Quality Of Maize Grains Research Articles

The influence of storage conditions on starch and amylose content of South African quality protein maize and normal maize hybrids

The quality of maize grains during storage is affected by unfavourable storage conditions, resulting in physicochemical changes in specifically amylose and starch content that lead to significant product qualitative and quantitative losses. The objective of this study was to evaluate the starch and amylose content of normal maize and quality protein maize (QPM) seed samples at different temperature treatments: in cold storage at 3.6 °C, at room temperature (18.5 °C) and at 30 °C for 0, 6 and 12 month storage periods, respectively. Sixteen genotypes were tested in a single trial at Potchefstroom in South Africa. Due to optimal growing conditions the seed was of excellent quality. Storage at 3.6 °C and 18.5 °C caused some reduction in amylose and starch content, although for starch it was not significant. On the other hand, storage at 30 °C significantly (P ≤ 0.05) reduced the starch and amylose content after both 6 and 12 month periods of storage. QPM and non-QPM seed reacted similarly to storage conditions, and there were larger differences between cultivars than between QPM and non-QPM material. Even at relatively high relative humidity, low temperature storage maintained seed quality the best. Therefore high temperature storage is detrimental to starch and amylose content of both normal maize and QPM, especially after 6 months or more of storage. Maize should therefore be stored under low temperatures (around 4 °C) or if not possible, at least under 19 °C.

Physiological Effects of Salicylic Acid and Thiourea on Growth and Productivity of Maize Plants in Sandy Soil

This study aimed to investigate the response of vegetative growth, yield, and some metabolic constituents of maize grains cv. Single Cross 124 to foliar applications of salicylic acid (SA; 100, 200, and 400 mg L−1) and thiourea (TU; 500, 1000, and 1500 mgL−1), two bioregulators, either alone or in combination. The foliar application of SA and TU alone significantly increased stem diameter, number of leaves / plant, leaf area, total dry weight / plant, leaf area index, net assimilation rate, specific leaf weight, and yield (i.e., ear length, ear diameter, number of grains / row, number of rows / ear, 100-grain weight, grain yield / plant, grain yield / fed (1 feddan = 4200 m2), harvest index, and shelling percentage) by increasing SA or TU concentrations up to 200 and 1500 mg L−1, respectively. Salicylic acid and TU, when applied alone, significantly improved the nutritional value and quality of maize grains by increasing crude protein, total soluble sugars, total free amino acids, and total soluble phenols.

Yield and quality of maize following the foliar application of a fertilizer based on the byproduct “shale water”

The water extracted from the shale rock (shale water) through the pyrolysis process to obtain fuel oil and other products shows a composition based on organic compounds and a wide range of minerals and trace elements with an important role in plant nutrition, suggesting its use as a fertilizer. Thus, the influence of foliar application of shale water (SW), with or without the micronutrients zinc (Zn), manganese (Mn), copper (Cu), boro (B) and molybdenum (Mo), was evaluated regarding yield and quality of maize grains. The yield, the total antioxidant activity, and the content of starch, phenolic compounds and carotenoids were improved in maize grains following the application of three doses of 7 L/ha of SW, which indicates that SW may influence the primary and secondary metabolisms. The application of SW with micronutrients resulted in the increase of grain yield; however, did not result in the improvement of grain quality. The foliar fertilizer formulations also had an influence in the content of minerals and aminoacids of the grain. The results indicate that SW has potential to be used in agriculture to improve yield and quality of maize.

Grain yield and quality of maize hybrids in different FAO maturity groups

An improvement in the quality of maize grain by increasing the level of components responsible for its biological value is possibleby using genetic means. However, a change in the genotype, together with improving the nutrient properties of the grain, also has someadverse consequences connected with a fall in yield and in resistance to diseases.Field experiments were conducted during three years (2003, 2004and 2005) to evaluate environmental effects on grain yield andquality responses of maize hybrids. Twenty one hybrids of various maturity groups (FAO 150-400) were planted to achieve an optimum(60-70 000 plants per hectare) plant populations and grown under the medium-N (80 kg N ha-1) fertilization. Environmental conditionssignificantly affected maize hybrid responses for grain yield, starch, oil and protein contents, and consequently, starch, oil and proteinyields per hectare. Hybrids of flint type, which have a short vegetation period, had high protein and oil content but the yield averageswere low due to the slower rate of starch incorporation. Hybrids of the dent type have a longer growing season and more intensecarbohydrate accumulation, but low protein and oil contents. In wet years there was a higher rate of starch accumulation, while dryyears are favorable for protein and oil accumulation. Positive correlation existed between starch content and grain yield and 1000-weight as well as between oil content and volumetric weight among tested hybrids. Negatively correlation existed between grain oil andstarch content as well as between oil content and grain yield and 1000-weight. Thus, end-users that require high quality maize may needto provide incentives to growers to off set the negative correlation of grain yield with oil and protein content.

Quality of maize grains treated with allyl isothiocyanate stored in hermetic bags

This purpose of this study was to evaluate the quality of maize grain treated with allyl isothiocyanate (AITC) and stored under hermetic conditions. Maize grains with moisture contents of 14.8 or 17.9% wet basis (w.b.) initial moisture content were packaged in high density polyethylene bags and submitted to treatment with AITC at a concentration of 300 μL kg −1. The bags were stored in controlled temperature chambers at 15, 25 or 35 °C. At 30-day intervals, for a period of 150 days, three bags were removed from the chambers and the grains were submitted to commercial classification, moisture content, bulk density, germination potential and electrical conductivity analyses. It was verified that AITC at 300 μL kg −1 has no significant effect on the physiological quality of maize grains stored in hermetic bags. The microbiological analyses indicate the control of fungi and yeasts on the grains stored with 17.9% w.b. and treated with AITC. The maize grains stored with 14.8% w.b. moisture content in hermetic systems suffered no deterioration and retained their quality for a longer period than grains stored with 17.9% w.b. moisture content, independent of AITC treatment.

Impact of bacterial biological control agents on fumonisin B 1 content and Fusarium verticillioides infection of field-grown maize

The effects of four bacterial biocontrol agents on Fusarium verticillioides infection and fumonisin accumulation in the maize agroecosystem were evaluated in a 2-year field study. The antagonistic abilities of the four agents were examined following two application techniques consisting of inoculating seeds during pre-sowing and maize ears at flowering. Seed inoculation with F. verticillioides and co-inoculation with this fungus and each of the four agents were also examined. Treatment effects on maize performance were also assessed through determination of the number of plants per hectare, kernels yield (kg ha −1) and kernel–cob relations. F. verticillioides infection and fumonisin B 1 contents were determined in kernels of physiologically mature maize plants at harvest time. Maize yield remained unchanged with respect to controls in both field surveys; however significantly higher FB 1 contents were obtained after inoculation of seeds with F. verticillioides M7075. Seed treatment with Bacillus amyloliquefaciens and Enterobacter hormaechei reduced the infection by the fungus and FB 1 contents both years of the study while ear inoculation produced highly variable results. The number of colony forming units of F. verticillioides obtained from harvested maize kernels was positively correlated with fumonisin B 1 content; however none of these parameters showed significant correlation with kernel yield. The overall results suggest that in years conducive for F. verticillioides infection and fumonisin production, seed treatment with Bacillus amyloliquefaciens and Enterobacter hormaechei may improve quality of maize grains obtained at harvest by reducing toxin content.

Aplicação de ozônio contra Sitophilus zeamais e Tribolium castaneum em milho armazenado

Neste trabalho a meta principal foi avaliar a suscetibilidade dos adultos de Sitophilus zeamais (Motschulsky) (Coleoptera: Curculionidae) e Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) e a qualidade fisiológica dos grãos de milho submetidos ao tratamento com ozônio, em diferentes camadas da massa de grãos, razão pela qual se construíram gaiolas de 3,0 cm de altura e 15,0 cm de diâmetro, em PVC, sendo o fundo e a tampa confeccionados em tecido do tipo organza; as gaiolas foram dispostas em recipientes cilíndricos, também em PVC, com 20 cm de diâmetro, 100 cm de altura e conexões para injeção e exaustão do gás ozônio. Tanto os insetos quanto os grãos de milho foram submetidos a uma atmosfera modificada com 50 mg kg-1 de ozônio injetado a um fluxo contínuo de 8,0 L min-1 em conexão localizada na base (plenum) do recipiente, em diferentes períodos de exposição. A espécie que se mostrou mais susceptível foi a S. zeamais, independentemente da sua distribuição na massa de grãos. O menor período de exposição para controlar 95% dos adultos de S. zeamais e T. castaneum foi de 23,76 e 64,19 h, respectivamente, quando distribuídos próximos à injeção do gás ozônio; em geral, os tratamentos com atmosfera modificada com 50 mg kg-1 de ozônio não afetaram a qualidade fisiológica dos grãos de milho.

The effect of moisture level on high-moisture maize ( Zea mays L.) under hermetic storage conditions— in vitro studies

Under humid and warm conditions harvested grains are susceptible to molding and rapid deterioration. Therefore, they should be dried to safe moisture levels that inhibit the activity of microorganisms. Drying to these moisture levels is not economical for farmers in developing countries. Preservation of grains at intermediate moisture levels under hermetic storage conditions could be feasible and economical in warm and moist climates. The purpose of the current study was to examine the effect of various moisture contents (m.c.) on the quality of maize grains in self-regulated modified atmospheres during hermetic storage. Maize at 14, 16, 18, 20 and 22% m.c. was initially conditioned for 28 days in tightly wrapped plastic bags and then stored in sealed containers at 30 °C for up to 75 days. Carbon dioxide produced within the containers replaced the oxygen. As the m.c. increased the time for O 2 depletion shortened, from 600 h at 14% m.c. to 12 h at 22%. The maize at 20 and 22% m.c. exhibited the highest dry matter (DM) losses, the lowest germination rates and the highest yeast and bacteria counts. The major fermentation product in the hermetically sealed maize was ethanol (0–5 g kg −1 DM), along with lower concentrations of acetic acid (0–1 g kg −1 DM). The results obtained from the in vitro experiments indicate that maize at the tested moisture levels can be stored satisfactorily under sealed conditions in which self-regulated atmospheres provide protection against microflora damage. Further large-scale trials will be needed to evaluate the economic feasibility of storing high-moisture maize.

EFFECT OF WATER ON PROTEIN, PROTEIN COMPOSITION AND RELATED ENZYME ACTIVITY IN DIFFERENT TYPES OF MAIZE

Aims The biosynthesis of maize protein, which is positively correlated to maize grain quality, is controlled by nitrate reductase (NRase), glutamine synthetase (GS), and glutamate dehydrogenase (GDH), which are affected by genetics and environment. Therefore, cultivation methods and environment affect grain quality in maize; however, there are few reports of the effects of soil water on maize grain quality and corresponding enzyme activities. Methods The experiment was carried out in pool culture within a rain-proof shelter using normal maize (Yedan 22) and high oil maize (Gaoyou 115). There were three water treatments: no irrigation after anthesis, irrigation once after anthesis (at grain filling period) and irrigation three times after anthesis (at grain filling period, milky period and wax period). Important findings Grain protein was higher in Gaoyou115 than Yedan22, and its component contents increased with increasing water supply. With different water supply, the activities of NRase, GS in leaves and GS, GDH in grains exhibited the same trends in the two types of maize. The activity of NRase decreased, and the activities of GS and GDH had unimodal curves, peaking 20 to 40 days after pollination. The activities of these enzymes increased with increased water supply. However, the activity of NRase in leaves of Yedan22 was higher than in Gaoyou115, while the activities of GS in leaves and GDH in grains were reversed, resulting in lower protein content in grains of Yedan22 than in Gaoyou115. The NRase and GS activities in maize leaves did not match grain protein content. Soil water condition was closely related with the activities of GS and GDH in ear leaves and grains of different types of maize.

Increasing Kernel Density for Two Inbred Lines of Maize

Improving grain quality of maize (Zea mays L.), including endosperm hardness and density, is often a breeding objective. Dense seed is preferred by dry millers and for alkaline processing, and can command a price premium at market. This study attempted to increase kernel density in a backcrossing program for two inbreds of maize using two selection techniques, specific gravity of kernels and the percentage of sinking kernels in a salt solution (or sinkers). Two inbreds, B73G and A632, were crossed with synthetics exhibiting apparent high kernel density, and several generations of backcrossing and self‐pollination followed. Examples of mean comparisons of backcross‐derived inbreds with the recurrent parents, B73G and A632 are as follows: B73G–Specific gravity, 1.251 and 1.206; Sinkers, 62.3 and 14.9%; and A632–Specific gravity, 1.266 and 1.250; Sinkers 45.4 and 29.1%. Both the specific gravity and sinkers techniques were successful for increasing kernel density during backcrossing.

QTL analysis of proteome and transcriptome variations for dissecting the genetic architecture of complex traits in maize.

In this review, we present some studies on genetic analysis of proteome and transcriptome variations, which exemplify new strategies for a better understanding of the molecular and genetic bases of complex traits. A large genetic variability was revealed at the proteome expression level, which raised the possibility to predict phenotypical performance on the basis of gene product variability. This approach yielded limited results, but could be re-newed by extensive identification of proteins now allowed by mass spectrometry. The dissection of the genetic basis of the variation of individual protein amounts proves very powerful to select 'candidate' proteins, physiologically relevant for a given phenotypical trait, as shown by a study on the effect of water stress in maize. In order to investigate factors of grain quality in maize, we selected a regulatory locus known to control the expression of several storage protein genes, Opaque-2, and investigated the relationships between variability in zein amount and composition and the molecular polymorphism at this locus. Moreover, a QTL analysis revealed that the variability in Opaque-2 transcript abundance was controlled by several polymorphic trans-acting regulators unlinked to the Opaque-2 structural gene. Such genetic approaches should represent additional tools for physiological analysis of the huge amounts of data generated by transcritome and proteome projects.

EFFECT OF CONTINUOUS MANURING AND FERTILISATION ON MAIZE GRAIN QUALITY AND NUTRIENT SOIL ENZYME RELATIONSHIP

An investigation to study the biochemical changes in maize under continuous application of manures and fertilisers was undertaken in Typic Ustropept soil at Tamil Nadu Agricultural University. Coimbatore. The continuous application of NPK + FYM improved the quality of maize grain by enhancing the sugar, starch and crude protein contents. The phenol content also increased. No manuring and non-inclusion of potassium and sulphur free fertiliser schedule resulted in decreased sugar, starch, crude protein and phenol contents. Appreciable variation was observed with different levels of NPK in the quality parameters of maize grain. The soil enzymes viz., amylase, catalase, cellulase. dehydrogenase, phosphatase and urease had a positive relationship with available N, P, K and organic carbon contents.

Changes in chemical and physical quality parameters of maize grain during three decades of yield improvement

Concern exists that the grain quality of maize ( Zea mays L.) may decline due to breeding for increased yield. This study quantified chemical- and physical-quality parameters of maize grain for hybrids representing three decades of grain yield improvement in Ontario, Canada. Six hybrids that were commercially important in Ontario from 1959 to 1988 were grown at two locations in southern Ontario during 1986 and 1987 at two plant densities. Grain contents of N, P, K, Ca, Mg, Zn, Cu, Mn, Se, lysine, tryptophan, and lipid were evaluated as chemical-quality parameters. Test weight, kernel density and weight, kernels exhibiting stress cracks, and breakage susceptibility were examined as indications of physical quality. Concentrations of Mg, Cu, Mn, and Se were greater in kernels of old hybrids than in more recent ones. Nitrogen concentration was greater in grain of recent hybrids and levels of N, P, and Mn all were lesser at high than at low plant density. Concentrations of lysine and tryptophan did not differ among hybrids. Differences in nutrient concentration were often greater among hybrids within an era than among means for eras of hybrid release. Among physical-quality traits, test weight, kernel density and kernel weight increased with more recent hybrids. These parameters were also higher with the lower plant density. Breakage susceptibility of kernels, although not affected by era of hybrid release, was less at low plant density.

The effect of stage of maturity on yield and quality of maize grain and stover

Stage of maturity at the time of harvest is considered as one of the factors influencing the nutritive value of crop residues. Thus this study was carried out to assess the effect of harvesting maize at different stages of grain maturity on yield and quality of maize grain and stover. The maize crop was harvested at grain moisture content of 28–30, 20–23 and 10–12%, which were designated as Stages I, II and III, respectively. Grain yield, standardised to 12.5% moisture content, showed an increasing trend, whereas cob, stover, total crop residue and total biomass dry matter (DM) yield showed a decreasing trend with increasing stage of maturity ( p>0.05). The declining trend in stover yield with increased stage of maturity was due mainly to leaf loss. There was a significant decrease ( p<0.05) in crop residue–grain ratio and leaf–stem ratio and a significant increase in the harvest index and hectolitre weight of the grain as the grain moisture content decreased from about 30 to 10%. Maize stover harvested at Stage I had significantly higher ( p<0.05) ash content than those harvested at Stages II and III. The crude protein (CP) content was significantly lower, whereas the neutral detergent fibre and cellulose contents were higher ( p<0.05) in Stage III than in Stages I and II. There was a decreasing trend in in sacco DM degradability with increasing stage of maturity. The washing loss, potential degradability and effective DM degradability at 0.03 h −1 rumen outflow rate were higher ( p<0.05) in Stage I than in Stages II and III. The volume of gas produced after 3, 6, 12, 24, 48 and 72 h of incubation was higher ( p<0.05) in Stage I than in Stages II and III. The a value (the intercept of the gas production curve) and the gas production potential ( a+ b) were higher ( p<0.05) in Stage I than in Stage III. Reduction in the nutritive value of stover with increasing stage of maturity was characterised by reduction in CP contents and increasing concentration of fibrous constituents. These were reflections of changes in the morphological composition of stover and losses of nutrients within the morphological fractions with increasing stage of maturity.

Genetic manipulations of protein quality in maize grain

This paper considers the main aspects of the genetic organization of the synthesis of zeins in maize endosperm. Recent advances in zein chemistry and biochemistry are discussed and the organization of zein structural genes is presented with particular emphasis on their arrangement within a multigene family. In addition, we present progress toward understanding the regulation of zein gene expression in relation to opaque loci. Finally, we focus our attention to genetic and molecular approaches for upgrading grain protein quantity and quality of maize grains.