeller‐endowed Organizations, 1914‐1970.” Kato's trajectory provides an overview of agronomy in Mexico and shows the relevance of transnational exchange in the establishment of plant cytogenetics. Kato's academic activity features collaborations with key figures such as Edwin Wellhausen, Albert Longley, Barbara McClintock, W. Gallinat, Czeslawa Prywer, and Almiro Blumenschein. A Green Revolution era quest to unravel the origin of maize as a way of perfecting its genetic manipulation fueled the interest in establishing cytogenetics in Mexico. However, the irruption of the molecular approach made the study of the position of chromosomal knobs less of a priority. Despite this, classical cytogenetics, under Kato's leadership, remains a field that contributed to the knowledge of the vegetal genome, even when the IMIP disappeared and the logic of the Green Revolution lost its centrality.

Effects of no-tillage and different stover mulching amounts on soil microbial community and microbial residue in the Mollisols of China.

To investigate the effects of no-tillage and different amounts of stover mulch on soil microbial community composition and their residues, we set up a field experiment of different amounts of stover mulch under no-tillage on the long-term maize conservation tillage station located in the Mollisols area of Northeast China (built in 2007), including without stover mulch (NT0), 1/3 stover mulch (NT1/3), 2/3 stover mulch (NT2/3) and full stover mulch (NT3/3), and the conservation tillage (plowing without stover mulch, CT) as control. We analyzed phospholipid fatty acid, amino sugar biomarker and soil physicochemical properties at different soil layers (0-5 cm, 5-10 cm, 10-20 cm). The results showed that compared to CT, no-tillage without stover mulch (NT0) did not affect soil organic carbon (SOC), total nitrogen (TN), dissolved organic carbon and nitrogen (DOC, DON), water content, microbial community and their residue. The main effects of no-tillage and stover mulch were found in the topsoil. Specifically, the NT1/3, NT2/3 and NT3/3 significantly increased SOC content by 27.2%, 34.1% and 35.6%, respectively, phospholipid fatty acid content was significantly increased under NT2/3 and NT3/3 by 39.2% and 65.0%, respectively, and NT3/3 significantly increased the content of microbial residue-amino sugar by 47.2% in the depth of 0-5 cm compared with CT. The variations in soil properties and microbial community induced by no-tillage and different amounts stover mulch decreased with soil depth, with almost no difference in the 5-20 cm soil layer. SOC, TN, DOC, DON, and water content were the main factors influencing the composition of the microbial community and the accumulation of microbial residue. Microbial biomass was positively correlated with microbial residue, particularly fungal residue. In conclusion, all stover mulch treatments promoted SOC accumulation to different degrees. When there is sufficient stover, it is advisable to opt for no-tillage with full stover mulch, as it is most conducive to the increases of soil microbial biomass, microbial residue and SOC. In case when the amount of stover is inadequate, however, no-tillage with 2/3 stover mulch can still improve soil microbial biomass and SOC content. This study would provide practical guidance for stover management in conservation tillage and sustainable agricultural development in the Mollisols area of Northeast China.

A data mining approach gives insights of causes related to the ongoing transgene presence in Mexican native maize populations

ABSTRACT Mexico is the center of origin of maize and one of the phenomena that imperil maize conservation is transgene presence. Although previous studies have documented transgene presence in Mexican landraces, to date there is no countrywide transgene monitoring protocol, nor systematic analyses assessing which factors could be related with transgene presence and dispersal. In this work, we propose a geographically representative sampling protocol and present empirical data from three sampled states: Mexico City, Oaxaca and Chiapas. To further investigate which environmental and social variables could be associated with transgene presence, we carried out a data mining approach. To assess transgene presence in collected maize samples, we used Real-Time PCR, finding that transgenes were widely distributed across sampled localities: 33% of the localities in Chiapas, 25% in Mexico City and 11% in Oaxaca. The data mining approach allowed us to identify state-specific spatial associations in Chiapas and Oaxaca. In Chiapas, a higher probability of transgene presence appeared related to the coexistence of industrialized maize agriculture, while in Oaxaca it was related with seed exchange. We discuss the importance of implementing a national biomonitoring protocol to increase our understanding of the sources that enable transgene presence and dispersal.

Effect of Maize Conservation Crops Associated with Two Vegetal Covers on the Edaphic Macrofauna in a Well-Drained Savanna of Venezuela

Conventional agricultural in the Venezuelan Llanos has generated gradual soil degradation. Therefore, conservationist agriculture has been proposed. According to several works, this type of management favors soil macrofauna. To test this hypothesis, the response of soil macrofauna to the establishment of conservationist maize crops, associated with Brachiaria dictyoneura (Bd) and Centrosema macrocarpum (Cm), was evaluated. The samples of soil and soil macrofauna were taken per vegetation cover at different climatic season over 2 years and 10 months. For this period and under the conditions studied, the results partially refute the hypothesis; on the one hand, they showed that the soil macrofauna of a natural savanna (NS) is the most diverse and equitable (N1 = 4.5 ± 2.8), followed by the cultivation of maize associated with Cm (N1 = 3.2 ± 1.9) and the least diverse with Bd (N1 = 2.6 ± 2.1). Additionally, some taxonomic groups apparently did not tolerate soil intervention, while Termitidae was favored. On the other hand, the temporal variation of the soil macrofauna did not differ between vegetation covers (F: 1.18; p = 0.37). This variation could be due to the decrease in TP (r = −0.55) and increased BD (r = 0.56).

Transgene Flow: Challenges to the On-Farm Conservation of Maize Landraces in the Brazilian Semi-Arid Region.

Brazil is one of the largest global producers of genetically modified crops and a center of origin and diversification of relevant species for agriculture and food. Transgenic monocultures occupy around 50 million hectares, whereas smallholder farmers, indigenous people, and traditional communities are responsible for in-situ/on-Farm conservation of local genetic resources. Based on 15 years of expertise in regulating GMOs and in cross-institutional agrobiodiversity conservation projects, this article discusses the challenges regarding the coexistence of these two agricultural models based on transgene flow detection in maize landraces. As part of a broad and unique participatory transgene-flow-monitoring process, 1098 samples of maize landraces were collected in the Brazilian Semi-arid Region between 2018 and 2021 and analyzed using immunochromatographic strips. The tests revealed 34% of samples with presence of GM proteins. It is concluded that the biosafety standards in force in Brazil do not allow the assurance of on-Farm conservation of maize. The sectors that contribute to agrobiodiversity conservation and do not benefit from using GM seeds are taking on the burden of this process. Transgene flow can be reduced by approving and enforcing more effective coexistence rules that consider maize landraces crop areas also as seed-producing areas added to full disclosure of commercial seeds origin.

Perspectives on native maize conservation in Mexico: a public programme analysis

SummaryIn any conservation programme, a variety of actors participate and interact in its different phases. They commonly have different perspectives and priorities regarding conservation, and diversity in the ensuing perspectives constitutes a barrier to effective conservation. In this paper, we analyse the different perspectives around thePrograma de Conservación de Maíz Criollo(Programme for the Conservation of Native Maize in Mexico; PROMAC) in order to understand the possible causes that resulted in the programme not fulfilling its objectives. We used Q methodology and semi-structured interviews with farmers from a natural protected area to analyse the perspectives of the key actors who conceptualized, designed and implemented the programme and of the target population. Our research identified two different perspectives: (1) native maize can only be conserved with the support of community processes; and (2) the government, and not farmers, is responsible for the conservation of native maize. For farmers, native maize is key to their subsistence livelihoods, and they participated in the programme because of government monetary incentives. These differences contributed to dissimilar interpretations throughout the programme’s implementation phase, which, in turn, likely contributed to PROMAC failing to meet its objectives.

Bridging different perspectives for biocultural conservation: art-based participatory research on native maize conservation in two indigenous farming communities in Oaxaca, Mexico

Native maize conservation rests on the custody of traditional and indigenous small-scale farmers, but their traditional practices and way of life are challenged by multiple forces associated with globalization, international trade and neoliberal agricultural policies. Through participatory art-based research with two indigenous communities in Oaxaca, Mexico, we identified the main challenges and strategies for native maize conservation, as perceived by these farming communities. We implemented a stepwise method to elicit local strategies for biocultural conservation pertinent across gender and generations. We conclude that understanding the heterogeneity of perspectives is important for identifying root causes of agrobiodiversity decline and strategies for biocultural native maize conservation.

Impact of maize conservation agricultural system on nitrogen losses through surface runoff and soil erosion in dryland

Nutrient loss in dry land through surface runoff and soil erosion is thought to dominate the watershed eutrophication. Conservation agriculture is expected to be able to reduce the nitrogen (N) loss into river systems. This study aimed to compare the N total input between conservation and conventional farming systems and to analyze N losses through surface runoff and soil erosion in conservation agriculture compared to conventional farming systems. The study was conducted at Agro-Techno-Park at Jatikerto, Brawijaya University from December 2017 to September 2018. The experiment was designed with three factors, i.e. (1) with and without biogeotextile, (2) No and conventional tillage, (3) application of four kinds of cover crop residues, with three replications. Results of the study showed that conservation agriculture was able to provide higher N inputs into the soil than conventional agriculture. The N loss through surface runoff was relatively low, ranging from 0.03 kg/ha to 0.45 kg/ha. N loss through erosion with conventional tillage and without biogeotextile reached 15 kg/ha to 32 kg/ha. No-tillage practices combined with the biogeotextile application significantly reduce N losses through soil erosion to only 0.3 kg/ha to 5 kg/ha. Conservation agriculture is one of the solutions to overcome the trade-off between the need for increased food production and environmental protection.

Maize (Zea mays L.) management in Yaxcaba, Yucatan, during the twentyfirst century’s first decade is consistent with an overall loss of landrace diversity in southeast Mexico

The status of genetic resource conservation in centers of crop diversity remains disputed. Recent case-study findings of persistent maize diversity in Yaxcaba, Yucatan, a municipality in southeast Mexico, have raised questions on earlier reports of widespread losses across the crop’s center of diversity in Mexico. We break down patterns in maize varietal richness in southeast Mexico to show that temporal trends in Yaxcaba are subsumed under spatial variation in this broader region and consistent with an overall loss of diversity. Persistence of diversity in Yaxcaba can be explained by conditions that allowed subsistence farmers to continue sowing land even as maize prices dropped, but these conditions may be rare in Mexico and likely to change. Yaxcaba emerges as a rare community of exceptional diversity from which valuable policy lessons can be drawn. We find that gaps and omissions in the Mexican Government’s strategy for maize conservation have excluded Yaxcaba and likely resulted in an ineffective intervention elsewhere in the Peninsula. An integrated-systems perspective should help us develop a coherent strategy for resource conservation and climate adaptation based on more efficient and equitable instruments.

Genetic resources in maize breeding

Maize, wheat and rice are the most important cereals grown in the world. It is predicted that by 2025 maize is likely to become the crop with the greatest production globally. Conservation of maize germplasm provides the main resources for increased food and feed production. Conservation in gene banks (ex-situ) is dominant strategy for maize conservation. More than 130 000 maize accessions, e.g. about 40% of total number, are stored in ten largest gene banks worldwide and Maize Research Institute Zemun Polje (MRIZP) gene bank, with about 6000 accessions, is among them. Organized collecting missions started in 1961. in the former Yugoslavian territory, and up today, more than 2000 local maize landraces were stored. Pre-breeding activities that refer to identification of desirable traits from unadapted germplasm within genebank, result in materials expected to be included in breeding programs. Successful examples are LAMP, GEM and GENRES projects. At the end of XX century, at MRIZP genebank two pre-breeding activities were undertaken: eco-core and elite-core collections were created and landraces fulfilled particular criteria were chosen. In the last decade, MRIZP genebank collection was used for identification of sources for drought tolerance and improved grain quality. According to agronomic traits and general combining ability, two mini-core collections were created and included in commercial breeding programs.

The Development of Quality Control Genotyping Approaches: A Case Study Using Elite Maize Lines

Quality control (QC) of germplasm identity and purity is a critical component of breeding and conservation activities. SNP genotyping technologies and increased availability of markers provide the opportunity to employ genotyping as a low-cost and robust component of this QC. In the public sector available low-cost SNP QC genotyping methods have been developed from a very limited panel of markers of 1,000 to 1,500 markers without broad selection of the most informative SNPs. Selection of optimal SNPs and definition of appropriate germplasm sampling in addition to platform section impact on logistical and resource-use considerations for breeding and conservation applications when mainstreaming QC. In order to address these issues, we evaluated the selection and use of SNPs for QC applications from large DArTSeq data sets generated from CIMMYT maize inbred lines (CMLs). Two QC genotyping strategies were developed, the first is a “rapid QC”, employing a small number of SNPs to identify potential mislabeling of seed packages or plots, the second is a “broad QC”, employing a larger number of SNP, used to identify each germplasm entry and to measure heterogeneity. The optimal marker selection strategies combined the selection of markers with high minor allele frequency, sampling of clustered SNP in proportion to marker cluster distance and selecting markers that maintain a uniform genomic distribution. The rapid and broad QC SNP panels selected using this approach were further validated using blind test assessments of related re-generation samples. The influence of sampling within each line was evaluated. Sampling 192 individuals would result in close to 100% possibility of detecting a 5% contamination in the entry, and approximately a 98% probability to detect a 2% contamination of the line. These results provide a framework for the establishment of QC genotyping. A comparison of financial and time costs for use of these approaches across different platforms is discussed providing a framework for institutions involved in maize conservation and breeding to assess the resource use effectiveness of QC genotyping. Application of these research findings, in combination with existing QC approaches, will ensure the regeneration, distribution and use in breeding of true to type inbred germplasm. These findings also provide an effective approach to optimize SNP selection for QC genotyping in other species.

CONSERVACIÓN in situ Y MEJORAMIENTO PARTICIPATIVO DE MAÍCES CRIOLLOS EN LA PENÍNSULA DE YUCATÁN

<p>The objectives of this study were to estimate the diversity of maize farmed by maize growers (“milperos”) of the Yucatan Peninsula, to review the state of maize conservation from 1948 to 2010, and to try out participative methods to best conservation and improvement of maize. Data of samples collected in 1948, 1974 and 1977 were analyzed; ethnobotanical explorations were carried out in 1999 and 2010; three cycles of visual stratified masal selection with four Creole maize were also practiced; and exhibition seeds in 44 localities were registered. The 1999 and 2010 explorations included 153 donors from 56 localities and 177 donors from 68 localities, respectively. Two-hundredth and thirty-six and 163 seed samples were collected from local populations of maize in the first and second exploration. The samples collected in 1999 and 2010 corresponded to the Tuxpeño, Dzit-Bacal, Nal-Tel landraces and crosses of them. In 1999 and 2010, it was found that 66.7% and 71.0% of the “milperos” interviewed, conserved and selected seeds from their maize populations for 6 or more years. The conservation of local maize increased 15.5%. However, the conservation of Dzit-Bacal maize decreased 14.2% in 10 years; therefore, its informal supply was strengthen in regional exhibitions of seeds and participative improvement of populations of that maize landrace was carried out, to reinforce its in-situ conservation and diversity.</p>

Control de la temperatura para la prevención de plagas poscosecha en la conservación de granos

The postharvest insect plagues are the main cause of grain quality lost during storage period, fundamentally in tropical climate zones due to the high values of temperature and humidity. The storage in Refrigerated Metallic Storehouses (rms) is one of the principal technologies for the conservation of large grain quantities during long time period. The atmospheric variables are modified by using vehicles equipped with cool air compressors which are shared among several storehouses. The inadequate usage of these cold carts causes that temperature and/or humidity in the rms run out of the specifications for the maize conservation. This research aims to analyse and forecast the temperature and humidity behavior in a rms in order to evaluate and to improve the cooling process. A forecasting model for the temperature in the rms is built using trend lines, which is employed to plan the adequate usage of the cold carts.

Effects of maize conservation techniques on the apparent total tract nutrient and mineral digestibility and microbial metabolites in the faeces of growing pigs

A digestibility trial was conducted to investigate the effects of different maize conservation techniques on the nutrient digestibility of a commercial maize–soybean meal diet fed to growing pigs. The influence on the content of biogenic amines, volatile fatty acids (VFAs) and ammonia in the faeces was also determined. Maize was either dried (dried maize), ensiled after milling (maize silage) or tight-closed-stored (TCS-maize) as a whole grain. Nine growing pigs (35.1±0.8kg) were used in a 3×3 Latin square experiment. They were fed diets based on the different maize conserves, barley and soybean meal to ensure the same content of N, energy and digestible phosphorus (P) in the diet. The apparent total tract digestibility (ATTD) of the DM, ash and starch was improved (P<0.05), and the ATTD of the ether extract tended to be improved (P<0.10) when the maize was fermented. Moreover, based on the results related to the ATTD of P in the different maize conserves of a previous study, less P was added to diets that were based on fermented maize. Nevertheless, the P excretion was reduced without compromising P utilisation. The metabolic products of the gut microorganisms, biogenic amines and most VFAs in the faeces were reduced when the animals were fed fermented maize (P<0.05). The observed effects were more pronounced in the maize silage treatment. In conclusion, the current data suggest that the air-proofed storage of wet maize can be a strategy to improve the feeding value of maize-based diets fed to pigs.

Effect of maize conservation technique and phytase supplementation on total tract apparent digestibility of phosphorus, calcium, ash, dry matter, organic matter and crude protein in growing pigs

Two experiments were carried out to investigate the effect of different maize conservation techniques and phytase addition on coefficients of total tract apparent digestibility (CTTAD) of phosphorus (P), calcium (Ca), ash, dry matter (DM), organic matter (OM) and crude protein (CP). In the first experiment, 9 growing pigs were allotted to a triplicate 3×3 Latin square design to measure CTTAD of P in three different maize conserves. Maize was either dried (dried maize), ensiled after milling (maize silage) or tight-closed-stored as whole grain (TCS-maize). Diets consisted of the differently conserved maize alone supplemented with amino acids and a mineral and vitamin source. To achieve P-deficient diets, no P was added. In experiment 2 same experimental design, diet composition and feedstuffs were used as in the first study. However, in this study diets were supplemented with 750FTUphytasekg−1 diet from Schizosaccharomyces pombe. To evaluate the effect of phytase supplementation, results of both experiments were pooled for statistical analysis. The obtained results show that the CTTAD of P was greater (P<0.0001) when maize was fermented compared with dried maize (0.42 in maize silage, 0.37 in TCS-maize, 0.28 in dried maize). The CTTAD of P was enhanced in all conservation types through phytase addition (0.46 in dried maize, 0.55 in maize silage and 0.52 in TCS-maize) (P<0.0001). Moreover, CTTAD of Ca was higher in the fermented maize groups (P<0.0001) compared with dried maize. However, it was not influenced by phytase supplementation.The CTTAD of DM and OM were not influenced by fermentation. The CTTAD of CP was lower in fermented maize (P<0.05) compared to dried maize, whereby this effect was more pronounced in maize silage. However, the CTTAD of DM, OM and CP were not influenced by phytase supplementation.In conclusion, maize fermentation in the form of ensiling increases CTTAD of P in growing pigs. Therefore lower P supplementations are required and P excretions with manure can be reduced. Although CTTAD of P is improved when phytase is added, fermentation still offers advantages compared to dried maize.

Identification of genes related to germination in aged maize seed by screening natural variability

Ageing reduces vigour and viability in maize inbred lines due to non-heritable degenerative changes. Besides non-heritable genetic changes due to chromosome aberrations and damage in the DNA sequence, heritable changes during maize conservation have been reported. Genetic variability among aged seeds of inbred lines could be used for association studies with seed germination. The objective of this study was to identify genes related to germination in aged seeds. The sweet corn inbred line P39 and the field corn inbred line EP44 were used as plant material. Bulks of living and dead seeds after 20 and 22 years of storage were compared by using simple sequence repeats (SSRs) and, when the bulks differed for a marker, the individual grains were genotyped. Differences between dead and living seeds could be explained by residual variability, spontaneous mutation, or ageing. Variability was larger for chromosome 7 than for other chromosomes, and for distal than for proximal markers, suggesting some relationships between position in the genome and viability in aged seed. Polymorphic SSRs between living and dead seeds were found in six known genes, including pathogenesis-related protein 2, superoxide dismutase 4, catalase 3, opaque endosperm 2, and metallothionein1 that were related to germination, along with golden plant 2. In addition, five novel candidate genes have been identified; three of them could be involved in resistance to diseases, one in detoxification of electrophillic compounds, and another in transcription regulation. Therefore, genetic variability among aged seeds of inbreds was useful for preliminary association analysis to identify candidate genes.

Maize population hybrids: Successful genetic resources for breeding programs and potential alternatives to single-cross hybrids

Conservation of maize ( Zea mays L.) genetic resources has been the emphasis of national and international institutions for the benefit of mankind. However, limited resources have been devoted to their adequate exploitation, making genetic resources less useful to the public and private scientific community. As a consequence, public maize breeders have exploited a limited number of heterotic combinations for cultivar development and basic molecular studies while genetic effects are different for different hybrids. Extensive testing of maize population hybrids is a successful approach to choose and improve germplasm sources with high mean performance, useful genetic variability, and excellent combining ability. There is a need to keep applied breeding programs strong in order to link efforts in germplasm conservation with its improvement and utilization.

Conservation in a changing world: in situ conservation of the giant maize of Jala

Using survey data from Jala, Mexico, this case-study evaluates in situ maize conservation of the variety ‘Jala’ (Zea mays L.). Though historically ‘Jala’ was the dominant variety grown in the valley of Jala, today less than 20% of farmers grow it on only 5% of the maize area. Younger growers of the ‘Jala’ variety specialize in it, growing relatively large amounts for niche markets. Older, diversified farmers grow small areas for household use and to compete in a local contest. Conservation of the ‘Jala’ variety has been heavily influenced by shifting ideal concepts of maize, as determined by market and consumption demands and by a contest designed to promote in situ conservation. The current move away from nationalized purchasing may favor ‘Jala’s’ continued conservation.

Einfluss der Häcksellänge auf Verdichtbarkeit, Silierung und Nacherwärmung von Silomais

Quality losses in maize conservation due to secondary fermentation still cause considerable practical problems in dairy cattle feeding. Presumably this problem will become even more severe in the future. Therefore, the goal of this study was to determine t