Academic literature on the topic 'Grain quality'

Doctor of Philosophy<br>Department of Agronomy<br>Jianming Yu<br>Knowledge of the genetic bases of grain quality traits will complement plant breeding efforts to improve the end use value of sorghum (Sorghum bicolor (L.) Moench). The objective of the first experiment was to assess marker-trait associations for 10 grain quality traits through candidate gene association mapping on a diverse panel of 300 sorghum accessions. The 10 grain quality traits were measured using the single kernel characterization system (SKCS) and near-infrared reflectance spectroscopy (NIRS). The analysis of the accessions through 1,290 genome-wide single nucleotide polymorphisms (SNPs) separated the panel into five subpopulations that corresponded to three major sorghum races (durra, kafir, and caudatum), one intermediate race (guinea-caudatum), and one working group (zerazera/caudatum). Association analysis between 333 SNPs in candidate genes/loci and grain quality traits resulted in eight significant marker-trait associations. A SNP in starch synthase IIa (SSIIa) gene was associated with kernel hardness (KH) with a likelihood ratio–based R[superscript]2 (R[subscript]L[subscript]R[superscript]2) value of 0.08. SNPs in starch synthase (SSIIb) gene (R[subscript]L[subscript]R[superscript]2 = 0.10) and loci pSB1120 (R[subscript]L[subscript]R[superscript]2 = 0.09) was associated with starch content. Sorghum is a crop well adapted to the semi arid regions of the world and my harbor genes for drought tolerance. The objective of second experiment was to identify quantitative trait loci (QTLs) for yield potential and drought tolerance. From a cross between Tx436 (food grain type) and 00MN7645 (drought tolerant) 248 recombinant inbred lines (RILs) was developed. Multi-location trials were conducted in 8 environments to evaluate agronomic performance of the RILs under favorable and drought stress conditions. The 248 RILs and their parents were genotyped by genotyping-by-sequencing (GBS). A subset of 800 SNPs was used for linkage map construction and QTL detection. Composite interval mapping identified a major QTLs for grain yield in chromosome 8 and QTL for flowering time in chromosome 9 under favorable conditions. Three major QTLs were detected for grain yield in chromosomes 1, 6, and 8 and two flowering time QTLs on chromosome 1 under drought conditions. Six QTLs were identified for stay green: two on chromosome 4; one each on chromosome 5, 6, 7, and 10 under drought conditions.

The use of oats for human consumption is increasing every day due to the health benefits of oat products. With the objective to study relationships among factors affecting oat grain quality, two Recombinant Inbred Lines (RIL) mapping populations (`ND030299' x `ND991151' and `ND030299' x `Souris') have been used in this study. The two populations with their parents and three check cultivars were evaluated in a square lattice design in 2008 and 2009 at two North Dakota locations. Data were recorded on the following agronomic traits: grain yield, test weight, 1000 kernel weight, thin kernels, heading date, and plant height. Chemical and grain physical analysis were performed for ?-glucan, oil, and groat percentage. A total of 4975 SNP markers were assessed on the two populations using a 32-bead chip platform developed by Illumina. QTLs for agronomic and grain physical traits were mapped and characterized in the two populations using Windows QTL Cartographer. Grain yield was positively correlated with test weight, thin kernels, plant height, ?-glucan content, and associated negatively with 1000 kernel weight. Thirty linkage groups using 1168 polymorphic markers were formed for population 05021, whereas population 05026 comprised 33 linkage groups using 1024 polymorphic markers. The 30 linkage groups of population 05021 contained from 3 to 62 markers, and varied in size from 15.8 to 225.3 cM for a total map size of 2601.7 cM. The 33 linkage groups of population 05026 comprised from 2 to 42 markers, and varied in size from 2.3 to 143.2 cM for a total map size of 1174.2 cM. Nineteen genomic regions on 14 linkage groups were significantly associated with agronomic and grain chemical traits in the population 05021. Fourteen genomic regions on 12 linkage groups were identified for agronomic traits in the population 05026. The same genomic region on LG 05021-16 was associated with thin kernels, test weight, 1000 kernel weight, and oil content. LG 05026-19 loci, from position 23.7 to 47 cM, had strong effects on heading date, plant height, and grain yield. The QTLs consistently detected across environments and between the two populations could serve as starting points for marker-assisted selection.

The work presented here explores the effect of storage on chemical and other characteristics of dry, free of added chemicals and pest-free barley and canola grain. This was achieved by measuring the changes in a number of variables of grain stored at different temperatures under laboratory conditions and in commercial storage. The following measurements were carried out: Viability, moisture contents (mc), oil contents (oc), whole grain colour, spectrophotometry of grain extracts, hydroxy methyl furaldehyde (HMF), changes in storage atmospheres, organic sulphide levels, tocol concentrations (vitamin E), Iodine Value (IV), Thiocyanogen Value (TV), Peroxide Value (PV), p-Anisidine Value (p-AV) and Acid Value (AV). The mc of canola and barley were within the range considered safe for storage. Oil content of canola did not change significantly with storage. Viability of canola stored at 4 and 25 °C did not change noticeably, but higher storage temperatures resulted in seed death. Barley maintained high viabilities at low temperatures, but was more susceptible to high temperatures than canola. Colour changes of whole barley grain in storage were pronounced and temperature dependent. Colorimetry of whole barley grain showed potential as a tool for monitoring quality changes in storage. Absorption spectra of grain extracts reflected chemical and physiological changes in storage. HMF, an indicator of Maillard browning, accumulated in short to medium term storage at 45°C and in long term storage at 25 and 35°C. Measurement of HMF was considered useful for monitoring quality changes of stored cereal grain. In a study of storage atmospheres, changes in the concentrations of carbon dioxide, carbon monoxide, oxygen, carbon disulphide and carbonyl sulphide were shown to be useful indicators of quality loss of grain in storage. Gas concentrations usually depended on storage temperature and time and reflected the storage history of the commodity. They indicated loss of carbohydrates and lipids by respiration, oxidative damage and deterioration of sulphur containing amino acids and other compounds. Oil quality indicators were consistent with oxidative damage to canola lipids in storage. IV, TV, and p-AV of canola oil did not correlate with quality of commercial samples. However, a relationship between increases in PV and high storage temperatures in canola was shown and AV increased in storage dependent on storage temperature and time. In barley and canola, the concentration of anti-oxidant tocol species (vitamin E) decreased at 35 and 45°C storage dependent on storage time. The overall tocol content as well as vitamin E activity decreased with storage decreasing the nutritional value of the commodities and indicating oxidative damage to lipids. It was concluded that the storage of dry, pest-free whole barley and canola grain at moderate temperatures (25-45°C) resulted in chemical and other changes. The consequence of these changes was a measurable reduction in the freshness of grain relevant to the nutritional, food technological and commercial quality of grain.

Master of Science<br>Department of Agronomy<br>P.V. Vara Prasad<br>Sorghum (Sorghum bicolor L. Moench) is cultivated as an important food grain in the semi-arid regions of Africa. Processed grain sorghum is traditionally consumed as porridge, couscous, traditional tô or beer. The quality of such foods is highly dependent upon grain characteristics. Sorghum grain quality traits mainly include kernel hardness, kernel weight, kernel size, protein content and kernel color. Grain quality traits are often influenced by environment, genotypes, fertilizer management and their interaction. The objective of this study was to determine the impact of different levels of nitrogen application (0, 45, and 90 kg ha[superscript]-1) on grain quality of selected sorghum genotypes. The field experiment was conducted at three locations in 2010 (Manhattan, Ottawa, and Hays) and at two locations in 2011 (Manhattan and Ottawa). The experiment was laid in split plot randomized complete bloc design and replicated four times. The main plots were assigned to three N regimes: control (0 kg N ha[superscript]-1), half recommended rate (45 kg N ha[superscript]-1) and recommended rate (90 kg N ha[superscript]-1). The subplots were assigned to twelve genotypes (six hybrids and six inbred lines). Plot size was 6.1 m x 3.0 m with a row spacing of 0.75 m. After harvest, grain quality traits (hardness, weight, diameter and protein content) were evaluated using standard procedures and the data subjected to statistical design using SAS. There were significant effects of genotype for most grain quality traits across both locations in Manhattan. Inbred lines SC35 and SC599 had maximum hardness at all locations while hybrid 95207, had the lowest hardness for all locations. Also, Inbred lines SC35 and Tx340 had maximum protein content at all the locations. While hybrids 95207, 26056, 23012 had the lowest protein content. Genotypes Tx430, SC35, had higher hardness and with higher protein content were classified as high quality. We conclude that application of N (45 or 90 kg ha[superscript]-1) significantly improved grain protein, but not other quality traits. There are opportunities to improve grain protein through fertilizer management and plant breeding.

Triticale (X Triticosecale Wittmack) is a high-yielding and vigourous interspecific hybrid between wheat and cereal rye. The crop is known for tolerance of abiotic stresses and high biomass production, and thus it has the potential to increase the profitability and productivity of growers in marginal environments and to help address the food production challenges of the 21st century. The original cultivars from the 1960s and 1970s usually produced grain with flour properties in between triticale’s progenitor species, and thus produced dough inferior to wheat and unsuitable for a range of food products, including loaf bread, flat bread, cakes, biscuits and crackers. However over the last 40 years, grain yield and grain quality for animal feed have been significantly improved through breeding and selection, and hence indirect improvements (or at the least, genetic drift in quality alleles) in its potential to produce good food products could be expected. Furthermore, significant advances in wheat quality research have produced vast amounts of information, methodology and technology that can be easily used to improve triticale quality, and the tastes of the modern consumer are different to those of 40 years ago. This thesis aimed to characterise the flour properties of a range of modern triticale cultivars and compare them to wheat, then investigate genetic, agronomic and post-harvest strategies to improve the value of the grain for a human food market. Focus was given to the two major scientific issues which have historically hindered the use of triticale flour in food products – poor gluten strength and high α-amylase activity – and to other quality traits of commercial significance. The grain and flour quality was quantified in up to 17 modern triticale cultivars grown in four environments over 2 years – Greendale, NSW in 2009 (JP09), Cowra, NSW in 2010 (COW10), both of which are typical triticale growing environments with poor soil and minimal fertiliser, Narrabri, NSW in 2010 (NARR10), which is a high yielding, high quality environment known for producing Australian Prime Hard wheat, and Stirling, SA in 2011 (SA11) which is a high protein, low yielding environment. Field plots were arranged in a randomised complete block design at JP09, COW10 and NARR10 with minimal irrigation; rust was controlled with fungicide. The three varieties from SA11 were sourced from commercial seed production lots. Grain was milled to wholemeal flour on a Newport Scientific hammer mill with 0.5mm screen, and to white flour on both a Quadrumat® Junior Mill and a Bühler experimental mill. Glutenin and secalin subunits were characterised by SDS-PAGE and the gluten properties were investigated using the SDS-sedimentation test and mixographs. α-Amylase activity was investigated spectrophotometrically and using the falling number test. These vi measurements were compared to estimations of grain protein, non-starch polysaccharides (NSP), starch content and fibre content using near-infrared transmittance (NIT). Flour protein was estimated by NIR (near-infrared reflectance). The pasting properties of milled flours were evaluated on a Newport Scientific Rapid Visco Analyzer according to AACC 76-21, except 10 mM AgNO3 was used in place of DI water to inhibit α-amylase activity. Grain hardness was measured by the Single-Kernel Characterisation System and moisture and ash content by standard oven methods. Colour of Junior milled flour was assessed using a Minolta Chroma meter CR-400. Finally, plain cookies were baked according to a standard recipe used to assess soft wheats. Variability in the glutenin and secalin subunits was small relative to global diversity amongst triticale cultivars, and reflects the narrow genetic base of material in Australian breeding programs. The gluten quality of these triticale cultivars was inferior to bread wheat but similar to soft wheat; however the protein content of triticale flour was significantly lower than wheat flour. Lower triticale protein content represents a change from early cultivars and reduces its capacity to form viscoelastic gluten. Cultivars Hawkeye and Vicuna were recommended for breeding to improve gluten strength in locally adapted germplasm. Much greater variability in starch and NSP characteristics were found in triticale compared to wheat, and the ranges overlapped between species. The cultivars Tobruk, Yukuri and Berkshire expressed equivalent α-amylase activity to wheat; cultivars Jaywick and Yukuri were found to have partially waxy starch. Triticale generally exhibited higher NSP, equivalent pasting properties, higher α-amylase activity and lower falling number than wheat checks. However, low falling number was not indicative of high α-amylase activity; this contradicts the assumptions on which previous triticale research was based and has implications for the interpretation of research and the use of falling number to compare triticale to wheat. Furthermore, an unexpected negative correlation was observed with NSP, where higher NSP reduced the slurry viscosity measured in the falling number test. Modification of the falling number test is recommended before it can be used in triticale breeding programs. Nevertheless, the observed genetic variability in starch characteristics and α-amylase activity indicates some triticale cultivars have waxy properties conducive to the production of noodles, and that certain lines exhibited similar late-maturity α-amylase activity to modern wheat cultivars: an indirect benefit of breeding and selection over the past few decades. Like starch properties, great variation was found amongst triticale cultivars for hardness, colour and milling yield. Berkshire displayed a grain hardness equivalent to durum wheat, suggesting a null allele at the rye softness protein locus (Sin locus); the remaining cultivars exhibited a grain hardness between soft wheat and bread wheat. The high milling yield and low fibre content of Tobruk (milling yield was even higher than bread wheat) suggested this line has a thin seed coat and thus would be an excellent parent for the genetic improvement of triticale milling yield. Average flour ash content was significantly higher vii than wheat in both statistical and practical terms, and a different bench mark needs to be used for low ash triticale flour compared to low ash wheat. Apart from Vicuna and Yukuri, triticale cultivars produced darker flour than wheat, however with modern consumer preferences tending towards ‘healthy-looking’ foods, darker flour should not be a hindrance to its utility. The overall results confirmed previous suggestions that triticale is suited to soft wheat products such as cookies, and hence their cookie quality was investigated. Although the dough behaviour and water absorption of triticale was different to soft wheat (specifically, triticale dough tended to loose large amounts of water during sheeting), triticale cookies were found to be equivalent to soft wheat cookies. Overall, the survey of quality amongst modern triticale cultivars suggested two things: firstly, sufficient genetic variation exists amongst current lines to breed triticale cultivars with significantly improved flour quality (comparable to wheat for some quality traits); secondly, there is a clear need to classify current cultivars into suitability for various end uses. This would facilitate efficient marketing to the milling industry and subsequent use in food products. Improvement of the the poor gluten strength in triticale was attempted by backcrossing locally-adapted spring breeding lines to DH265, a winter line which contained a modified 1R chromosome carrying two translocations from 1D of bread wheat – the Glu-D1d allele from 1DL (which simultaneously removed Glu-R1) and the Gli-D1/Glu-D3 locus from the distal end of 1DS. Single plant and plot selection was performed on five cross populations grown in multiple environments and the yield, protein content and gluten strength was analysed on F4-derived F7 grain. Lines containing the translocation had a slightly lower yield compared to the null lines and the triticale checks; but similar to the wheat checks for all except one cross (which was significantly less). This may reflect a loss of root system vigour, head length or higher selection pressure due to lower transmission rate of the translocation to offspring. The translocation slightly increased protein content in two populations and increased SDS-sedimentation height in one population (after accounting for the influence of higher protein content). However, no difference was detected between the overall average SDS-sedimentation height of the null lines and the wheat and triticale checks. This is partially due to large variability in SDS-sedimentation height within each cross population resulting from significant variability at other glutenin and secalin loci. Nevertheless, several lines were identified with grain yield equivalent to current triticale cultivars (and significantly higher than wheat) plus equivalent SDS-sedimentation height to wheat. Thus the translocation is a potential solution to the generally poor gluten strength of modern triticale cultivars. The viability of using existing variability for secaloglutenin alleles in the progenitor species was investigated as a means of creating new germplasm (‘primary triticales’) with high gluten strength. The HMW glutenins of five durum lines, and the HMW secalins and 75k γ- secalins of two rye lines, were defined using SDS-PAGE. These lines were then crossed, new primaries were produced, and grain was tested for the expression of secaloglutenin viii alleles, protein content and SDS-sedimentation height as an estimation of secalogluten strength. The secaloglutenin alleles were simply inherited from the parental plants and all were expressed normally in the offspring, however it was possible that mixed oligomers were formed between glutenins and secalins at the macromolecular level. Significant differences were observed in the SDS-sedimentation height of primaries originating from different durum parents, suggesting that selection of durum parents with high SDSsedimentation is a viable method for producing triticale flour with superior gluten properties. In south-eastern Australia, dual-purpose cropping is commonly used by growers to manage risk in mixed enterprise operations. A preliminary report of lower ash content but comparable protein content in triticale produced in dual-purpose systems was reported in Bangladesh and hence an experiment was conducted to assess the effect of biomass removal on grain yield, test weight, protein content and ash content of grain from four Australian dual-purpose triticale lines grown in five year-site environments (ash content is correlated with nutritional value, milling yield and flour colour). Ash content was either unaffected or increased by removal of biomass and both protein content and grain yield were reduced. It was concluded that although ash content was lower in some lines cut late in the season, the general effect was detrimental to quality and even when ash content was reduced, the effect was not large enough to reduce the level to that of wheat. Hence similar to wheat, dual-purpose triticale systems are not recommended for production of grain for a milling market. Poor milling yield in triticale is a key concern for millers. However, the high variability of grain hardness in triticale, historic problems with grain shrivelling, and lack of varietal classification has meant milling is usually conducted without adjusting settings to batch characteristics. Hence the importance of tempering moisture was investigated in three triticale varieties of varying hardness grown in two environments alongside a wheat standard. Milling yield and ash content both increased as tempering moisture was decreased from 15% to 11%. Triticale flour could be produced at a similar extraction rate as bread wheat provided there was no detrimental effect of high flour ash content. Surface area of larger triticale grain may also influence ideal tempering moisture, however further investigation is required. Tempering triticale to a moisture content appropriate to its physical grain hardness was essential in the optimisation of the milling process. The results of this thesis suggests that it is possible to produce triticale cultivars with flour properties equivalent to wheat, either through traditional plant breeding, chromosomal modification or creation of new primary triticales. However, with a changing market, many of the flour requirements have changed since triticale was first investigated in food products e.g. increased popularity of darker/wholemeal flours. Furthermore, general improvement of the crop over the last few decades has indirectly improved the grain e.g. breeding for plump grain has increased starch content and milling yield. Many of the current concerns of millers such as insufficient protein content, sticky dough, high α- ix amylase production, and low milling yield, can be overcome through fertilizer management, classification of varieties into grain hardness, milling yield and protein quality classes, and sourcing batches of grain with low α-amylase activity (avoiding measurement using the falling number test). There is a clear need to develop a marketing pathway for triticale flour in which cultivars and agronomic conditions that optimise milling quality are clearly communicated to growers. This is a prerequisite for the establishment of a price premium for batches of grain that meet the requirements of millers, processers and consumers. The higher yield and abiotic stress tolerance of triticale suggests that with focused breeding and an industry-wide push for efficient flour marketing, this crop could address some of the food production challenges of the 21st century.