Dry-season sorghum is a type of sorghum whose establishment ends at the end of the rainy season and its development takes place during the dry and cold harmattan period. Its root system is particularly well developed with deep penetration for water withdrawal. This study was conducted to assess the level of genetic diversity present among dry-season sorghum in Chad’s Sudanese zone using phenotypic traits, and to identify new sources of drought tolerance that could be used in sorghum breeding programs. A high variability in qualitative traits was observed except for the botanical race which showed that all cultivars were of durra race. It was also observed that most cultivars had compact panicles (66.67%), mostly black glumes (66.67%), glume hairiness (58.33%) and did not have aristation (91.67%). Most qualitative traits showed a coefficient of variation of less than 30%, and the analysis of the variance showed that at 0.1% probability, there were significant differences between cultivars for all traits except botanical race. It was observed that the potential productivity of dry-season sorghum of this collection was strongly related to their staygreen characteristic; a trait of enormous importance in breeding for postflowering drought tolerance in sorghum. Plant height was highly heritable (91.9%), followed by the peduncle length (90.2%), panicle length (87.5%) and the internodes number (86.5%). Structuring of diversity separated the cultivars into four statistically distinct groups; with group 2 clustering cultivars with panicle productivity, early maturity and high staygreen, and other traits that contribute to the performance of cultivars. The findings will help to enhance the selection and production of dry-season sorghum in Chad and also provide alternative sources for staygreen introgression into the larger sorghum breeding community.

The impact of drought stress on sorghum yield does not only depend on the intensity and timing of drought, but as well on the developmental stage of the crop. One of the limitations in breeding for pre-and/or postflowering drought stress resistance in sorghum is the less availability of diverse genetic sources possessing drought tolerant agro-morphological or physiological traits that could be introgressed into elite sorghum lines. This research evaluate a diverse group of 54 introgressed, converted, and commonly used sorghum breeding lines for their tolerance to field drought stress imposed at the pre-flowering and post-anthesis developmental stages in 2015 and 2016 growing seasons. Agro-morphological characteristics such as panicle area, panicle width, and percent green leaf and yield-related characteristics such as total above ground dry biomass and dry panicle weight were identified as significant predictors of grain yield under water stress. The current research identifies other sources that could be use by breeding programs as donor lines for traits related to pre-and postflowering drought tolerance in sorghum. Following statistical distribution and Tukey-Krammer HSD connecting letter tests, lines JB39, SC191, and SC270 and RIL R.11269 were identified as plausible sources for pre-flowering drought tolerance, and JB14, JB15, JB19, JB22, JB24, JB25, JB26, and JB33 as sources for the staygreen trait. While the staygreen is a good selection tool for postflowering drought tolerance, identifying staygreen lines with minimal reductions in grain yield and with earlier flowering dates (JB14, JB22, JB24 and JB25 in this study) than most commonly used staygreen donor lines, will ensure that grain yield is not over sacrificed by the ability of the crop to staygreen under terminal drought conditions.

Although cyanogenic glucosides are considered to play important roles in plant growth, development, and resistance against abiotic and biotic stresses, their presence in high concentrations in feed and food can be fatal to animals and humans. Sorghum [Sorghum bicolor (L.) Moench] is cyanogenic, and the cyanide potential varies with environmental factors, management, and genetic background. Acyanogenic lines have not been identified to date in natural collections. Although the variability of cyanide potentials in seedlings and leaves of plants at early growth stages has been highly researched, few works have looked beyond these stages, especially under variable environmental factors such as water deficit stress. Here, we evaluated 40 diverse sorghum lines for leaf dhurrin and soluble sugar content at various crop developmental stages and variable water availability. Five lines were identified with little‐to‐very low leaf dhurrin content across developmental stages and water availability. Leaves of 30‐d‐old sorghum plants had less cyanide potential than at later stages. A brief preflowering water stress, imposed at booting to flowering, decreased leaf dhurrin and soluble sugar contents, whereas a brief postflowering water stress or prolonged preflowering water stress increased dhurrin and soluble sugar contents. Rapid and efficient screening of dhurrin levels within existing sorghum germplasms could lead to the identification of additional lines with very low to nondetectable dhurrin levels, which will have an enormous impact on sorghum breeding and increase the agronomic value of the sorghum crop.

The Plant Genome S orghum is a major grain crop used for human consumption and animal feed as well as a promising bioenergy crop for sugar, biomass, and biofuel production (de Siqueira Ferreira et al., 2013; Rooney et al., 2007). Like maize (Zea mays L.), sorghum is a diploid C4 plant that, in contrast to maize, is well adapted to droughtprone and high-temperature environments and can thrive on marginal soils (Morris et al., 2013). Sorghum also has a much smaller genome than maize (~800 vs. 2500 Mb), and after the recent completion of a highquality diploid genome sequence, sorghum has become an emerging model for highly productive C4 crops (McCormick et al., 2018; Paterson et al., 2009). Heterosis, or hybrid vigor, the ability of hybrids to outperform the best inbred line parents is probably the most important strategy to increase grain yield in many crops including sorghum (Kim and Zhang, 2018). A critical requirement of using hybrids to increase yield is the ability to produce a pure male-sterile female parent that

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Vitamin C (Vit C) is an essential micronutrient and antioxidant for human health. Unfortunately, Vit C cannot be produced in humans and is ingested through diet while severe deficiencies can lead to scurvy. However, consumption is often inconsistent, and foods vary in Vit C concentrations. Biofortification, the practice of increasing micronutrient or mineral concentrations, can improve the nutritional quality of crops and allow for more consistent dietary levels of these nutrients. Of the three leading biofortification practices (i.e., conventional, transgenic, and agronomical), the least explored approach to increase Vit C in microgreens is agronomically, especially through the supplemental application of ascorbic acid. In this study, biofortification of Vit C in microgreens through supplemental ascorbic acid was attempted and proven achievable. Arugula (Eruca sativa 'Astro') microgreens were irrigated with four concentrations of ascorbic acid and a control. Total Vit C (T-AsA) and ascorbic acid increased in microgreens as supplementary concentrations increased. In conclusion, biofortification of Vit C in microgreens through supplemental ascorbic acid is achievable, and consumption of these bio-fortified microgreens could help fulfill the daily Vit C requirements for humans, thereby reducing the need for supplemental vitamins.

Early planted sorghum usually experiences cooler day/night temperatures, which may result in delayed growth, floral initiation, and infertile pollen, limiting productivity in high altitudes and temperate regions. Genetic variability for cold tolerance in sorghum has been evaluated by characterizing germination, emergence, vigor, and seedling growth under sub-optimal temperatures. However, the compounded effect of early season cold on plant growth and development and subsequent variability in potential grain yield losses has not been evaluated. Agro-morphological and physiological responses of sorghum grown under early-, mid-, and standard planting dates in West Texas were characterized from seed-to-seed. A set of diverse lines and hybrids with two major sources of tolerance, and previously selected for seedling cold tolerance were used. These were evaluated with a standard commercial hybrid known for its seedling cold tolerance and some cold susceptible breeding lines as checks. Variabilities in assessed parameters at seedling, early vegetative, and maturity stages were observed across planting dates for genotypes and sources of cold tolerance. Panicle initiation was delayed, and panicle size reduced, resulting in decreased grain yields under early and mid-planting dates. Coupled with final germination percent, panicle width and area were significant unique predictors of yield under early and mid-planting dates. Significant variability in performance was observed not only between cold tolerant and susceptible checks, but noticeably between sources of cold tolerance, with the Ethiopian highland sources having lesser yield penalties than their Chinese counterparts. Thus, screening for cold tolerance should not be limited to early seedling characterization but should also consider agronomic traits that may affect yield penalties depending on the sources of tolerance.

The USDA-ARS has released a new dwarf sorghum [Sorghum bicolor (L.) Moench) mutant BTx623 dw5 (Reg. No. GS-787, PI 688506). Dwarf genes have been an important driving force in breeding since the Green Revolution. Single dwarf locus is used to breed high-yielding semidwarf wheat (Triticum aestivum L.) and rice (Oryza sativa L.) cultivars. However, in sorghum, any of the known dwarf loci alone are insuicient to breed semidwarf grain sorghum itting for modern farm practices. Therefore, four dwarf loci have been traditionally used collectively in combinations to breed sorghum cultivars of the desired plant height for machine harvesting. Here we register a new sorghum dwarf mutant isolated from a mutagenized BTx623 mutant library, which is genetically diferent from those currently known controlling the dwarf phenotype in sorghum. Therefore, we designated this newly identiied dwarf genotype as dwarf 5 (dw5). The dwarf phenotype of dw5 was evaluated in two environments: the Puerto Rico winter nursery with short days and mild temperature conditions and the Lubbock, TX, summer ield with long days and high temperature conditions. The dw5 mutation reduced the plant height of BTx623 from 155 to 74 cm in Puerto Rico and from 113 to 72 cm in Lubbock. The dwarf phenotype in dw5 mutant is caused by a single nuclear gene mutation and is inherited in a recessive manner. It can be easily identiied and bred into other sorghum lines through recurrent backcrossing. The dw5 mutation provides a new way to control sorghum height.