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Hunger is a problem faced by many people all over the world, and as the population grows, so does the need for food such as cereals. Because of this, the need for food with higher protein and nutrient content will be increasingly important. NAM-B1, a NAC-protein gene in wheat, has been shown to control the grain protein content and nutrient values, as well as senescence. In barley, two orthologous genes have been found, HvNAM1 and HvNAM2. This study focuses on Nordic barley accessions and how haplotypes of HvNAM1 and HvNAM2 correlate to the grain protein content (GPC) and nutrient content. No correlations between the different haplotypes of the HvNAM genes and the nutrient content and GPC were found. No differences in nutrient content and GPC were found in Nordic accessions originating from Sweden, Norway, Finland, or Denmark, nor were differences found for improvements status groups or for six-row barley and two-row barley. The Nordic accessions were shown to generally have high GPC when compared to control groups Karl and Lewis. However, even if the results of this study indicate that the HvNAM genes do not have major effects on the nutrient contents or GPC, Nordic barley might still be good material for plant improvement. Other factors such as other genes, environmental effects, and gene expression should therefore be investigated.

Revised 10/2015; Originally published 10/2013. / 2 pp. / Grain yield, test weight, and other characteristics of barley, durum, and wheat varieties are provided in this publication

Low grain protein content in durum can be prevented by applying nitrogen fertilizer after heading. Tentative guidelines were established from previous research for nitrogen fertilizer applications after heading based on the lower stem nitrate content near heading. Ten commercial durum fields were selected for testing the use of these guidelines to ensure grain protein contents greater than 13%. Only one field had grain protein content less than 13% (12.83%), and this field had herbicide damage and had to be over-irrigated due to surface unevenness. The average protein content was 13.62% but the amount of nitrogen fertilizer actually applied by the growers after heading averaged 74.5 lbs N/acre, whereas the amount recommended by the tentative guidelines averaged 53.1 lbs N/acre. If the tentative guidelines had been followed, we estimate that the average grain protein content would have been about 13.04%. Our tentative nitrogen fertilizer recommendations based on stem samples near heading appear accurate, but another year of testing would add more certainty.

Low grain protein content in durum can be prevented by applying nitrogen fertilizer after heading. Tentative guidelines were established from previous research for nitrogen fertilizer applications after heading based on the lower stem nitrate content near heading. Ten commercial durum fields were selected for testing the use of these guidelines to ensure grain protein contents greater than 13%. The average protein content was 14.00%, the amount of nitrogen fertilizer actually applied by the growers after heading averaged 44.5 lbs N/acre, whereas the amount recommended by the tentative guidelines averaged 41.5 lbs N/acre. If the tentative guidelines had been followed, we estimate that the average grain protein content would have been about 13.92%, and two fields would have been slightly below 13% protein (about 12.8% protein). Our tentative nitrogen fertilizer recommendations based on stem samples near heading appear accurate.

Low grain protein content in durum can be prevented by applying nitrogen fertilizer after heading. Tentative guidelines were established from previous research for nitrogen fertilizer applications after heading based on the lower stem nitrate content near heading. Three durum fields in Pinal County were selected for testing the use of these guidelines for ensuring grain protein contents greater than 13%. These fields were split into plots that either received late N fertilization after heading or not. The stem nitrate content at heading for two of the fields averaged 6337 ppm, indicating no need for late N fertilizer application to achieve grain protein content above 13%, and the grain protein content for these fields averaged 15.1% with or without late N fertilizer. The stem nitrate content at heading was 894 ppm for the third field, the stem nitrate guidelines called for a late N application of about 63 lbs N/a, and a late N application of 46 lbs N/a increased grain yield protein from 11.54 to 13.34%. Our tentative nitrogen fertilizer recommendations based on stem samples near heading appear accurate.

6 pp. / Guidelines for nitrogen fertilization of small grains are presented using crop need, calendar dates, or tissue testing. Relationship between grain protein and nitrogen fertilization is presented. Phosphorus, potassium, and other nutrients are also discussed.

In durum wheat (<i>Triticum turgidum</i> L. var <i>durum</i>), grain protein concentration (GPC) and gluten quality are among the important factors influencing pasta-making quality. Semolina with high protein content produces pasta with increased tolerance to overcooking and greater cooked firmness. However, genetic improvement of GPC is difficult largely because of its negative correlation with grain yield, and a strong genotype x environment interaction. Therefore, identification of quantitative trait loci (QTL) for high GPC and the associated markers is a priority to enhance selection efficiency in breeding durum wheat for elevated GPC. At a physiological level, GPC is influenced by several factors including nitrogen remobilization from vegetative organs and direct post-anthesis nitrogen uptake (NUP) from the soil. Understanding the relationship between elevated GPC and nitrogen remobilization, and post-anthesis NUP will enable durum wheat breeders to develop varieties that not only produce high yield and high GPC, but also exhibit better nitrogen use efficiency. The objectives of this study were: (1) to identify and validate QTL for elevated GPC in two durum wheat populations; and (2) to determine if elevated GPC is due to more efficient nitrogen remobilization and/or greater post-anthesis NUP. A genetic map was constructed with SSR and DArT® markers in a doubled haploid population from the cross Strongfield x DT695, and GPC data were collected in replicated trials in six Canadian environments from 2002 to 2005. Two stable QTL for high GPC, QGpc.usw-B3 on chromosome 2B and QGpc.usw-A3 on 7A, were identified. Strongfield, the high GPC parent, contributed the alleles for elevated GPC at both QTL. These two QTL were not associated with variation in grain weight (seed size) or grain yield. QGpc.usw-A3 was validated in a second Strongfield-derived population as that QTL was significant in all six testing environments. Averaged over five locations, selection for QGpc.usw-A3 resulted in a +0.4% to +1.0% increase in GPC, with only small effects on yield in most environments. A physiological study of grain protein accumulation revealed that regardless of the growing condition, nitrogen remobilization was the major contributor for grain nitrogen in durum genotypes evaluated, accounting for an average of 84.3% of total GPC. This study confirmed that introgression of Gpc-B1 into Langdon resulted in increased GPC, and this GPC increase was due to higher N remobilization. Strongfield expressed greater N remobilization than DT695 and the semi-dwarf cultivar Commander, but N remobilization was not the determining factor for Strongfields elevated GPC. Strongfield expressed greater post-anthesis NUP than DT695. Similarly, a selection of six high-GPC doubled haploid (DH) lines from the cross DT695 x Strongfield expressed significantly greater post-anthesis NUP than six low-GPC DH selections, supporting the hypothesis that elevated GPC in Strongfield is derived from greater post-anthesis NUP. All six high-GPC DH selections carried the Strongfield allele at QGpc.usw-A3, suggesting this QTL maybe associated with post-anthesis NUP.

In durum wheat (<i>Triticum turgidum</i> L. var <i>durum</i>), grain protein concentration (GPC) and gluten quality are among the important factors influencing pasta-making quality. Semolina with high protein content produces pasta with increased tolerance to overcooking and greater cooked firmness. However, genetic improvement of GPC is difficult largely because of its negative correlation with grain yield, and a strong genotype x environment interaction. Therefore, identification of quantitative trait loci (QTL) for high GPC and the associated markers is a priority to enhance selection efficiency in breeding durum wheat for elevated GPC. At a physiological level, GPC is influenced by several factors including nitrogen remobilization from vegetative organs and direct post-anthesis nitrogen uptake (NUP) from the soil. Understanding the relationship between elevated GPC and nitrogen remobilization, and post-anthesis NUP will enable durum wheat breeders to develop varieties that not only produce high yield and high GPC, but also exhibit better nitrogen use efficiency. The objectives of this study were: (1) to identify and validate QTL for elevated GPC in two durum wheat populations; and (2) to determine if elevated GPC is due to more efficient nitrogen remobilization and/or greater post-anthesis NUP. A genetic map was constructed with SSR and DArT® markers in a doubled haploid population from the cross Strongfield x DT695, and GPC data were collected in replicated trials in six Canadian environments from 2002 to 2005. Two stable QTL for high GPC, QGpc.usw-B3 on chromosome 2B and QGpc.usw-A3 on 7A, were identified. Strongfield, the high GPC parent, contributed the alleles for elevated GPC at both QTL. These two QTL were not associated with variation in grain weight (seed size) or grain yield. QGpc.usw-A3 was validated in a second Strongfield-derived population as that QTL was significant in all six testing environments. Averaged over five locations, selection for QGpc.usw-A3 resulted in a +0.4% to +1.0% increase in GPC, with only small effects on yield in most environments. A physiological study of grain protein accumulation revealed that regardless of the growing condition, nitrogen remobilization was the major contributor for grain nitrogen in durum genotypes evaluated, accounting for an average of 84.3% of total GPC. This study confirmed that introgression of Gpc-B1 into Langdon resulted in increased GPC, and this GPC increase was due to higher N remobilization. Strongfield expressed greater N remobilization than DT695 and the semi-dwarf cultivar Commander, but N remobilization was not the determining factor for Strongfields elevated GPC. Strongfield expressed greater post-anthesis NUP than DT695. Similarly, a selection of six high-GPC doubled haploid (DH) lines from the cross DT695 x Strongfield expressed significantly greater post-anthesis NUP than six low-GPC DH selections, supporting the hypothesis that elevated GPC in Strongfield is derived from greater post-anthesis NUP. All six high-GPC DH selections carried the Strongfield allele at QGpc.usw-A3, suggesting this QTL maybe associated with post-anthesis NUP.

The effects of soil nutrient status on the performance of four South African wheat genotypes were investigated in a long-term fertilization experiment. The objective was to quantify the effects of soil fertility on yield, yield components, grain nitrogen content, grain protein yield, grain protein content, flour yield and bread-making quality. The relative contribution of main stems and tillers, as well as the contribution of first, second and third kernels in the spikelets to grain yield and grain protein content were determined. The interactive effects between photoperiod, temperature and vernalization on grain yield, yield components and grain protein content were also quantified. Increasing soil fertility increased grain yield and most components of yield, grain nitrogen content, grain protein yield, aboveground biomass and harvest index, but depressed mean kernel mass. Significant interactions between cultivar and soil fertility were observed for grain yield, grain number, kernel mass, protein yield, biomass and harvest index, indicating differences in cultivar ability to produce yield and quality. Within a cultivar, the main stem, first tiller and second tiller did not differ in mean grain protein content, indicating that late-maturing tillers do not affect the grain protein content of wheat. Grain protein content, flour yield, loaf volume, water absorption and mixograph peak mixing time varied with soil fertility. The interaction between cultivar and soil fertility was significant for the above mentioned parameters with the exception of mixograph peak mixing time, indicating wheat genotypes differences in bread-making quality potential. The potential ability of wheat cultivar Kariega to produce higher grain yield, protein yield and loaf volume in the K and P limiting soil fertility situations deserve further investigation. In a growth chamber study, the low temperature regimes and long photoperiod conditions resulted in the highest grain yield, number of grains, largest mean kernel size and highest grain protein content. / Dissertation (PhD)--University of Pretoria, 2003. / Plant Production and Soil Science / unrestricted