Starch, mainly composed of amylose and amylopectin, is the major nutrient in grain sorghum. Amylose and amylopectin composition affects the starch properties of sorghum flour which in turn determine the suitability of sorghum grains for various end uses. Partial least squares regression models on near infrared (NIR) spectra were developed to estimate starch and amylose contents in intact grain sorghum samples. Sorghum starch calibration model with a coefficient of determination (R2) = 0.87, root mean square error of cross validation (RMSECV) = 1.57% and slope = 0.89 predicted the starch content of validation set with R2 = 0.76, root mean square error of prediction (RMSEP) = 2.13%, slope = 0.93 and bias = 0.20%. Amylose calibration model with R2 = 0.84, RMSECV = 2.96% and slope = 0.86 predicted the amylose content in validation samples with R2 = 0.76, RMSEP = 2.60%, slope = 0.98 and bias = −0.44%. Final starch and amylose cross validated calibration models were constructed combining respective calibration and validation sets and used to predict starch and amylose contents in 1337 grain samples from two diverse sorghum populations. Protein and moisture contents of the samples were determined using previously tested NIR spectroscopy models. The distribution of starch and protein contents in the samples of low amylose (<5%) and normal amylose (>15%) and the overall relationship between starch and protein contents of the sorghum populations were investigated. Percent starch and protein were negatively correlated, low amylose lines tended to have lower starch and higher protein contents than lines with high amylose. The results showed that NIR spectroscopy of whole grain can be used as a high throughput pre-screening method to identify sorghum germplasm with specific starch quality traits to develop hybrids for various end uses.

Use of trifluoromethanesulfonamide (TFMSA), a male gametocide, increases the opportunities to identify promising B‐lines because large quantities of F1 seed can be generated prior to the laborious task of B‐line sterilization. Combining TFMSA technology with genomic selection could efficiently evaluate sorghum B‐lines in hybrid combination to maximize the rates of genetic gain of the crop. This study used two recombinant inbred B‐line populations, consisting of 217 lines, which were testcrossed to two R‐lines to produce 434 hybrids. Each population of testcross hybrids were evaluated across five environments. Population‐based genomic prediction models were assessed across environments using three different cross‐validation (CV) schemes, each with 70% training and 30% validation sets. The validation schemes were as follows: CV1—hybrids chosen randomly for validation; CV2—B‐lines were randomly chosen, and each chosen B‐line had one of the two corresponding testcross hybrids randomly chosen for the validation; and CV3—B‐lines were randomly chosen, and each chosen B‐line had both corresponding testcross hybrids chosen for the validation. CV1 and CV2 presented the highest prediction accuracies; nonetheless, the prediction accuracies of the CV schemes were not statistically different in many environments. We determined that combining the B‐line populations could improve prediction accuracies, and the genomic prediction models were able to effectively rank the poorest 70% of hybrids even when genomic prediction accuracies themselves were low. Results indicate that combining genomic prediction models and TFMSA technology can effectively aid breeders in predicting B‐line hybrid performance in early generations prior to the laborious task of generating A/B‐line pairs.

Six sorghum [Sorghum bicolor (L.) Moench] germplasm lines, Tx3483 through Tx3488 (Reg. no. PL-313 to PL-318, PI 698643 to PI 698648), are proposed for release by Texas A&M Agrilife Research. These lines were developed and tested by the Agrilife Research sorghum breeding and genetics program. Tx3483 through Tx3488 are pollinator parents that combine waxy endosperm with improved agronomic performance and grain functionality. In combination with a waxy endosperm seed parent, these lines produce waxy endosperm hybrids with consistently higher yield than the currently available waxy check hybrid. Additionally, some of these germplasms produce hybrids with improved grain composition and functional properties of the derived flour.

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Sorghum [Sorghum bicolor (L.) Moench] germplasm lines Tx3489 (Reg. no. GP-943, PI 698649) and Tx3490 (Reg. no GP-944, PI 698650) with yellow seed, favorable agronomics, and popping attributes in hybrid combinations were developed by the Texas A&M AgriLife Research sorghum breeding and genetics program in 2020. Compared with a grain sorghum hybrid check, these lines produced hybrids with similar agronomic performance and superior popping performance. In hybrid combinations, the two lines produced hybrids comparable to the agronomic productivity of standard grain sorghum hybrids. Additionally, these two lines produced hybrids with 84 and 78% popping efficiency, 9:1 and 7.4:1 expansion ratios and 0.35-and 0.34-cm 3 flake sizes. In contrast, the check hybrid produced grain with 74% popping efficiency, 6.3:1 expansion ratio and a 0.25-cm 3 flake. Ultimately these two lines produce grain sorghum hybrids with comparable agronomic productivity and superior popping performance. While these lines can be used as pollinator parents to produce grain sorghum hybrids for popping, they may also be a parent for the development of new pop sorghum parental lines.

Interest in the use of popped sorghum in food products has resulted in a niche market for sorghum hybrids with high popping quality but little work has been done to assess the relative effects of field processing methods of grain on popping quality. This study evaluated the relative effects of harvest moisture and threshing methods on the popping quality of sorghum grain. A grain sorghum hybrid with good popping quality was produced during two different years in Texas wherein it was harvested at two moisture levels (low and high) and grain was removed from panicles using five different threshing methods (hand, rubber belt, metal brushes and two metal concave bar systems). Years, harvest moisture content and threshing method influenced all three popping quality measurements (popping efficacy, expansion ratio and flake size), but threshing method had an order of magnitude larger effect than either moisture level or year. While many of the interactions were significant, they did not influence the general trends observed. As such, the threshing methods with less direct impact force on the grain (hand and rubber belt) had higher popping quality than those samples threshed with greater impact force on the grain (metal-based systems). The popping quality differences between threshing system are likely due to a reduction in kernel integrity caused by the impacts to the kernel that occurred while threshing the grain. The results herein indicate that field processing of the grain, notably threshing method has significant impacts on the popping quality and should be taken into consideration when grain sorghum is harvested for popping purposes.

Grain weathering in grain sorghum [Sorghum bicolor (L.) Moench] is a persistent concern for producers in warm and humid climates. Further, grain sorghum genotypes are known to vary in their response to grain weathering; in some cases, this response is associated with a specific grain trait. For example, waxy endosperm sorghum is perceived to be more susceptible to grain weathering. This study herein compared waxy, heterozygous waxy, and non-waxy sorghum hybrids grown in multiple environments for grain weathering susceptibility and characterization of the fungal communities on the grain. The traits used to evaluate grain weathering included first grain weathering rating (FGWR), area under the disease progress curve (AUDPC), initial germination (IG), and reduction in germination (RIG). Grain weathering intensity varied among the tested environments; increased weathering occurred with wetter conditions. In combined analyses, the environment accounted for more variation (70.2, 38.2, 39.9, and 81.1%) than did genotype (9.0, 26.9, 15.8, and 5.0%) for FGWR, AUDPC, IG, and RIG, respectively. In only one of the four environments were the waxy and heterozygous waxy hybrids statistically different from the non-waxy genotypes. Ultimately, variation was more associated with genotypes than endosperm classes. Overall, Alternaria spp., Bipolaris spp., Fusarium semitectum, Curvularia spp., and Aspergillus niger were the most frequently observed pathogens across environments. Within an environment, the percent of different fungal pathogens remained relatively constant, but varied across environments.There was no clear distinction between either the level of grain weathering or the presence of a particular pathogen and endosperm type. The results indicate that grain sorghums with waxy endosperm are no more susceptible to grain weathering than those with normal, non-waxy endosperm.

Growth in the niche market of popped grain sorghum [Sorghum bicolor (L.) Moench] has increased the demand for grain sorghum lines or hybrids with improved popping quality. While there is a clear morphological difference in kernel morphology between popcorn [Zea mays L. everta] and most other types of corn, most grain sorghum genotypes have kernels with generally similar morphological structure. The absence of a specific kernel morphology for sorghum makes it impossible to eliminate types of grain sorghum that will not pop based solely on that morphology. Consequently, screening of any sorghum genotype requires the actual popping of grain from that genotype. As such, the identification of traits or combinations thereof that effectively screen grain sorghum genotypes for popping efficiency (PE), expansion ratio (ER), flake size (FS), and popped density (PD) is necessary. Herein, grain from 78 diverse genotypes grown in two environments were characterized for physical (i.e., diameter, thousand kernel weight, kernel hardness index, test weight, and visual hardness rating), compositional (i.e., starch, fiber, fat, ash, and protein), and popping characteristics (i.e., PE, ER, FS, and PD). No single physical or compositional trait was sufficiently correlated to prediction of popping performance. Multi-trait models better predicted popping performance than the single trait correlations. Further, multitrait models using compositional predictors increased prediction accuracies by 10.1% for PE, 42.9% for ER, 24.4% for FS, and 40.6% for PD compared with physical predictors. Among subgroups of genotypes, prediction accuracies varied considerably based on the criteria used to subdivide the genotypes. In conclusion, indirect selection for popping performance is possible by leveraging specific multi-trait models. INTRODUCTIONThe use of sorghum grain [Sorghum bicolor (L.) Moench] in food products has increased in the past ten years because of its neutral flavor, the absence of gluten, and the overall con-