The physical, chemical, and antioxidant properties of extrudates prepared from specialty tannin sorghum (CSC3xR28) and Tx430 black sorghums were evaluated. White food type sorghums (ATx631xRTx436) and commercial corn meal were also extruded. Sorghums were extruded as whole kernels or cracked (broken) kernels through a Maddox MX-3001 high-friction extruder. Cracked sorghum fortified with bran (0 -50%) derived from decortication or roller-milling were also extruded. Tannin sorghums extruded similarly to white food-type sorghums, with very little difference in extrudate quality. Cracking the sorghums produced lower feed rates, higher specific mechanical energy (SME) and extrudates that were less dense, more expanded, and softer than whole kernel extrudates. Whole and cracked sorghum materials had feed rates similar to corn meal, but lower SME. Corn meal extrudates were less dense, more expanded, and softer than sorghum extrudates. Cracked and whole black sorghum extrudates were less expanded than hi-tannin and white sorghum extrudates, due to the black sorghum's soft endosperm and thick, fibrous pericarp. With increased fiber, all extrudates had decreased SME and expansion, with increased bulk density and breaking force with the addition of bran. These effects, were more pronounced in extrudates containing decorticated bran vs. roller-milled bran. The decorticated bran had smaller particle size, higher density, lower endosperm content, and greater dietary fiber content than roller-milled bran. Also, increases in dietary fiber content in the extrudates were strongly correlated to increases in bran fortification in the raw feed stock. Tannin and black bran extrudates showed increased phenol, tannin (high-tannin), and antioxidants where bran was added. Phenols, tannins, and antioxidants in tannin extrudates ranged between 10.3-30.9 mg GAE/g, 7.1-55.2 CE mg/g, and 68.3-212.2 umol TE/g, respectively. Phenols and antioxidant activity in black sorghum extrudates ranged from 4.2 -7.8 mg GAE/g and 39.7 - 73.3 umol TE/g, respectively. Specialty tannin and black sorghums can be used to produce extruded snacks high in fiber and antioxidant activity. Optimum product characteristics, along with nutraceutical benefits, will need further determination.

As compared with other cereal grains, Sorghum bicolor shows very low levels ofprotein digestibility when exposed to proteolytic enzymes. Protein digestibility furtherdecreases when sorghum is cooked. It is speculated that low digestibility is the result ofextensive disulfide crosslinking in the - and -kafirins (storage proteins) surroundingthe endosperm protein bodies. The degree of crosslinking increases as sorghum iscooked, causing the highly digestible -kafirins found at the interior of protein bodies tobe locked within a tightly bound capsule, inaccessible to digestive enzymes. In thisresearch project, two major QTLs were found to be associated with proteindigestibility—one QTL unfavorably affecting digestibility and one QTL favorablyaffecting digestibility. By identifying the QTLs and the linked markers corresponding tothe highly digestible trait, breeders will be able to use marker-assisted selection toquickly and accurately identify highly digestible lines to advance in a breeding program.

The effect of currently used antioxidants and sorghum bran in pre-cooked beef patties was evaluated at two different fat levels (10 and 27%, w/w). Pre-formulated ground beef was purchased at a retail store on three different processing days. Within each fat level, ground beef portions were weighed and randomly assigned to control, butylated hydroxanisole (BHA) and butylated hydroxytoluene (BHT) (0.001%), rosemary (0.25%) or sorghum bran (0.25, 0.5 or 1.0%). After mixing in the appropriate antioxidant, 200-g patties were formed, and pH and objective color measurements for each raw patty were performed. Patties were cooked to an internal temperature of 73oC. Cooked patties were packaged and stored at 4oC. Two patties per treatment were sampled after 0, 1, 3 and 5 d of storage and analyzed for 2-thiobarbituric acid reactive substances (TBARS), non-heme iron, pH, instrumental color and trained flavor and texture descriptive attributes. The addition of BHA/BHT and rosemary extract to patties reduced non-heme iron, TBARS values, and cooked beef fat flavor attributes, but increased beef/brothy flavor attributes relative to control patties (P<0.05). As sorghum bran level increased, cooked beef patties were darker (P<0.05), less yellow (P<0.05), had higher non-heme iron (P<0.05), lower TBARS (P<0.05) and higher sandy/gritty (P<0.05) sensory texture. Cooked patties containing antioxidants did not differ in other sensory attributes (P>0.05). Fat mouthfeel of control patties were higher than treated patties (P<0.05). Sorghum bran delayed lipid oxidation by reducing TBARS values and cooked beef fat flavors, and when used at 0.25 and 0.5%, minimal effects on color and sensory attributes were observed. Our results suggested that sorghum bran can be a desirable natural antioxidant in pre-cooked ground beef.

An appropriate tester correctly identifies the relative performance of experimental lines while maximizing the differences between lines. Most sorghum breeding programs use elite inbred lines testers. Inbred line testers evaluate experimental lines against a specific genetic background, possibly increasing the probability of incorrectly discarding material. A potential solution would be to use F1 testers that combine two genetic backgrounds. The purpose of this research was to compare F1 testers versus inbred line testers for evaluating experimental sorghum lines in testcrosses Line x tester analyses were performed to assess tester consistency in assigning ranks. With one exception, all of the line x tester analyses were non-significant, indicating that the testers provided similar evaluations of the experimental lines. Correlations between the ranking of the experimental lines by their average performance and the rank assignments of each tester were measured to further asses tester accuracy. In all cases, the rank correlations were highly significant, implying that all of the testers accurately ranked experimental lines. In addition, all of the testers consistently identified the majority of the top performing experimental lines despite some important rank shifts. F-ratios for variance among the experimental lines (entry effect) were compared with the Schumann-Bradley statistical test to compare efficiencies. With one exception, the F1 testers always produced the largest or second largest entry effect F-ratio. Where the F1 testers produced the second largest F-ratio, it was not declared statistically different from the largest F-ratio by the Schumann-Bradley test, indicating that the testers had similar discriminatory efficiencies. Testcross variances were measured to further compare discriminatory efficiencies. With one exception, the F1 testers consistently produced the largest variances, evidence that the F1 testers were effective in maximizing differences among the experimental lines. The results indicate that F1 testers represent valid testers for evaluating experimental sorghum lines against two genetic backgrounds in a single testcross.

As compared with other cereal grains, Sorghum bicolor shows very low levels ofprotein digestibility when exposed to proteolytic enzymes. Protein digestibility furtherdecreases when sorghum is cooked. It is speculated that low digestibility is the result ofextensive disulfide crosslinking in the - and -kafirins (storage proteins) surroundingthe endosperm protein bodies. The degree of crosslinking increases as sorghum iscooked, causing the highly digestible -kafirins found at the interior of protein bodies tobe locked within a tightly bound capsule, inaccessible to digestive enzymes. In thisresearch project, two major QTLs were found to be associated with proteindigestibility—one QTL unfavorably affecting digestibility and one QTL favorablyaffecting digestibility. By identifying the QTLs and the linked markers corresponding tothe highly digestible trait, breeders will be able to use marker-assisted selection toquickly and accurately identify highly digestible lines to advance in a breeding program.

The Ma5 and Ma6 maturity loci in sorghum contain genes interacting epistatically to block flowering until an appropriate daylength is met. Because sorghum is a crop of tropical origin, its critical daylength is close to 12 hours. Sorghums with dominant alleles at these two loci are photoperiod sensitive, extremely late flowering, and ill-suited to cultivation in the temperate U.S. Most sorghum lines grown in the U.S. have been converted to photoperiod insensitive plants that have recessive mutations at the ma6 locus. This work describes ongoing efforts to clone the genes responsible for the Ma5/Ma6 â controlled late flowering response in sorghum. To reach this goal, the two loci were mapped with AFLP and SSR markers that were part of an integrated genetic, physical, and cytogenetic map of the sorghum genome. Genetic markers have been linked to both the Ma5 and Ma6 loci on chromosomes 2 and 6, respectively. BAC libraries have been screened to identify numerous BACs associated with each locus. Additional work to fine-map each locus and identify potential candidate genes by comparison with the rice genome is ongoing.

The physical, chemical, and antioxidant properties of extrudates prepared from specialty tannin sorghum (CSC3xR28) and Tx430 black sorghums were evaluated. White food type sorghums (ATx631xRTx436) and commercial corn meal were also extruded. Sorghums were extruded as whole kernels or cracked (broken) kernels through a Maddox MX-3001 high-friction extruder. Cracked sorghum fortified with bran (0 -50%) derived from decortication or roller-milling were also extruded. Tannin sorghums extruded similarly to white food-type sorghums, with very little difference in extrudate quality. Cracking the sorghums produced lower feed rates, higher specific mechanical energy (SME) and extrudates that were less dense, more expanded, and softer than whole kernel extrudates. Whole and cracked sorghum materials had feed rates similar to corn meal, but lower SME. Corn meal extrudates were less dense, more expanded, and softer than sorghum extrudates. Cracked and whole black sorghum extrudates were less expanded than hi-tannin and white sorghum extrudates, due to the black sorghum's soft endosperm and thick, fibrous pericarp. With increased fiber, all extrudates had decreased SME and expansion, with increased bulk density and breaking force with the addition of bran. These effects, were more pronounced in extrudates containing decorticated bran vs. roller-milled bran. The decorticated bran had smaller particle size, higher density, lower endosperm content, and greater dietary fiber content than roller-milled bran. Also, increases in dietary fiber content in the extrudates were strongly correlated to increases in bran fortification in the raw feed stock. Tannin and black bran extrudates showed increased phenol, tannin (high-tannin), and antioxidants where bran was added. Phenols, tannins, and antioxidants in tannin extrudates ranged between 10.3-30.9 mg GAE/g, 7.1-55.2 CE mg/g, and 68.3-212.2 umol TE/g, respectively. Phenols and antioxidant activity in black sorghum extrudates ranged from 4.2 -7.8 mg GAE/g and 39.7 - 73.3 umol TE/g, respectively. Specialty tannin and black sorghums can be used to produce extruded snacks high in fiber and antioxidant activity. Optimum product characteristics, along with nutraceutical benefits, will need further determination.

Sorghum grain with a waxy endosperm is more digestible and has a higher feeding efficiency compared to sorghum grain with a non-waxy (or normal) endosperm. However, waxy sorghums (Sorghum bicolor (L.) Moench) yield 10-15% less than normal sorghum and the cause of the yield reduction is unclear. The objective of this research is to determine if the yield decrease could be due to the waxy phenotype itself. The waxy phenotype is an example of a xenia effect, where the pollen not only contributes to the genotype of the resulting hybrid, but also immediately influences the phenotype of the resulting seed. Sterile hybrids under different pollination types, and different genotypes of fertile hybrids, both resulted in hybrids that produced different ratios of waxy phenotype seed. The effects on yield and 500 kernel weight were investigated in Weslaco, College Station, and Halfway, Texas over two years. Yields of sterile heterozygous waxy hybrids under waxy pollination, which produced an average 27% waxy seed over all environments, were nearly identical to homozygous nonwaxy hybrids that produced 0% waxy seed. Average 500 kernel weights for the same hybrids were not different. Grain yields for the fertile hybrid genotypes were significantlydifferent. Hybrids which produced 100% waxy seed yielded significantly less than hybrids which produced 25% waxy seed. Upon further examination, hybrids that were produced from waxy F1 endosperm seed (wxwxwx) had significantly worse stand and panicle number per plot means than did hybrids from nonwaxy F1 endosperm seed (Wxwxwx). Grain yields adjusted for panicle number showed no significant differences. The average 500 kernel weights between hybrids with different amounts of waxy phenotype grain did not significantly differ. The yield effect seen in this population was the result of waxy endosperm hybrid seed displaying significantly poorer stand establishment than nonwaxy endosperm hybrid seed. These data do not support a xenia yield effect due to the waxy gene.

Sorghum (Sorghum bicolor [L.] Moench) production in many areas of the world is reduced due to damage caused by sorghum midge (Stenodiplosis sorghicola). There are several methods of control to reduce losses due to sorghum midge, which include cultural practices, biological control, chemical control and resistant cultivars. The best long-term solution for sorghum midge control is the use of genetic resistance in cultivars and hybrids. Recently, sorghum midge resistant hybrids have been developed by several sorghum breeding programs, but there is limited information about agronomic performance relative to planting dates compared to susceptible standards. Thus, the objectives of this research project are: (1) to evaluate the value of sorghum midge resistant sorghum hybrids in the USA production system, (2) to confirm the presence of sorghum midge insect resistance in sorghum hybrids, and (3) to determine whether the resistance in eighteen sorghum hybrids is stable across two environments in Texas where sorghum midge is a damaging pest. Sorghum hybrids with different levels of resistance to sorghum midge were evaluated at College Station and Corpus Christi, Texas in 2003 and 2004, using two different planting dates and the presence or absence of an insecticide treatment. Agronomic data, sorghum midge incidence ratings and number of adult midges, were determined for all entries. All entries designated as resistant did have some resistance compared to susceptible checks. Across all hybrids, grain yield was higher in sorghum with normal planting dates compared to late planting. Under midge pressure resistant hybrids performed better than susceptible hybrids, but lacking midge pressure the susceptible hybrids were higher performing. The use of midge resistant hybrids in commercial production is only warranted when producers are reasonably sure that midge will be a problem. Otherwise, they should continue to plant early using traditional hybrids.

In sorghum, a predominantly self-pollinated crop, hybrid seed production relies exclusively on the cytoplasmic-genetic male sterility system. The system of hybrid development has caused sorghum breeding programs to develop two breeding groups: a male-parent group (R-line/ fertility-restorer) and a female-parent group (an A/B line, lacking the fertility-restoring gene of the A1 male-sterility system). These have served as heterotic groups in the absence of more information with reference to genetic diversity. Efforts to determine heterotic groups in sorghum have not been successful in clearly delineating any patterns. However, in a recent molecular marker-based study of 50 elite sorghum parental lines, groups similar to the working group system were observed, as was an absence of a consistent delineation, characteristic of heterotic groups, between the A/B- and R-lines. This study was conducted with the objective of evaluating the groups observed and assessing their potential as heterotic groups. Two parental lines from each of the five groups, and two lines from those not conforming to any group, were chosen and crossed in a half-diallel. The twelve parents, sixty-six diallel hybrids and three commercial hybrid checks were evaluated for grain yield and other agronomic traits in five environments' College Station, TX in 2003 and 2004, Weslaco, TX in 2003, and Halfway, TX in 2003 and 2004. Within-group crosses exhibited inferior heterotic expression, for grain yield and other traits, in comparison with across-group crosses. Furthermore, genetic similarity estimates for parental line pairs obtained from the molecular study were significantly correlated with specific combining ability and heterosis for yield of the corresponding hybrid combinations, revealing a pattern of correspondence between molecular data and heterosis. Hybrids made among R-lines and among B-lines were significantly lower in yield compared to AxR hybrids, likely to be a result of decades of breeding efforts to develop inbreds within the mutually isolated groups, rather than a consequence of phylogenetic divergence. An examination of the heterotic effects manifested in hybrid combinations reveals a pattern of interactions broadly in agreement with the molecular data, but differential responses between individual members of the proposed groups make it difficult to define distinct heterotic groups.