Maize Research Research Articles

CONTRIBUTION OF ORGANICALLY GROWN SPELT TO THE GRAIN QUALITY

The content of nutritionally important minerals (Fe, Mg, Zn, Ca, Mn) and some antioxidants were analyzed in spelt wheat grown during four different seasons and in semiarid conditions. The spelt wheat was organically grown in the period 2012-2015, at Maize Research Institute Zemun Polje. The crop was sown on the area of 0.33 ha and after harvesting, grain yield was measured from all production area and calculated with 14% of moisture. Then, grains were milled and content of nutrients Mg, Fe, Mn, Ca and Zn, as well as inorganic phosphorus (Pi), phytic phosphorus (Pphy), phenolics, β-carotene and glutathione (GSH), were determined in grains. The variations in content of minerals and antioxidants followed variations in sum of precipitation, as well as average air temperature. The content of Mg was significantly higher in 2015, while the Ca content was lower. Concentration of Zn and Mn continuously decreased from 2012 to 2015. The highest content of almost all investigated antioxidants was observed mostly in 2013. GSH and β-carotene content variations were also affected by the meteorological conditions of the growing season.

THE EFFECT OF COVER CROPS ON THE CONTENT OF PROTEIN IN GRAIN OF SWEET MAIZE

The study was conducted in the experimental field of the Maize Research Institute Zemun Polje, Serbia, during 2013/14-2014/15. The experiment was established as a block design with four replications. As winter cover crops-CC (factor A) the following plants were grown: CV–common vetch (Vicia sativa L.), FP-field pea (Pisum sativum L.), WO-winter oats, (Avena sativa L.), FK-fodder kale (Brassica oleracea (L.) convar. acephala), two mixture variants of legume crops with oats (CV+WO and FP+WO) and two control treatments: a variant in which the surface was covered with dead organic mulch (DOM) and traditional variant: after ploughing in the fall plot stayed uncovered during the winter (TV). Green biomass of the cover crops was incorporated in the soil, immediately after, half of the elementary plot was infested with bio-fertilizer (BF) - Uniker (mobilizer of nutrients) in an amount of 10 l ha-1 (factor B), which contains the strains of cellulolytic and proteolytic bacteria to support the mineralization of entered crop residues. The seeds of sweet maize ‘ZPSC 421su (FAO 400) were sown at the arrangement of 70 cm between rows and 22 cm between plants in the row (65,000 plants per ha). Preceding crop in both years was winter wheat. The kernel protein content was measured on infrared analyser. The data were processed by ANOVA. The investigated factors (CC and BF) showed significant effect on protein content in sweet maize kernel in both years. As it was expected, the greatest impact on protein content was exhibited in leguminous species grown alone, or in mixtures with oats, particularly in the dry, 2015. Small grains intercropped with legumes obtained higher values of protein content than small grain grown as monocrops.

Grain Quality Within ex situ and in situ Conserved Traditional White Maize Landraces

White maize had an important role in human nutrition throughout the Western Balkan region. A great number of farmers (approximately 86% in Serbia) still grow traditional white Open Pollinated Varieties (OPVs) for human diet. Out of 2217 maize landraces stored within Maize Research Institute „Zemun Polje” (MRIZP) gene bank, more than 700 are white kernel accessions. Eighteen white maize landraces, collected in the Western Balkan region in different periods, were selected for the present study. By the evaluation of agromorphological performances and the basic chemical composition of grain, the objective was to determine the importance of landraces conserved under in situ and ex situ conditions, to be used as the initial material for breeding. The idea was to determine whether the varieties conserved under ex situ conditions (collected from the same or different regions) distinguish from varieties permanently grown in the region of western Serbia. It was found that varieties permanently grown in the western Serbia were more similar to varieties of the ex situ collection from eastern Bosnia and Herzegovina than to varieties collected in western Serbia 50 years ago. The comparison between OPVs and modern white maize hybrids for the basic chemical composition of grain showed the significant potential of OPVs for nutritive grain quality improvement. Increased organic production creates new possibilities for more intensive incorporation of OPVs into this agricultural system. New opportunities for the cooperation and share of responsibilities among breeders, farmers and genetic resources managers are initiated, to be used for in situ maize genetic resources conservation improvement. More detailed characterisation and evaluation of the white maize landraces will offer an explanation of what has motivated our farmers to maintain the OPVs production through centuries, despite the availability of modern hybrids.

Populacioni nivo imaga kukuruzne zlatice u periodu od 2005-2009 godine

Western corn rootworm (WCR) (Diabrotica virgifera virgifera LeConte) is one of the most important and potentially most dangerous pests of maize. Since its occurrence in Serbia in 1992, it has been present in almost all areas under maize cultivation. Alongside with all preventive measures, first of all, the crop rotation, which is considered the most economic one, a great attention has been paid to the forecast of the pest occurrence based on the flight dynamics and the population level. The flight dynamics, sex dominance, variations in the population level depending on the trap types and climate factors were observed on two locations: Crepaja in three-year continuous cropping (2005-2007) and in the experimental field of the Maize Research Institute, Zemun Polje in the duration of five years (2005-2009). According to the flight dynamics of WCR adults, the highest population level of this pest was observed in 2005, while the comparison of the number of adults over locations showed greater abundance of the pest in Crepaja than in Zemun Polje, which was attributed to extreme favourability of agro-ecological conditions on this location for the WCR development. The 2008-2009 period was characterised by the reduced number of WCR, which coincided with the extremely arid conditions that do not favour the development of this pest.

Construction of the third-generation Zea mays haplotype map.

BackgroundCharacterization of genetic variations in maize has been challenging, mainly due to deterioration of collinearity between individual genomes in the species. An international consortium of maize research groups combined resources to develop the maize haplotype version 3 (HapMap 3), built from whole-genome sequencing data from 1218 maize lines, covering predomestication and domesticated Zea mays varieties across the world.ResultsA new computational pipeline was set up to process more than 12 trillion bp of sequencing data, and a set of population genetics filters was applied to identify more than 83 million variant sites.ConclusionsWe identified polymorphisms in regions where collinearity is largely preserved in the maize species. However, the fact that the B73 genome used as the reference only represents a fraction of all haplotypes is still an important limiting factor.

Evaluation of Grain Yield of Heat Stress Resilient Maize Hybrids in Nepal

Midhills, foot hills and river basin areas of are generally under spring maize cultivation. These areas along with the areas from Terai and Inner Terai where spring and early summer maize are grown are the most affected from heat stress. Identification and selection of suitable varieties and traits for high temperature tolerance is vital to produce heat resilient genotypes.With a view to identify high yielding heat stress resilient maize hybrids, genotypes received from International Maize and Wheat Improvement Centre (CIMMYT) were evaluated in alpha lattice design with two to three replications at Rampur, Nepalgunj and Surkhet in 2013/014, 2014/015 and 2015/016. Total 57 trials consisting of 7764 maize hyrbids were evaluated under heat stress conditions. At Nepalgunj and Surkhet, trials were planted in March/April. Out of the tested genotypes, 24 hybrids were found promising based on grain yield, plant and ear height. These 24 hybrids along with four National Maize Research Program (NMRP) developed and two multi-national companies’ hybrids as checks were tested in multilocation trials at Dumarwana, Nijgadh, Nawalparasi and Rampur in 2014/015. Out of these 24 hybrids, eight were selected and tested during 2015/016 in Dumarwana, Nijgadh, Nawalparasi, Anandapur and Rampur. Based on results combined over years and locations CAH-151 (8629 kg ha-1) and CAH-153 (8955 kg ha-1) were registered for general cultivation as Rampur Hybrid-8 and Rampur Hybrid-10, respectively. Other promising hybrids were CAH-1511 (8800 kg ha-1) followed by CAH-1515 (8678 kg ha-1), RML-95/RML-96 (8486 kg ha-1), CAH-1513 (8258 kg ha-1) and RML-86/RML-96 (7544 kg ha-1), respectively. Stability analysis revealed that CAH-151, CAH-153, CAH-1515, CAH-1511 and RML-95/RML-96 are stable hybrids having good performance.

Evaluation of Maize Genotypes against Southern Leaf Blight (Bipolaris Maydis) During Summer Seasons at Rampur, Chitwan

Maize genotypes were screened at research field of National Maize Research Program, Rampur, Chitwan on 20 maize genotypes during 2015 and 2016 summer season with the objective of identification of resistant genotypes against southern leaf blight caused by Bipolaris maydis. Field experiment was laid out in randomized complete block design with three replications. Disease scoring was done as percentage of leaf area infected using 1-5 rating scale. In both the years among the tested genotypes, disease severity and grain yield varies significantly. None of the genotypes reacted for resistant whereas four genotypes; 05SADVI, BGBYPOP, RAMS03F08 and RML-32/RML-17 were moderately resistant over the years. For grain yield most of the tested genotypes produced comparatively lower grain yield however RML-32/RML-17 was superior for grain yield (3.1 t/ha) over the years. Int. J. Appl. Sci. Biotechnol. Vol 5(4): 532-536

Response of Maize to the Soil Application of Nitrogen and Phosphorous Fertilizers

Poor nutrient management is one of the key factors contributing to decline in the productivity of maize in Nepal. Few studies have been done on developing site and variety specific fertilizer recommendation. Therefore, a field experiment was conducted at National Maize Research Program (NMRP) Rampur, Chitwan during winter season in September 2016 to study the response of hybrid maize (RML95/RML96) to different doses of soil application of nitrogen (N) and phosphorous (P). The treatments included were 120:60, 120 :( 40+20), 160:60, 160 :( 40+20), 200:60, 200 :( 40+20), 240:60, and 240 :( 40+20) N: P kg ha-1. Potassium fertilizer was fixed and applied as per the Government recommendation i.e., 40 kg K ha-1.Eight treatments were replicated three times in randomized complete block design and maize was planted in six rows of four meter long plot. The research findings revealed that each level of N significantly increased grain yield up to 240 kg N ha-1. The grain yield (8.8 t ha-1) obtained under 240 kg N ha-1 was significantly higher than that obtained under 120,160 and 200 kg N ha-1. However, the results revealed that split application of P failed to bring about any significant difference in the grain yield as well as yield parameters of maize. We can, thus conclude that the addition of increasing rate of N increases the yield and yield attributing characters of maize. Int. J. Appl. Sci. Biotechnol. Vol 5(4): 537-541

Growth rate rather than growth duration drives growth heterosis in maize B104 hybrids.

Research in maize is often performed using inbred lines that can be readily transformed, such as B104. However, because the B104 line flowers late, the kernels do not always mature before the end of the growing season, hampering routine seed yield evaluations of biotech traits introduced in B104 at many geographical locations. Therefore, we generated five hybrids by crossing B104 with the early‐flowering inbred lines CML91, F7, H99, Mo17, and W153R and showed in three consecutive years that the hybrid lines proved to be suitable to evaluate seed yield under field conditions in a temperate climate. By assessing the two main processes driving maize leaf growth, being rate of growth (leaf elongation rate or LER) and the duration of growth (leaf elongation duration or LED) in this panel of hybrids, we showed that leaf growth heterosis was mainly the result of increased LER and not or to a lesser extent of LED. Ectopic expression of the transgenes GA20‐oxidase (GA20‐OX) and PLASTOCHRON1 (PLA1), known to stimulate the LER and LED, respectively, in the hybrids showed that leaf length heterosis can be stimulated by increased LER, but not by LED, indicating that LER rather than LED is the target for enhancing leaf growth heterosis.

Biochemical and physical kernel properties of a standard maize hybrid in different TopCross™ Blends

A pilot experiment was undertaken in order to examine high oil populations of maize (Zea mays L.) to be used as pollinators in TopCross blends with commercial ZP341 standard hybrid. Five high oil populations (HOPs) from the Maize Research Institute (MRI) gene bank were chosen for this research, according to their high grain oil content, synchrony between silking of ZP341 and anthesis of the populations and good agronomic performances in 2012. Selfing of ZP341 and HOPs, as well as crosses of ZP341 cmsS sterile × HOPs were carried out in 2013. Oil content, fatty acid composition, protein and tryptophan content, and physical characteristics of the obtained kernels were measured. Four HOPs showed significant positive influence on the oil content in the TopCrosses (TC), 16.85 g kg−1 on average. Oleic acid, which is the principal monounsaturated fatty acid, was significantly lower in all HOPs and all TCs, while selfed ZP341 had almost twice the average value typical for standard maize. However, this decrease in TCs was in a narrow range from 1 % (in TC-3) to 5 % (in TC-4) and the oleic content of TCs was on average higher by 60 % compared to the typical standard maize. Different favorable and unfavorable significant changes were detected in fatty acid compositions, protein and tryptophan contents and physical kernel properties for each potential TC combination. Results indicate differences in gene effects present in different TC combinations and underscore the need to examine each potential TC blend by conducting similar simple experiments.

A splice site mutation in shrunken1-m causes the shrunken 1 mutant phenotype in maize

Endosperm development plays an important role in the determination of grain weight in maize. In this context, a spontaneous recessive shrunken kernel mutant, shrunken1-m (sh1-m), identified from improved maize inbred line Zheng58 (Gai-Z58) was studied. Physiological and microscopic analysis revealed that the sh1-m mutant significantly increased the content of amylose, and its starch granules showed distinctive morphology. Utilizing 1877 recessive sh1-m individuals from a BC1 segregating population of B73/sh1-m and 19 molecular markers, the sh1-m gene was limited to a 2.1 kb interval within the GRMZM2G089713 gene. A 5-bp substitution in sh1-m covering the 3′ end of the thirteenth exon and the 5′ splicing site of the thirteenth intron led to a missense mutation and a mis-splicing site that resulted in early translational termination. sh1 reference mutant sh1-912A (shrunken-912A) had a single transversion at the 3′ splice junction of the second intron resulting in a mis-splicing site causing the 13-bp spliced out in the third exon and the initiation codon to shift to 118-bp downstream. Further genetic allelism tests between them confirmed that sh1-m is a novel allele of the Sh1 locus. Sh1 was constitutively expressed in all tested tissues, and its expression pattern/level was not significantly changed in developing seeds of the sh1-m mutant. Transcript mRNA patterns/levels of some other genes involved in starch biosynthesis was significantly altered in the sh1-m mutant. These results provide direct evidence that sh1-m plays a key role in starch biosynthesis and provide valuable information for grain quality research and breeding in maize.

Construction and Optimization of a Large Gene Coexpression Network in Maize Using RNA-Seq Data.

With the emergence of massively parallel sequencing, genomewide expression data production has reached an unprecedented level. This abundance of data has greatly facilitated maize research, but may not be amenable to traditional analysis techniques that were optimized for other data types. Using publicly available data, a gene coexpression network (GCN) can be constructed and used for gene function prediction, candidate gene selection, and improving understanding of regulatory pathways. Several GCN studies have been done in maize (Zea mays), mostly using microarray datasets. To build an optimal GCN from plant materials RNA-Seq data, parameters for expression data normalization and network inference were evaluated. A comprehensive evaluation of these two parameters and a ranked aggregation strategy on network performance, using libraries from 1266 maize samples, were conducted. Three normalization methods and 10 inference methods, including six correlation and four mutual information methods, were tested. The three normalization methods had very similar performance. For network inference, correlation methods performed better than mutual information methods at some genes. Increasing sample size also had a positive effect on GCN. Aggregating single networks together resulted in improved performance compared to single networks.

Evaluation of saline tolerance at the seedling stage of various maize cross combinations

This study was conducted at the Maize Research Instituteof Vietnam using 24 maize hybrids, identified as STM1 to STM24, at five different salt concentrations, which were 0, 50, 100, 150, and 200 mM NaCl. After seven days of germination at room temperature, seedlings were transplanted to nutrient-rich solutions salinized with salt. 17 day-old seedlings were then harvested to calculate their growth parameters of the day to seedlings fully wilt and degradation, root and shoot length, seedling dry matter production, and content. As the study results show, salt stress caused the reduction of plant growth in all hybrids, however, the STM10 and STM21 varieties showed the best salt tolerance, while STM17 and STM18 presented most salt-sensitive. The analyzed results for Na+ and K+ showed that among the hybrids, STM21 had lower Na+ and higher K+ contents in both roots and shoots of the seedlings than others.

Productivity Change Trend Analysis of Thai Maize Production: An Application of Malmquist Productivity Index Approach

<div><p><em>The purpose of this study is to measure and analyze the productivity change of Thai maize production by using Malmquist productivity index </em>(<em>MPI</em>)<em> approach from the year </em><em>2008to 2015</em><em>. </em><em>The results analysis found that the maize productivity change in Thailand over study period</em><em>s</em><em> had the average productivity progression at 1.6% and its cause was the technical efficiency change and the technological </em><em>change</em><em>. </em><em>However, some provinces still need to be improved the change of productivity. </em><em>Furthermore, our findings indicated that the North had a productivity progression about 4.6%. Meanwhile, the Northeast and Central revealed a productivity regression at 0.4 and 1.1%, respectively. </em><em>Based on the empirical finding, this study could provide important information for proposing policy implications which will be useful to the </em><em>government, farmers, maize research institutes, and development partners for enhancing the sustainable maize productivity trend in some provinces of Thailand.</em><em></em></p></div>

A simple and efficient non-denaturing FISH method for maize chromosome differentiation using single-strand oligonucleotide probes.

Single-strand oligonucleotides (SSONs hereafter) as probes are becoming a powerful method of chromosome painting in many species. In this study, nine SSONs ((ACT)10, (ACT)19, Knob-1, Knob-2, Knob-3, CentC69-1, MR68-3, K10-72-1, and TR1-357-2) were developed and used for chromosome identification in 16 maize (Zea mays L., 2n = 20) inbred lines and hybrids by non-denaturing fluorescence in situ hybridization (ND-FISH). Each SSON produced clear signals on 2-10 chromosomes of inbred lines B73 and Mo17. A multiplex probe set containing four SSONs ((ACT)10, Knob-2, CentC69-1, and MR68-3) clearly characterized all maize chromosomes in the 16 lines by a single round of ND-FISH and revealed genetic variation at a chromosome level. For example, unique signals on chromosome 6 clearly distinguished all 16 genotypes. The SSONs and multiplex probe developed in this research will facilitate genotype identification and chromosome research in maize.

Grey leaf spot disease of maize and food security research

Grey leaf spot disease of maize and food security research

Surveying the Maize community for their diversity and pedigree visualization needs to prioritize tool development and curation.

The Maize Genetics and Genomics Database (MaizeGDB) team prepared a survey to identify breeders’ needs for visualizing pedigrees, diversity data and haplotypes in order to prioritize tool development and curation efforts at MaizeGDB. The survey was distributed to the maize research community on behalf of the Maize Genetics Executive Committee in Summer 2015. The survey garnered 48 responses from maize researchers, of which more than half were self-identified as breeders. The survey showed that the maize researchers considered their top priorities for visualization as: (i) displaying single nucleotide polymorphisms in a given region for a given list of lines, (ii) showing haplotypes for a given list of lines and (iii) presenting pedigree relationships visually. The survey also asked which populations would be most useful to display. The following two populations were on top of the list: (i) 3000 publicly available maize inbred lines used in Romay et al. (Comprehensive genotyping of the USA national maize inbred seed bank. Genome Biol, 2013;14:R55) and (ii) maize lines with expired Plant Variety Protection Act (ex-PVP) certificates. Driven by this strong stakeholder input, MaizeGDB staff are currently working in four areas to improve its interface and web-based tools: (i) presenting immediate progenies of currently available stocks at the MaizeGDB Stock pages, (ii) displaying the most recent ex-PVP lines described in the Germplasm Resources Information Network (GRIN) on the MaizeGDB Stock pages, (iii) developing network views of pedigree relationships and (iv) visualizing genotypes from SNP-based diversity datasets. These survey results can help other biological databases to direct their efforts according to user preferences as they serve similar types of data sets for their communities. Database URL: https://www.maizegdb.org

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.

Comparison of two cold test procedures for seed vigour evaluation of maize inbred lines

Cold test (CT) is a valuable method of assessing maize seed vigour. Although widely used CT is not standardized because of variations in CT procedures. The objective of this study was to evaluate seed vigour of 15 maize inbred lines developed at the Maize Research Institute Zemun Polje, using two different substrates (soil and sand) in a severe CT (7.5°C for 10 days followed by 7 days at 20/30 °C). Statistical analysis showed that inbred lines differ significantly in seed vigour, and no difference between two applied substrates in CT. Coefficients of variation were lower in CT with sand (6.05 %), compared to the CT with soil (6.74%) due to variation in soil quality and presence of soil-borne pathogens. Both CT procedures were highly correlated with field emergence. Results of this research indicate that CT with sand is appropriate for testing maize seed vigour, with the potential for standardization.

Disruption of genetic identity for genebank maize accessions during conservation

Maintenance of the original accessions identity and integrity is one of the priorities among genebank activities. Different factors related to conservation may result in accessions disruption. Regeneration is the most frequent critical point in this process, due to bottlenecks, inbreeding, random genetic drift and unintentional mixing or contamination. On the other hand, genetic drift may occur due to seed viability loss. Therefore, it is very important to establish the balance between the frequency of regeneration and the duration of accession conservation. The aim of the present study was to estimate whether the identity of accessions regenerated after 27 years of medium-term conservation was disrupted. Phenotypic markers were applied on three Maize Research Institute ?Zemun Polje? (MRIZP) genebank maize landraces (K2026, K768 and K86), differing in seed viability, kernel type and effective population size. It was estimated that, after the regeneration, there had been no significant changes in the landrace K2026. There were some parameters indicating that genetic drift had occurred in the landrace K768, and that there had been even a certain degree of inbreeding in the landrace K86. According to the results, accession K2026 could still be kept under the same ID number. Due to the genuine identity disruption, assignment of new ID numbers for K768 and K86 should be suggested.