Granule size distribution of wheat starch is an important characteristic that can influence its chemical composition, which in turn may affect its functionality. The granule size distribution and chemical composition of soft wheat starches were characterized and compared and relationships among those properties were identified. Thirty‐four starch samples from 12 soft wheat cultivars grown in the eastern half of the United States were examined. Granule size distribution was characterized using a laser light‐scattering technique. Amylose and phospholipid contents were determined using colorimetric procedures. A clear trimodal distribution of granule sizes was shown by 26 out of 34 starch samples: small granules with diameters <2.8 μm, midsize granules with diameters of 2.8–9.9 μm, and large granules with diameters >9.9 μm. Volume% distribution of granules within the three size classes had ranges of 9.7–15.2% (small), 13.4–27.9% (medium), and 57.9–76.9% (large). Highly significant differences were seen among the cultivars for volume% of granules within the ranges of 9.9–18.5 μm and 18.5–42.8 μm. Cultivar specific surface area means also differed. The environment affected granule size distribution, with some cultivars exhibiting more variation than others. Pioneer 2555 was the least variable, whereas Pioneer 2550 and Geneva were the most variable cultivars. Mean total amylose (TAM), apparent amylose (AAM), and lysophospholipid (LPL) values varied significantly among cultivars. TAM was positively correlated with the volume% of granules of 9.9–18.5 μm. LPL was negatively correlated with mean starch granule diameter and positively correlated with specific surface area of granules, indicating smaller granules tended to have higher lipid contents. Results suggest that significant differences exist in granule size distribution of soft wheat starches and affect starch chemical composition. Data also suggest it is possible that lipid is preferentially associated with the biosynthesis of small starch granules.

Soft wheat (Triticum aestivum L.) quality tests (milling and baking quality) and starch characteristics (amylose concentration, X-ray diffractograms, thermal properties and pasting properties) were determined for eight granule-bound starch synthase (GBSS: waxy protein) genotypes in a soft wheat background. Lines carrying two null alleles showed reduced amylose concentrations relative to those of single null and wild-type lines. Milling and baking quality traits were clearly different between waxy (triple null) and the other genotypes. Waxy lines showed the highest alkaline water retention (AWRC) capacity; even though, the protein concentration was not signi®cantly different from some double null and single null lines. The typical A-type patterns of X-ray diffractograms were observed for all starches. Waxy starch showed higher crystallinity than non-waxy starches. Analysis by Rapid Viscoanalyser (RVA) showed distinctive differences among the eight genotypes. Waxy starches showed higher peak viscosity, lower peak temperature and shorter peak time than those of all other genotypes. The results suggest that baking quality of waxy wheat can not be predicted by either AWRC or protein concentration. The interactions based on biochemical analysis between protein and other fractions (amylose and amylopectin, damaged starch) of partially and fully waxy wheat¯ours must be assessed before baking quality can be predicted. Furthermore, waxy wheat may not be suitable for current application of soft wheat products; however, distinct properties of waxy starch may open the possibility of commercial use in novel applications. Also, double null and single null genotypes may be a good source of variation for speci®c end-use products.

The confounding effect of wheat (Triticum aestivum L.) genetic background has been addressed as the major factor in inconsistent agronomic performances of 1RS translocation. The objective of this study was to test the effects of centric translocations of chromosome 1 in various rye (Secale cereal L.) sources on agronomic performance of wheat grown in humid southeastern conditions in North America. Various 1R substitution, 1RS translocation, and 1RL translocation lines in ‘Pavon 76’ were evaluated for agronomic performance. The 1RS translocation line was most favorable for agronomic performance when compared with those of substitution, 1RL translocation, and controls. The 1RS significantly increased grain yield. However, the effect of source of rye chromatin was greater than its position effect in wheat genome. Among translocation lines, those with 1RS derived from ‘E12165’ (CIMMYT) and ‘Amigo’ induced higher mean grain yield and T1DL·1RS derived from ‘BH1146/Blanco rye’ had the lowest grain yield. The mean grain yield of 1RL translocation lines was lower than that of 1R substitution. Thus, selection of 1RS source is important in producing constantly higher grain yield in 1RS translocation lines. Genetic recombination among different 1RS may also be used to create more genetic variation.

processing and end-use characteristics, which depend on protein hydration and development through mixing. Hybridizations between hard and soft wheat types could be a sourceHard wheat is generally used for making bread-type of novel variation for wheat quality improvement. This study was conducted to identify genomic regions related to differences in milling and products, and soft wheat is generally preferred for baking quality between a soft and a hard cultivar of hexaploid wheat pastry-type products. Hard grain requires more energy (Triticum aestivum L.). A population of 101 double-haploid lines was to be reduced to flour than soft grain, and its starch generated from a cross between Grandin, a hard spring wheat variety, granules are damaged more during milling. Damaged and AC Reed, a soft spring wheat variety. The genetic map included starch granules absorb more water, thereby altering sev-320 markers in 43 linkage groups and spanned 3555 cM. Quadrumateral baking properties (Mok and Dick, 1991). milled flour yield, softness equivalent, flour protein content and alkaline Hybridizations between hard and soft wheat types water retention capacity were evaluated for three locations and one year, could expand the genetic base of wheat breeding and and Allis-Chalmers milling, mixograph, and cookie baking tests were create new possibilities for combinations of desirable completed without replication. The effect of qualitative variation for alleles from both germplasm subgroups. However, this kernel texture, caused by the segregation of the Hardness gene, was controlled by regression on texture class. The residual variance was used type of cross is not common practice in wheat breeding for composite interval mapping, and QTLs on 1A, 1B, 1A/D, 2A, 2B, because the two classes have distinct quality goals. 2D, 3A/B, 4B, 5B and 6B were detected. The effect of some QTLs was Carver (1996) compared interclass hybrids, backcrosses opposite to the direction expected on the basis of parental phenotypes. and progeny from a hard ϫ hard cross, and concluded The hard wheat parent contributed alleles favorable for soft wheat variethat the interclass crosses resulted in progenies with ties at QTLs on 1AS,L, 1BL-2, and 6B, whereas the soft parent contribhigher grain yield but lower flour yield and larger variuted alleles for higher protein content at QTLs on 2BL-1, 4B-1, and 6B ability for quality traits, and that recovering the quality and higher flour yield on 2BL-2 and 4B-2. These results indicated that profile of the hard type through intensive selection would hard ϫ soft wheat crosses have considerable potential for improving be feasible. Identification of quantitative trait loci (QTL) milling and baking quality of either class.related to quality differences between classes could help in planning complementary crosses and backcrosses, and in designing selection schemes to recover the quality char-