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Abstract Background As an important food and cash crop, identification of DNA molecular markers is of great significance for molecular marker-assisted breeding of Sorghum (Sorghum bicolor (L.) moench). Although some sorghum-related mutation databases have been published, the special SSR and SV databases still need to be constructed and updated. Results In this study, the quality of 18 different sorghum genomes was evaluated, and two genomes were assembled at chromosome level. Through the identification and comparative analysis of SSR loci in these genomes, the distribution characteristics of SSR in the above sorghum genomes were initially revealed. At the same time, five representative reference genomes were selected to identify the structural variation of sorghum. Finally, a convenient SSR/SV database of sorghum was constructed by integrating the above results ( http://www.sorghum.top:8079/ ; http://43.154.129.150:8079/ ; http://47.106.184.91:8079/ ). Users can query the information of related sites and primer pairs. Conclusions Anyway, our research provides convenience for sorghum researchers and will play an active role in sorghum molecular marker-assisted breeding.

Background: As an important food and cash crop, identification of DNA molecular markers is of great significance for molecular marker-assisted breeding of Sorghum (Sorghum bicolor (L.) moench). Although some sorghum-related mutation databases have been published, the special SSR and SV databases still need to be constructed and updated. Results: In this study, the quality of 18 different sorghum genomes was evaluated, and two genomes were assembled at chromosome level. Through the identification and comparative analysis of SSR loci in these genomes, the distribution characteristics of SSR in the above sorghum genomes were initially revealed. At the same time, five representative reference genomes were selected to identify the structural variation of sorghum. Finally, a convenient SSR/SV database of sorghum was constructed by integrating the above results (http://www.sorghum.top:8079/;http://43.154.129.150:8079/;http://47.106.184.91:8079/). Users can query the information of related sites and primer pairs. Conclusions: Anyway, our research provides convenience for sorghum researchers and will play an active role in sorghum molecular marker-assisted breeding. [ABSTRACT FROM AUTHOR]

Sorghum (Sorghum bicolor L.) a drought tolerant staple crop for half a billion people in Africa and Asia, an important source of animal feed throughout the world and a biofuel feedstock of growing importanceorghum's originated from tropical regions rendering the crop to be cold sensitive. Low temperature stresses such as chilling and frost greatly affect the agronomic performance of sorghum and limit its geographical distribution, posing a major problem in temperate environments when sorghum is planted early. Understanding the genetic basis of wide adaptability and of sorghum would facilitate molecular breeding programs and studies of other C4 crops. The objective of this study is to conduct quantitative trait loci analysis using genotying by sequencing for early seed germination and seedling cold tolerance in two sorghum recombinant inbred lines populations. To accomplish that, we used two populations of recombinant inbred lines (RIL) developed from crosses between cold-tolerant (CT19, ICSV700) and coldsensitive (TX430, M81E) parents. The derived RIL populations were evaluated for single nucleotide polymorphism (SNP) using genotype-by-sequencing (GBS) in the field and under controlled environments for their response to chilling stress. Linkage maps were constructed with 464 and 875 SNPs for the CT19 X TX430 (C1) and ICSV700 X M81 E (C2) populations respectively. Using quantitative trait loci (QTL) mapping, we identified QTL conferring tolerance to chilling tolerance at the seedling stage. A total of 16 and 39 total QTL were identified in the C1 and C2 populations, respectively. Two major QTL were identified in the C1 population, and three major QTL were mapped in the C2 population. Comparisons between the two populations and with previously identified QTL show a high degree of similarity in QTL locations. Given the amount of co-localization of QTL across traits and the direction of allelic effect supports that these regions have a pleiotropic effect. These QTL regions were also identified to be highly enriched for genes encoding chilling stress and hormonal response genes. This identified QTL can be useful in developing tools for molecular breeding of sorghums with improved low-temperature germinability. [ABSTRACT FROM AUTHOR]

Sorghum (Sorghum bicolor L.) a drought tolerant staple crop for half a billion people in Africa and Asia, an important source of animal feed throughout the world and a biofuel feedstock of growing importanceorghum’s originated from tropical regions rendering the crop to be cold sensitive. Low temperature stresses such as chilling and frost greatly affect the agronomic performance of sorghum and limit its geographical distribution, posing a major problem in temperate environments when sorghum is planted early. Understanding the genetic basis of wide adaptability and of sorghum would facilitate molecular breeding programs and studies of other C4 crops. The objective of this study is to conduct quantitative trait loci analysis using genotying by sequencing for early seed germination and seedling cold tolerance in two sorghum recombinant inbred lines populations. To accomplish that, we used two populations of recombinant inbred lines (RIL) developed from crosses between cold-tolerant (CT19, ICSV700) and cold-sensitive (TX430, M81E) parents. The derived RIL populations were evaluated for single nucleotide polymorphism (SNP) using genotype-by-sequencing (GBS) in the field and under controlled environments for their response to chilling stress. Linkage maps were constructed with 464 and 875 SNPs for the CT19 X TX430 (C1) and ICSV700 X M81 E (C2) populations respectively. Using quantitative trait loci (QTL) mapping, we identified QTL conferring tolerance to chilling tolerance at the seedling stage. A total of 16 and 39 total QTL were identified in the C1 and C2 populations, respectively. Two major QTL were identified in the C1 population, and three major QTL were mapped in the C2 population. Comparisons between the two populations and with previously identified QTL show a high degree of similarity in QTL locations. Given the amount of co-localization of QTL across traits and the direction of allelic effect supports that these regions have a pleiotropic effect. These QTL regions were also identified to be highly enriched for genes encoding chilling stress and hormonal response genes. This identified QTL can be useful in developing tools for molecular breeding of sorghums with improved low-temperature germinability.

Multi-environment trials (MET) are fundamental for assessing genotype-by-environment interaction (GxE) effects, adaptability and stability of genotypes and provide valuable information about target regions. As such, a MET involving grain sorghum hybrid combinations derived from elite inbred lines adapted to diverse sorghum production regions was developed to assess agronomic performance, stability, and genomic-enabled prediction accuracies within mega-environments (ME). Ten females and ten males from the Texas A&M and Kansas State sorghum breeding programs were crossed following a factorial mating scheme to generate 100 hybrids. Grain yield, plant height, and days to anthesis were assessed in a MET consisting of ten environments across Texas and Kansas over two years. Genotype plus Genotype-by-block-of-environment biplot (GGB) assessed ME, while the "mean-vs-stability" view of the biplot and the Bayesian Finlay–Wilkinson regression evaluated hybrid adaptability and stability. A genomic prediction model including the GxE effect was applied within ME to assess prediction accuracy. Results suggest that grain sorghum hybrid combinations involving lines adapted to different target regions can produce superior hybrids. GGB confirmed distinct regions of sorghum adaption in the U.S. Further, genomic predictions within ME reported inconsistent results, suggesting that additional effects rather than the correlations between environments are influencing genomic prediction of grain sorghum hybrids. [ABSTRACT FROM AUTHOR]

Sorghum (Sorghum bicolor [L.] Moench) is a valuable crop in the dry regions of the world, including Namibia. Due to the intensity and recurrence of drought and heat stress in the traditional sorghum growing areas, there is a need to breed and deploy new generation farmer-preferred and climate-smart cultivars to serve the diverse value chains. Therefore, the objectives of this study were to assess the present state of sorghum production in northern Namibia and document farmers' perceived production constraints and trait preferences in new varieties to guide drought-tolerance breeding. A survey was conducted using a participatory rural appraisal in the following six selected sorghum-growing constituencies in Namibia: Kapako and Mpungu (Kavango West Region), Eenhana and Endola (Ohangwena Region), and Katima Mulilo Rural and Kongola (Zambezi Region). Data were collected using a structured questionnaire involving 198 farmers in 14 sampled villages across the regions. Results revealed variable trends in sorghum production among respondent farmers when disaggregated by gender, age, number of households, education level, cropping systems, types of varieties grown, and perceived production constraints. An equal proportion of male and female respondent farmers cultivate sorghum, suggesting the value of the crop to both genders in Namibia. Most respondent farmers (63.6%) were in productive age groups of <40 years old. In the study areas, low-yielding landrace varieties, namely Ekoko, Okambete, Makonga, Kamburo, Nkutji, Katoma, Fuba, Dommy, Kawumbe, and Okatombo, were widely cultivated, and most of the farmers did not use chemical fertilizers to cultivate sorghum. Farmers' perceived sorghum production constraints in the study areas included recurrent drought, declining soil fertility, insect pest damage, high cost of production inputs, unavailability of improved seed, lack of alternative improved varieties with farmers' preferred traits, lack of organic manure, limited access to market and limited extension service. The key farmers' preferred traits in a new sorghum variety included high grain yield, early maturity, and tolerance to drought, in the field and storage insect pests. The study recommends genetic improvement and new variety deployment of sorghum with the described farmers-preferred traits to increase the sustainable production of the crop in Namibia. [ABSTRACT FROM AUTHOR]

Sorghum in Mexico ranks third in grain production. This study aimed to estimate general combining ability (GCA) and specific combining ability (SCA) for commercial and experimental sorghum grain parents and hybrids. The combining ability was estimated using the line x tester method described by Kempthorne. The experiment was established during the spring-summer 2018 cycle at INIFAP, Las Huastecas, México. It consisted of five lines, eight testers and 40 hybrids; in a randomized block design with three replications. The ANOVA showed highly significant differences for lines, testers, and line x testers, suggesting the existence of a broad base of genetic variability. GCA and SCA differences were statistically significant for grain yield, specific grain weight and plant height, indicating additive gene relevance, dominance and epistasis. For grain yield, the experimental lines: RB214A, RB225A and RB248A, and the testers RB133 and RB221, resulted significantly higher in GCA and superior to commercial RB225A line and RTx430 and RTx437 testers. Seventeen experimental hybrids were found to have significantly higher in SCA and were superior to INIFAP commercial hybrids. [ABSTRACT FROM AUTHOR]

Flood recession farming is an important cropping system for ensuring food security in western Mali. The present study identified sorghum varieties adapted to this farming system. In the first year, numerous varieties were tested in the fields of 12 farmers. The 22 best-performing varieties, based on farmers' scores using a preference index (PI), were further studied the following year. In the third year, the four varieties with the highest PI scores were tested against the local variety, Samé. The best-performing varieties were given the names Yélimané 1, Yélimané 2, Yélimané 3, and Yélimané 4. Across the three years, the best-performing variety, Yélimané 1, showed a 60.2% and 55.3% greater grain and stover yield, respectively, compared to the local Samé variety. The four improved varieties also reached maturity 30 days sooner than the local variety. A survey involving 101 farmers showed that the improved varieties, combined with higher plant density, seed priming and microdosing of mineral fertilizer, reduced the number of food-insecure months by 3.59 months. These varieties combined with improved agronomic practices have the potential to improve food security in flood recession areas in West Africa. [ABSTRACT FROM AUTHOR]

Flood recession farming is an important cropping system for ensuring food security in western Mali. The present study identified sorghum varieties adapted to this farming system. In the first year, numerous varieties were tested in the fields of 12 farmers. The 22 best-performing varieties, based on farmers’ scores using a preference index (PI), were further studied the following year. In the third year, the four varieties with the highest PI scores were tested against the local variety, Samé. The best-performing varieties were given the names Yélimané 1, Yélimané 2, Yélimané 3, and Yélimané 4. Across the three years, the best-performing variety, Yélimané 1, showed a 60.2% and 55.3% greater grain and stover yield, respectively, compared to the local Samé variety. The four improved varieties also reached maturity 30 days sooner than the local variety. A survey involving 101 farmers showed that the improved varieties, combined with higher plant density, seed priming and microdosing of mineral fertilizer, reduced the number of food-insecure months by 3.59 months. These varieties combined with improved agronomic practices have the potential to improve food security in flood recession areas in West Africa.

The sorghum breeding programs require to select and use of diverse cultivars to create genetic diversification. Therefore, the genetic variability among six sorghum cultivars was estimated by using twenty one SRAP primers combination and fourteen RAPD primers. The total number of amplified bands was 161 and 169 of which 94 and 148 polymorphic bands which appearing 58.4% and 87.6% polymorphism for SRAP and RAPD markers, respectively. Furthermore, the values of PIC (polymorphism information content) were accounted for each primer, to estimate the discriminatory vigor of the molecular markers for analysis of linkage and polymorphism. The PIC values for SRAP markers ranged from 0.60 by Me6 + Em6 to 0.15 by Me2 + Em3 and Me2 + Em4 with an average of 0.35 and the values of PIC for RAPD markers ranged from 0.81 by the OPP-08 primer to 0.41 by the OPE-20 primer. Similarity coefficients among the cultivars were ranged from 78.9% among Maka-244 and Horas cultivars to 61.3% among the Special-90 and Maka-244. The similarity coefficient was utilized to create a UPGMA based on pooled data from SRAP and RAPD analyses to illustrate the genetic distances among the six sorghum cultivars. These analyses demonstrated the power of SRAP and RAPD markers for estimating genetic diversification among sorghum cultivars. [ABSTRACT FROM AUTHOR]

High-yielding sorghum genotypes with farmer-preferred agronomic traits and durable anthracnose resistance are key drivers of productivity and adoption. The objective of this study was to determine combining ability effects and heterosis of selected sorghum lines for yield, yield-related traits, and anthracnose resistance, to identify superior parents and families for further selection and breeding. Nine selected sorghum genotypes with known resistance to anthracnose were crossed, using a 9 × 9 half-diallel mating design. Parents and F1 families were evaluated across two locations, using a randomized complete block design with three replications. Significant (P < 0.01) genotype, location, and genotype × location interaction effects were observed for most traits and anthracnose resistance, indicating mixed performances of the tested genotypes, allowing for further selection. General combining ability (GCA) and specific combining ability (SCA) effects were significant (P < 0.01) for most traits, including anthracnose resistance, indicating both additive and non-additive gene action underlying inheritance of the studied traits. Parental genotypes such as Bt-623, 210903, 234112, and 226057 showed positive and significant GCA effects for grain yield. Parents 74222, 214852, and 71708 showed negative and significant GCA for anthracnose resistance. The following families: Bt-623 × 210903, Bt-623 × 234112, Bt-623 × Chemeda, Bt-623 × Gemedi, 210903 × 234112, 210903 × 71708, 74222 × 234112, 74222 × 226057, 234112 × 71708, 226057 × 214852 and 226057 × 214852 expressing positive SCA effects for grain yield were identified. The following desirable families were selected: 174222 × 234112, Gemedi × 71708, Bt-623 × 234112, Bt-623 × Gemedi, 226057 × 71708, Chemeda × 71708, and Gemedi × 71708 with negative SCA effect and low anthracnose severity. These are useful sorghum populations for resistance breeding or direct production. [ABSTRACT FROM AUTHOR]

Abstract Sweet sorghum is a promising target for biofuel production. It is a C4 crop with low input requirements and accumulates high levels of sugars in its stalks. However, large-scale planting on marginal lands would require improved varieties with optimized biofuel-related traits and tolerance to biotic and abiotic stresses. Considering this, many studies have been carried out to generate genetic and genomic resources for sweet sorghum. In this review, we discuss various attributes of sweet sorghum that make it an ideal candidate for biofuel feedstock, and provide an overview of genetic diversity, tools, and resources available for engineering and/or marker-assisting breeding of sweet sorghum. Finally, the progress made so far, in identification of genes/quantitative trait loci (QTLs) important for agronomic traits and ongoing molecular breeding efforts to generate improved varieties, has been discussed.

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. [ABSTRACT FROM AUTHOR]

Genetic gain (GG), heritability and contribution of the agronomic traits on Al tolerance are precious information for selection strategy in the breeding of Al-tolerant sorghum. The objectives of this study were (i) to estimate the GG of Al tolerance in sorghum and (ii) to determine the direct effect of agronomic traits on Al tolerance through path analysis. Evaluation of agronomic characters used F2, and F3 sorghum progenies in field experiment and screening of Al tolerance used the hematoxylin-staining method. Three sorghum populations showed the low GG of Al tolerance (GG = 0.558–1.108). This result indicates that high allocation of progenies in the early stages of the Al-tolerant breeding program and high selection differential (sd) of Al tolerance should be applied to obtain a higher gain of Al tolerance. Selection pressure for early maturity (sd = −2.942) and short plant height (PH) (sd = −38.165) resulted in lower improvement of GG for Al tolerance. The high dry weight and tall PH provided a more genetic contribution to the advancement of Al tolerance. Based on the overall path analysis data, the increase of plant biomass, the significant number of progenies in the early stage of breeding and strong sd of Al tolerance would be more appropriate to improve the Al tolerance in sorghum. [ABSTRACT FROM AUTHOR]

Abstract One of the most frequently consumed sorghum food in Mali is a thick porridge, known as tô. Many grain traits contribute to its firmness and color, which are the most important qualities for consumers. These traits are related to chemical composition, physical properties, but also grain size, shape, glume adherence and color, pericarp thickness, or the presence of a testa. Quantitative trait loci for tô consistency, tô color, 16 grain traits, as well as day to flowering and grain yield, were investigated in two elite breeding populations, involved in a marker assisted selection program. A total of 51 and 71 QTLs were detected for P114 and P118, respectively. Several QTLs with high R2 corresponded to major genes segregating in the populations such as the Z gene for pericarp thickness, the B2 and B1 genes for testa presence, the P gene for anthocyanin, and a QTL for flowering time. Many QTLs with moderate effect were detected for grain attributes associated to tô quality, without showing antagonism between grain quality and yield. The results of this study will contribute to producing new varieties combining grain productivity and grain quality favorable alleles, through the use of marker assisted selection. Highlights • A QTL detection conducted in breeders' populations as part of a marker-assisted selection program. • Major genes with large effect still segregates in breeding population derived from elite material. • There is no major antagonism to jointly improve grain yield and grain quality in West-African sorghum germplasm. [ABSTRACT FROM AUTHOR]

Estimating genetic gains in sorghum [Sorghum bicolor (L.) Moench] is necessary to assess whether the current rates of improvement will meet future production demands. The current study was conducted to determine the rate of genetic gain in yield and associated traits over the commercial hybrid era using sorghum germplasm from the Texas A&M sorghum breeding program and a US sorghum seed company. From the Texas A&M AgriLife program, 60 hybrids that represented a 50-yr span of hybrid breeding were grown and evaluated in five environments across Texas in 2016. In a separate set of trials, 14 commercial hybrids representing a similar timespan were evaluated in three Texas environments in 2016. In both programs, grain sorghum yields increased 0.008 t ha-1 annually over their respective timespans. Traits that increased over time included yield potential per plant, heterosis, test weight, panicle size, and grain number per panicle, whereas leaf angle, days to maturity, plant height, and yield stability demonstrated little to no change. Overall, ~60% of total yield gains in US sorghum production are attributed to genetic improvement through sorghum breeding. Compared with other major US field crops, the rate of genetic gain in sorghum has been slower, presumably due to a combination of factors, which include continually shifting production environments, changing priorities in traits, reduced research investments (compared with other crops), and less-than-optimized heterotic groups. [ABSTRACT FROM AUTHOR]

The sugarcane aphid [SCA, Melanaphis sacchari (Zehntner), Hemiptera: Aphididae], is the predominant pest of US-grown sorghum [Sorghum bicolor (L.) Moench]. A previous study found that a single clone was prevalent on samples collected from sorghum in seven states and one territory of the United States in 2015. We sought to determine if this clone was still prevalent on sorghum grown in 2016 and if this clone is also found on Johnsongrass [S. halepense (L.) Pers.]. Forty-six SCA samples were collected from primarily sorghum and Johnsongrass from 10 cities in four states, and three aphid samples from different genera (Sipha, Rhopalosiphum, and Acyrthosiphon) were obtained. These aphid samples were genotyped with 43 SCA simple sequence repeat (SSR) markers. The predominant aphid clone found on sorghum in 2015 was again the predominant genotype in the 2016 SCA samples collected from sorghum. This same genotype was also found for the SCA samples collected from Johnsongrass in 2015 and 2016, although two samples differed at a single locus. Mixtures of this predominant genotype with three additional genotypes of SCAs were detected for three samples (excluding the control), indicating that multiple genotypes do exist in the United States but at low levels. This study provides evidence that a SCA "super-clone" has maintained its dominance on sorghum, and it is using the perennial Johnsongrass as an alternative host. [ABSTRACT FROM AUTHOR]

Sorghum (Sorghum bicolor L. Moench) is a C4 tropical grass that plays an essential role in providing nutrition to humans and livestock, particularly in marginal rainfall environments. The timing of head development and the number of heads per unit area are key adaptation traits to consider in agronomy and breeding but are time consuming and labor intensive to measure. We propose a two-step machine-based image processing method to detect and count the number of heads from high-resolution images captured by unmanned aerial vehicles (UAVs) in a breeding trial. To demonstrate the performance of the proposed method, 52 images were manually labeled; the precision and recall of head detection were 0.87 and 0.98, respectively, and the coefficient of determination (R 2) between the manual and new methods of counting was 0.84. To verify the utility of the method in breeding programs, a geolocation-based plot segmentation method was applied to pre-processed ortho-mosaic images to extract >1000 plots from original RGB images. Forty of these plots were randomly selected and labeled manually; the precision and recall of detection were 0.82 and 0.98, respectively, and the coefficient of determination between manual and algorithm counting was 0.56, with the major source of error being related to the morphology of plants resulting in heads being displayed both within and outside the plot in which the plants were sown, i.e., being allocated to a neighboring plot. Finally, the potential applications in yield estimation from UAV-based imagery from agronomy experiments and scouting of production fields are also discussed. [ABSTRACT FROM AUTHOR]

Highlights • Improved chilling stress phenotyping recommended for connecting chamber to field conditions. • Advanced breeding lines developed with increased chilling tolerance in desirable agronomic background. • Aerial phenotyping indices and destructive measurements correlated significantly. • Aerial HTP provides opportunities for phenotyping genetically large populations at high temporal frequency. Abstract Sorghum with greater chilling tolerance during early season has the potential to minimize terminal drought and heat stress damage and efficiently utilize early season residual moisture. Four promising chilling stress tolerant sorghum advanced breeding lines, a known early stage chilling tolerant Chinese landrace (Shan Qui Red - SQR) and a susceptible US elite cultivar (RTx430) as checks were assessed for chilling tolerance during emergence and early growth under field and controlled environments. Plants were exposed to a maximum day-time/minimum night-time temperature of 6/6°, 8/8°, 10/10°, 15/15°, 20/10°, 20/15° and 32/22 °C in two independent controlled environment growth chamber experiments. Field studies were conducted with two early (April 01 and 15) and regular (May 13 and June 02) plantings in 2016 and with one early (April 21) and regular (May 25) planting in 2017. Emergence rate and from seedlings harvested one month after emergence, leaf area, shoot weight, root weight, and other root morphological traits were recorded from all experiments. Aerial phenotyping using UAV fitted with multispectral camera was used to capture reflectance-based vegetation indices (NDVI and NDRE). Some advanced breeding lines recorded significantly better emergence, seedling growth and vigor, root biomass compared to SQR under chilling conditions. Aerial phenotyping indices from images taken between 30 and 60 days after emergence were consistently correlated with destructive measurements under early plantings, indicating their effectiveness in differentiating chilling responses. Aerial phenotyping indices have the potential to be utilized effectively for phenotyping genetically diverse populations for improving early season chilling tolerance in sorghum. [ABSTRACT FROM AUTHOR]

Purpose: Sorghum [Sorghum bicolor (L.) Moench] has been cultivated for centuries as a staple food crop for millions of people in sub-Saharan Africa and Asia. In Ethiopia a total of 4.34 million tons of sorghum is being produced per annum, predominantly in the arid and semi-arid areas. However, the yield and quality of sorghum is affected by a wide array of production constraints, notably severe and recurrent drought stress. The aim of this study were to determine the impact of drought on sorghum production and productivity over time and space, and to identify farmers’ trait preferences, production constraints and coping strategies when dealing with drought in north eastern Ethiopia.Materials and methods: Participatory rural appraisal (PRA) was employed in three administrative zones of north eastern Ethiopia. One Woreda from each Zone and two Kebeles from each Woreda were selected on the basis of sorghum area coverage, production, consumption and prior information on the intensity, duration and spatial coverage of drought. In each kebele, 30 respondents were selected for interview and 12 key informants were selected for group discussions and transect walk personal observations. Data collected from 180 respondents was subjected to statistical analysis and the information gathered from 72 key informants through focus group discussions and transect walk observations were used in discussing the results.Results and discussion: The present study found that productivity of sorghum was challenged by recurrent droughts, Striga infestation, insects, birds, diseases, a lack of varieties with farmers-preferred traits and high yield potential, limited policy support, a lack of improved seed system, poor sorghum production practices and application of crop input and poor soil fertility, in a decreasing order of importance. Among the listed sorghum production constraints, severe drought in the post-flowering stage was identified by most interviewed farmers as the leading constraint across the three study zones. Focus group discussions and transect walk observations held in each Kebele revealed that farmers’ had lost numerous valuable local landrace varieties due to extreme drought conditions over the years. A significant number of interviewed farmers preferred to grow high grain and biomass yielder medium-maturing sorghum varieties which can be sown at the normal planting time but which would escape post-flowering drought.Conclusion: Overall, sorghum breeding programme should be directed at developing farmers’ ideal sorghum varieties with high grain and biomass yield, adequate level of drought and Striga tolerance. In addition, development of farmer preferred medium-maturing sorghum varieties suitable for April planting should be strengthen to boost its productivity and to increase varietal adoption rate in the area. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

In West Africa Sudano-Sahelian zone, sorghum sensitivity to photoperiod is a major trait for flowering adjustment toward the end of the rainy season. This trait ensures that conditions for crop development are optimal. Improving the understanding of the genetic control of flowering time in sorghum is thus an important step toward breeding climate resilient varieties for meeting the challenge of climate smart agriculture. In the wake of green revolution, most sorghum breeders eliminated photoperiod sensitivity to develop early maturing varieties. The evidence is now that simultaneous improvement of production, yield stability and grain quality requires the development of photoperiod-sensitive varieties. A segregating sorghum population derived from a cross between two photoperiod sensitive elite parents was evaluated in three different locations and five environments. CERES crop model was applied to decompose the flowering time of each genotype into basic vegetative phase, critical photoperiod and photoperiod sensitivity. Phenology and model derived variables were used for genetic analysis. The three model parameters were controlled by specific genomic regions. A major QTL affecting critical photoperiod was identified, whereas only independent minor QTLs were found for basic vegetative phase and photoperiod sensitivity. Candidate gene analysis in the major QTL region allowed us to propose a candidate gene ( ELF3 ) involved in the circadian clock as a key regulator of flowering time in photoperiod-sensitive sorghum. Our findings provide critical information supporting the development of photoperiod-sensitive genotypes specifically adapted to climate variability encountered in Sudano-Sahelian zone. [ABSTRACT FROM AUTHOR]

Genomic selection can increase the rate of genetic gain in plant breeding programs by shortening the breeding cycle. Gain can also be increased through higher selection intensities, as the size of the population available for selection can be increased by predicting performance of nonphenotyped, but genotyped, lines. This paper demonstrates the application of genomic prediction in a sorghum [Sorghum bicolor (L.) Moench] breeding program and compares different genomic prediction models incorporating relationship information derived from molecular markers and pedigree information. In cross-validation, the models using marker-based relationships had higher selection accuracy than the selection accuracy for models that used pedigree-based relationships. It was demonstrated that genotypes that have not been included in the trials could be predicted quite accurately using marker information alone. The accuracy of prediction declined as the genomic relationship of the predicted individual to the training population declined. We also demonstrate that the accuracy of genomic breeding values from the prediction error variance derived from the mixed model equations is a useful indicator of the accuracy of prediction. This will be useful to plant breeders, as the accuracy of the genomic predictions can be assessed with confidence before phenotypes are available. Four distinct environments were studied and shown to perform very differently with respect to the accuracy of predictions and the composition of estimated breeding values. This paper shows that there is considerable potential for sorghum breeding programs to benefit from the implementation of genomic selection. [ABSTRACT FROM AUTHOR]

Thirty genotypes of forage sorghum were studied for generating information on nature and magnitude of genetic variability and diversity for designing breeding programme. The experiment was conducted in randomized complete block design in three replications. The data were recorded on days to 50% flowering, plant height, leaf breadth, leaf length, leaf area, stem girth, leaves per plant, leaf stem ratio, total soluble solids, protein content and green fodder yield. Analysis of variance revealed a substantial amount of variability among the genotypes for all the characters under study, indicated a wide spectrum of variability among the genotypes. Highest estimates of the phenotypic coefficient of variation and genotypic coefficient of variation were observed for plant height, leaf breadth, leaves per plant, leaf stem ratio and green fodder yield. High heritability coupled with high genetic advance was observed for plant height, leaf area, stem girth, leaves per plant, leaf stem ratio and green fodder yield. Based on D2 - Statistics, 30 genotypes were grouped into six clusters. The highest inter-cluster distance was observed between cluster III and VI followed by IV and VI, indicating genotypes included in these clusters had wide genetic diversity. Genetic divergence and cluster mean indicates maximum heterosis and good recombinants may be achieved in crosses between genotypes of clusters III, IV and VI in varietal improvement programme. Thus, crossing between genetically diverse genotypes of cluster III with genotypes CSV 15, PC 1001, SPV 462, PC 3, SSV 84, PC 8 and cluster VI with genotype HJ 513 are expected to exhibit high heterosis and good recombinants with desired traits. [ABSTRACT FROM AUTHOR]

A perennial version of grain sorghum [S. bicolor (L.) Moench] would create opportunities for greatly reducing tillage and preventing soil degradation. Efforts to select for perenniality and grain production among progeny of hybrids between S. bicolor (2n = 20) and the weedy tetraploid perennial S. halepense (L.) Pers. (2n = 40) are complicated in that F1 hybrids produced by diploid × tetraploid sorghum crosses are usually tetraploid. In 2013, a set of random pollinations between 19 diploid cytoplasmic male-sterile inbred lines and 43 tetraploid perennial plants produced 165 F1 hybrid plants, more than 75% of which had highly atypical plant, panicle, and seed phenotypes. Phenotypic segregation in F2 populations derived from atypical hybrids was also anomalous. Examination of mitotic metaphase cells in F1 or F2 root tips revealed that 129 of the 165 hybrids were diploid. Parentage of the diploid progenies was confirmed using simple-sequence repeat analysis. The mechanism by which diploid hybrids arise from diploid × tetraploid crosses is unknown, but it may involve either production of monohaploid (n = 10) pollen by the tetraploid parent or chromosome elimination during early cell divisions following formation of the triploid zygote. The ability to produce diploid germplasm segregating for S. bicolor and S. halepense alleles could have great utility, both for the development of perennial sorghum and for the improvement of conventional grain sorghum. [ABSTRACT FROM AUTHOR]

Multi-parent advanced generation intercross (MAGIC) populations are powerful nextgeneration mapping resources. We describe here the mating design and structure of the first MAGIC population in sorghum, and test its utility for mapping. The population was developed by intercrossing 19 diverse founder lines through a series of paired crosses with a genetic male sterile (MS) source, followed by 10 generations of random mating. At the final stage of random mating, 1000 random fertile plants in the population were identified and subjected to six generations of selfing to produce 1000 immortal MAGIC inbred lines. The development of this sorghum MAGIC population took over 15 yr. Genotyping-bysequencing (GBS) of a subset of 200 MAGIC lines identified 79,728 SNPs, spanning high gene-rich regions. Proportion of SNPs per chromosome ranged from 6 to 15%. Structure analyses produced no evidence of population stratification, portraying the desirability of this population for genome-wide association studies (GWAS). The 19 founders formed three clusters, each with considerable genetic diversity. Further analysis showed that 73% of founder alleles segregated in the MAGIC population. Linkage disequilibrium (LD) patterns depicted the MAGIC population to be highly recombined, with LD decaying to r2 ≤ 0.2 at 40 kb and down to r2 ≤0.1 at 220 kb. GWAS detected two known plant height genes, DWARF1 (chromosome 9) and DWARF3 (chromosome 7), and a potentially new plant height quantitative trait locus (QTL) (QTL-6) on chromosome 6. The MAGIC population was found to be rich in allelic content with high fragmentation of its genome, making it fit for both gene mapping and effective marker-assisted breeding. [ABSTRACT FROM AUTHOR]

Genetic improvement in sorghum breeding programs requires the assessment of adaptation traits in small-plot breeding trials across multiple environments. Many of these phenotypic assessments are made by manual measurement or visual scoring, both of which are time consuming and expensive. This limits trial size and the potential for genetic gain. In addition, these methods are typically restricted to point estimates of particular traits, such as leaf senescence or flowering and do not capture the dynamic nature of crop growth. In water-limited environments in particular, information on leaf area development over time would provide valuable insight into water use and adaptation to water scarcity during specific phenological stages of crop development. Current methods to estimate plant leaf area index (LAI) involve destructive sampling and are not practical in breeding. Unmanned aerial vehicles (UAV) and proximal-sensing technologies open new opportunities to assess these traits multiple times in large small-plot trials. We analyzed vegetation-specific crop indices obtained from a narrowband multi-spectral camera on board a UAV platform flown over a small pilot trial with 30 plots (10 genotypes randomized within 3 blocks). Due to variable emergence we were able to assess the utility of these vegetation indices to estimate canopy cover and LAI over a large range of plant densities. We found good correlations between the Normalized Difference Vegetation Index (NDVI) and the Enhanced Vegetation Index (EVI) with plant number per plot, canopy cover and LAI both during the vegetative growth phase (pre-anthesis) and at maximum canopy cover shortly after anthesis. We also analyzed the utility of time-sequence data to assess the senescence pattern of sorghum genotypes known as fast (senescent) or slow senescing (stay-green) types. The Normalized Difference Red Edge (NDRE) index which estimates leaf chlorophyll content was most useful in characterizing the leaf area dynamics/senescence patterns of contrasting genotypes. These methods to monitor dynamics of green and senesced leaf area are suitable for out-scaling to enhance phenotyping of additional crop canopy characteristics and likely crop yield responses among genotypes across large fields and multiple dates.

Sorghum (Sorghum bicolor L. Moench) is a promising novel crop for Central Europe. However, enhancements in cold tolerance and early maturity are essential for a successful adaptation to cooler climates. We scored a broad sorghum diversity set (n = 338) for early chilling tolerance, high-latitude adaptation, and bioenergy related agronomical traits in multi-environment trials. Our results show a high phenotypic variation and medium to high heritabilities for most traits, indicating that a robust breeding progress is feasible. Several public accessions with a good adaptation to cooler climates were identified, which can serve as valuable base material for sorghum breeding in temperate areas. Genome-wide association studies reveal a polygenic (quantitative) character for most of the traits, confirming previous studies. Hence, for practical breeding, it will be difficult to conduct efficient marker-assisted selection for temperate-adaptation traits in genetically diverse material.

Energy production from sorghum bioethanol is a way to help decrease climate change and environmental degradation. The objective of this work was to evaluate the agronomic characteristics associated to bioethanol production in experimental genotypes of sweet sorghum. During 2013 and 2014, seventeen sweet genotypes were evaluated in two locations, this locations are situated in northeastern Mexico, under a complete block randomly design with three replications. The three experiments were executed in Estacion Cuauhtemoc, Tamaulipas, in dryland; and two in Marin, Nuevo León, under irrigation. Experimental hybrid Potranca x Keller (p=0.05) presented the highest values (kg/ha) in: biomass weight (52 125), stem (39 650), panicle (4550), leaf (7700), juice (14 125), and bioethanol (2157 l/ha); it surpassed to the most productive control (Keller) in: 35,7, 32,5, 63,2, 41,6, 32,5, and 36,8%, respectively. It bloomed 6.8 days earlier than variety control. Experimental variety 17-1-1-1 had a minor foliar incidence of diseases in comparison to Keller. In addition, it presented agronomic characteristics similar to control in: biomass weight (44 375 kg/ha), stem (35 438 kg/ha), panicle (2488 kg/ha), leaf (6400 kg/ha), juice (11 750 kg/ha), plant dry weight (19 113 kg/ha), stem dry weight (14 888 kg/ha), bioethanol production (1929 l/ha), °Brix (15,2), days to flowering (80,8) and plant height (224 cm). [ABSTRACT FROM AUTHOR]

Forage sorghum (Sorghum bicolor (L.) Moench) is a very important fodder crop, therefore the improvement of this crop productivity is required. This study investigated the genetic variability among seven forage sorghum progenies in an experiment that was laid out as CRD in the greenhouse. The genetic diversity was assessed by using SSRs technique as well as some agronomical traits. The results showed that a number of grains per head can be used as an indicator of selection in breeding programs of this crop. However, SSRs result showed that there is variability among progenies under study and showed that the progeny 5 and 6 can be used in breeding programs, as they were very divergent. It can be concluded that there are variability of those progenies and can be utilized in further studies. It can be also recommended using large number of progenies as well as using more DNA-based markers. [ABSTRACT FROM AUTHOR]

Copyright of Tropical Grasslands / Forrajes Tropicales is the property of International Centre for Tropical Agriculture - CIAT and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Genetic improvement in sorghum breeding programs requires the assessment of adaptation traits in small-plot breeding trials across multiple environments. Many of these phenotypic assessments are made by manual measurement or visual scoring, both of which are time consuming and expensive. This limits trial size and the potential for genetic gain. In addition, these methods are typically restricted to point estimates of particular traits, such as leaf senescence or flowering and do not capture the dynamic nature of crop growth. In water-limited environments in particular, information on leaf area development over time would provide valuable insight into water use and adaptation to water scarcity during specific phenological stages of crop development. Currentmethods to estimate plant leaf area index (LAI) involve destructive sampling and are not practical in breeding. Unmanned aerial vehicles (UAV) and proximal-sensing technologies open new opportunities to assess these traits multiple times in large small-plot trials. We analyzed vegetation-specific crop indices obtained from a narrowband multi-spectral camera on board a UAV platform flown over a small pilot trial with 30 plots (10 genotypes randomized within 3 blocks). Due to variable emergence we were able to assess the utility of these vegetation indices to estimate canopy cover and LAI over a large range of plant densities. We found good correlations between the Normalized Difference Vegetation Index (NDVI) and the Enhanced Vegetation Index (EVI) with plant number per plot, canopy cover and LAI both during the vegetative growth phase (pre-anthesis) and at maximum canopy cover shortly after anthesis. We also analyzed the utility of time-sequence data to assess the senescence pattern of sorghum genotypes known as fast (senescent) or slow senescing (stay-green) types. The Normalized Difference Red Edge (NDRE) index which estimates leaf chlorophyll content was most useful in characterizing the leaf area dynamics/senescence patterns of contrasting genotypes. These methods to monitor dynamics of green and senesced leaf area are suitable for out-scaling to enhance phenotyping of additional crop canopy characteristics and likely crop yield responses among genotypes across large fields and multiple dates. [ABSTRACT FROM AUTHOR]

Background: In sorghum, the growth angle of nodal roots is a major component of root system architecture. It strongly influences the spatial distribution of roots of mature plants in the soil profile, which can impact drought adaptation. However, selection for nodal root angle in sorghum breeding programs has been restricted by the absence of a suitable high throughput phenotyping platform. The aim of this study was to develop a phenotyping platform for the rapid, non-destructive and digital measurement of nodal root angle of sorghum at the seedling stage. Results: The phenotyping platform comprises of 500 soil filled root chambers (50 × 45 × 0.3 cm in size), made of transparent perspex sheets that were placed in metal tubs and covered with polycarbonate sheets. Around 3 weeks after sowing, once the first flush of nodal roots was visible, roots were imaged in situ using an imaging box that included two digital cameras that were remotely controlled by two android tablets. Free software (openGelPhoto. tcl) allowed precise measurement of nodal root angle from the digital images. The reliability and efficiency of the platform was evaluated by screening a large nested association mapping population of sorghum and a set of hybrids in six independent experimental runs that included up to 500 plants each. The platform revealed extensive genetic variation and high heritability (repeatability) for nodal root angle. High genetic correlations and consistent ranking of genotypes across experimental runs confirmed the reproducibility of the platform. Conclusion: This low cost, high throughput root phenotyping platform requires no sophisticated equipment, is adaptable to most glasshouse environments and is well suited to dissect the genetic control of nodal root angle of sorghum. The platform is suitable for use in sorghum breeding programs aiming to improve drought adaptation through root system architecture manipulation. [ABSTRACT FROM AUTHOR]

Background: Quantitative trait loci (QTLs) detected in one mapping population may not be detected in other mapping populations at all the time. Therefore, before being used for marker assisted breeding, QTLs need to be validated in different environments and/or genetic backgrounds to rule out statistical anomalies. In this regard, we mapped the QTLs controlling various agronomic traits in a recombinant inbred line (RIL) population in response to Nitrogen (N) stress and validated these with the reported QTLs in our earlier study to find the stable and consistent QTLs across populations. Also, with Illumina RNA-sequencing we checked the differential expression of gene (DEG) transcripts between parents and pools of RILs with high and low nitrogen use efficiency (NUE) and overlaid these DEGs on to the common validated QTLs to find candidate genes associated with N-stress tolerance in sorghum. Results: An F7 RIL population derived from a cross between CK60 (N-stress sensitive) and San Chi San (N-stress tolerant) inbred sorghum lines was used to map QTLs for 11 agronomic traits tested under different N-levels. Composite interval mapping analysis detected a total of 32 QTLs for 11 agronomic traits. Validation of these QTLs revealed that of the detected, nine QTLs from this population were consistent with the reported QTLs in earlier study using CK60/China17 RIL population. The validated QTLs were located on chromosomes 1, 6, 7, 8, and 9. In addition, root transcriptomic profiling detected 55 and 20 differentially expressed gene (DEG) transcripts between parents and pools of RILs with high and low NUE respectively. Also, overlay of these DEG transcripts on to the validated QTLs found candidate genes transcripts for NUE and also showed the expected differential expression. For example, DEG transcripts encoding Lysine histidine transporter 1 (LHT1) had abundant expression in San Chi San and the tolerant RIL pool, whereas DEG transcripts encoding seed storage albumin, transcription factor IIIC (TFIIIC) and dwarfing gene (DW2) encoding multidrug resistance-associated protein-9 homolog showed abundant expression in CK60 parent, similar to earlier study. Conclusions: The validated QTLs among different mapping populations would be the most reliable and stable QTLs across germplasm. The DEG transcripts found in the validated QTL regions will serve as future candidate genes for enhancing NUE in sorghum using molecular approaches. [ABSTRACT FROM AUTHOR]

Key message : A flexible and user-friendly spatial method called SpATS performed comparably to more elaborate and trial-specific spatial models in a series of sorghum breeding trials. Abstract: Adjustment for spatial trends in plant breeding field trials is essential for efficient evaluation and selection of genotypes. Current mixed model methods of spatial analysis are based on a multi-step modelling process where global and local trends are fitted after trying several candidate spatial models. This paper reports the application of a novel spatial method that accounts for all types of continuous field variation in a single modelling step by fitting a smooth surface. The method uses two-dimensional P-splines with anisotropic smoothing formulated in the mixed model framework, referred to as SpATS model. We applied this methodology to a series of large and partially replicated sorghum breeding trials. The new model was assessed in comparison with the more elaborate standard spatial models that use autoregressive correlation of residuals. The improvements in precision and the predictions of genotypic values produced by the SpATS model were equivalent to those obtained using the best fitting standard spatial models for each trial. One advantage of the approach with SpATS is that all patterns of spatial trend and genetic effects were modelled simultaneously by fitting a single model. Furthermore, we used a flexible model to adequately adjust for field trends. This strategy reduces potential parameter identification problems and simplifies the model selection process. Therefore, the new method should be considered as an efficient and easy-to-use alternative for routine analyses of plant breeding trials. [ABSTRACT FROM AUTHOR]

Sweet sorghum is a promising target for biofuel production. It is a C4 crop with low input requirements and accumulates high levels of sugars in its stalks. However, large-scale planting on marginal lands would require improved varieties with optimized biofuel-related traits and tolerance to biotic and abiotic stresses. Considering this, many studies have been carried out to generate genetic and genomic resources for sweet sorghum. In this review, we discuss various attributes of sweet sorghum that make it an ideal candidate for biofuel feedstock, and provide an overview of genetic diversity, tools, and resources available for engineering and/or marker-assisting breeding of sweet sorghum. Finally, the progress made so far, in identification of genes/quantitative trait loci (QTLs) important for agronomic traits and ongoing molecular breeding efforts to generate improved varieties, has been discussed. [ABSTRACT FROM AUTHOR]

Field experiments to evaluate the split application of mesotrione + s-metolachlor, mesotrione + terbuthylazine, dicamba + prosulfuron, terbuthylazine + mesotrione + s-metolachlor, and sulcotrione in the cultivation of sorghum var. Rona 1 were carried out in 2012 and 2013. The field tests were conducted at the field experimental station in Winna Góra, Poznań, Poland. Treatments with the herbicides were performed directly after sowing (PE) and at leaf stage 1-2 (AE1) or at leaf stage 3-4 (AE2) of sorghum. The treatments were carried out in a laid randomized block design with 4 replications. The results showed that the tested herbicides applied at split doses were effective in weed control. After the herbicide application weed density and weed biomass were significantly reduced compared to the infested control. The best results were achieved after the application of mesotrione tank mixture with s-metolachlor and terbuthylazine. Application of split doses of herbicides was also correlated with the density, biomass, and height of sorghum. [ABSTRACT FROM AUTHOR]

Sorghum ( Sorghum bicolor L. Moench) is regarded a drought-tolerant alternative to maize as a bioenergy and fodder crop, but its early-stage chilling sensitivity is obstructing a successful implementation in temperate areas. While several studies have identified quantitative trait loci ( QTL) underlying chilling tolerance-related traits in sorghum lines, little is known about the inheritance of these traits in F1 hybrids. We have conducted a comprehensive approach to analyse heterosis, combining ability and the relation between line per se and hybrid performance for emergence and early shoot and root development comprising both field trials and controlled environment experiments including chilling tests. To our best knowledge, this is the first study analysing heterosis for sorghum root parameters under chilling. Our results show that most traits are heterotic and that the mid-parent values are rather poor predictors of hybrid performance. Hybrid breeding programmes should focus on efficient GCA tests and the establishment of genetically diverse pools to maximise heterosis rather than on a too strict selection among lines based on their per se performance. The medium-to-high heritabilities estimated for seedling emergence and juvenile biomass suggest that a robust breeding progress for these complex traits is feasible. [ABSTRACT FROM AUTHOR]

The present investigation in forage sorghum (Sorghum bicolor L. Moench) was carried for studying the magnitude of heterosis and inbreeding depression of forty five hybrids (F1s) and their F2s made by crossing of ten parents in a completely Randomized Block Design (RBD). Observations were recorded on quantitative and qualitative traits viz., days to 50 per cent flowering, plant height (cm), leaf breadth (cm), leaf length (cm), leaves per plant, leaf area (cm²), leaf stem ratio, stem girth (cm), total soluble solids (%), protein content (%) and green fodder yield (Kg/ha). Variable magnitude of three types of heterosis (better parent, mid-parent and standard) were observed for different cross combinations for all the traits. The high magnitude of heterosis and per se performance was found in hydrid SSG 59-3 x CSV 15 over better as well as economic parent for green fodder yield indicating that this cross can be exploited commercially. Nine crosses namely, SSG 59-3 x CSV 15, Pant chari 5 x CSV 15, RSSV 9 x HC 171, CSV 15 x UP chari 2, G 48 x UP chari 2, Pant chari 5 x HC 171, G 48 x HC 171, Pant chari 6 x CPVI 1724 and SSG 59-3 x Pusa chari 23 over better parent as well as economic parent may be exploited for developing hybrids for better yield in forage sorghum. Five crosses namely, Pusa chari 23 x G 48, Pusa chari 23 x CPVI 1724, Pant chari 5 x UP chari 2, Pant chari 5 x G 48 and Pant chari 6 x CPVI 1724 exhibited significant negative inbreeding depression in both the generations with additive type gene interaction may be suggested for increasing green fodder yield. [ABSTRACT FROM AUTHOR]

Heterosis and combining ability analysis of 10 x 10 diallel (excluding reciprocal) set of crosses in forage sorghum were done for yield and its contributing characters during the season of Kharif 2012 by raising the crop at Crop Research Center. All the 45 F1 hybrids and their ten parents were grown and selfed during Kharif season of 2013 for producing F2 seeds. All the 45 F1 hybrids and 45 F2 populations along with ten parents were sown in Randomized Block Design with three replication at Crop Research Center of Sardar Vallabhbhai Patel University of Agriculture and Technology, Meerut during the Kharif season of 2013. Observation were recorded on days to 50% flowering, plant height, leaf breadth, leaf length, leaves per plant, leaf area, leaf stem ratio, stem girth, total soluble solids, protein content and green fodder yield. ANOVA for combining ability revealed that the parent SSG 59-3 exhibited high general combining ability effect for all the characters except days to 50% flowering, leaf breadth, leaf stem ratio, stem girth, total soluble solids and protein content in both F1 and F2 generations. Promising parents viz., HC 171, UP chari 2, Pant chari 5 and Pant chari 6 which were having high general combining ability effects in desirable direction for green fodder yield and yield components character like plant height, leaf breadth, leaf length and stem girth may be incorporated in crossing programme to have better genotypes for better green fodder yield. The cross combinations namely, UP chari 2 x HC 171, Pant chari 5 x RSSV 9, Pant chari 5 x SSG 59-3, SSG 59-3 x Pusa chari 23, CSV 15 x Pant chari 6, G 48 x HC 171, CPVI 1724 x HC 171 and Pant chari 5 x G 48, which exhibited good specific combining ability effects for green fodder yield and its contributing traits such as days to 50% flowering, leaf breadth, leaf length, leaves per plant, leaf stem ratio and stem girth in both F1 and F2 generations. Nine cross combinations which revealed highest value of heterosis for leaves per plant and green fodder yield viz., SSG 59-3 x CSV 15, Pant chari 5 x CSV 15, RSSV 9 x HC 171, CSV 15 x UP chari 2, G 48 x UP chari 2, Pant chari 5 x HC 171, G 48 x HC 171, Pant chari 6 x CPVI 1724 and SSG 59-3 x Pusa chari 23 over better parent as well as economic parent may be exploited for developing hybrids for better yield in forage sorghum. [ABSTRACT FROM AUTHOR]

Background: Sorghum is mainly used as a human food and beverage source, playing an important role in the production of ethanol and other bio-industrial products. Thus it is regarded as a model crop for energy plants. Genetic map construction is the foundation for marker-assisted selection and gene cloning. So far several sorghum linkage maps have been reported using different kinds of molecular markers. However marker numbers and chromosome coverage are limited. As a result, it is difficult to get consistent results and the maps are hard to unify. In the present study, the genomes of 130 individuals consisting an F2 population together with their parents were surveyed using a high-throughput sequencing technique. A high-density linkage map was constructed using specific-locus amplified fragments (SLAF) markers. This map can provide information and serve as a reference for effective gene exploration, and for marker assisted-breeding program. Results: A high-throughput sequencing method was adopted to screen SLAF markers with 130 F2 individuals from a cross between a grain sorghum variety, J204, and a sweet sorghum variety, Keter. In the present study, 52,928 suitable SLAF markers out of 43,528,021 pair-end reads were chosen to conduct genetic map construction, 12.0% of which were polymorphic. Among the 6353 polymorphic SLAF markers, 5829 (91.8%) were successfully genotyped in the F2 mapping population. Finally 2246 SLAF markers were obtained to construct a high-density genetic linkage map. The total distance of linkage map covering all 10 chromosomes was 2158.1 cM. The largest gap on each chromosome was 10.2 cM on average. The proportion of gaps less than and/or equal to 5.0 cM was averagely 98.1%. The markers on each chromosome ranged from 123 (chromosome 9) to 315 (chromosome 4) with a mean value of 224.6, the distance between adjacent markers ranged from 0.6 (chromosome 10) to 1.3 cM (chromosome 9) with an average distance of only 0.98 cM. Conclusion: A high density sorghum genetic map was constructed in this study. The total length was 2158. 1 cM covering all 10 chromosomes with a total number of 2246 SLAF markers. The construction of this map can provide detailed information for accurate gene localization and cloning and application of marker-assisted breeding. [ABSTRACT FROM AUTHOR]

Sorghum (Sorghum bicolor L. Moench) is one of the most important grain crops in the world. The nuclear male sterility (NMS) trait, which is caused by mutations on the nuclear gene, is valuable for hybrid breeding and genetic studies. Several NMS mutants have been reported previously, but none of them were well characterized. Here, we present our detailed morphological characterization of a new and easily recognizable NMS sorghum mutant male sterile 8 (ms8) isolated from an elite inbred BTx623 mutagenized by ethyl methane sulfonate (EMS). Our results show that the ms8 mutant phenotype was caused by a mutation on a single recessive nuclear gene that is different from all available NMS loci reported in sorghum. In fertile sorghum plants, yellow anthers appeared first during anthesis, while in the ms8 mutant, white hairy stigma emerged first and only small white anthers were observed, making ms8 plants easily recognizable when flowering. The ovary development and seed production after manual pollination are normal in the ms8 mutant, indicating it is female fertile and male sterile only. We found that ms8 anthers did not produce pollen grains. Further analysis revealed that ms8 anthers were defective in tapetum development, which led to the arrest of pollen formation. As a stable male sterile mutant across different environments, greenhouses, and fields in different locations, the ms8 mutant could be a useful breeding tool. Moreover, ms8 might be an important for elucidating male gametophyte development in sorghum and other plants. [ABSTRACT FROM AUTHOR]

Contamination of agricultural fields with heavy metals, such as Cd, is a serious issue for safe food production worldwide. Previous reports indicate that sorghum [Sorghum bicolor (L.) Moench] is useful for phytoextraction of Cd from contaminated soils. To investigate the diversity for Cd accumulation in sorghum germplasm and to select useful cultivars for phytoextraction, we conducted experiments using 106 sorghum landraces and the cultivar BTx623, grown in hydroponic cultures and under field conditions. The Cd concentrations in plant shoots of different landraces showed no correlation between hydroponic and field-grown plants (r = −0.16). We measured Cd concentrations in various plant parts at different stages of development in field-grown plants and found that leaf sheaths often had higher Cd concentrations than other plant parts. Our results indicated that screening could be done for plants that might be useful for phytoextraction of Cd by determining the Cd concentrations in leaf sheaths of 1-mo-old plants grown in a Cd-contaminated soil. We also mapped the quantitative trait loci (QTLs) responsible for Cd accumulation in sorghum shoots and found several chromosomal regions that affected Cd concentrations in different parts of the shoot. We were able to identify several promising landraces for developing sorghum cultivars that are capable of accumulating high levels of Cd and phytoextracting Cd from contaminated soils. [ABSTRACT FROM AUTHOR]

Water scarcity still becomes a problem in some dryland agricultural areas in Indonesia. Development of dryland farming system may be focused on crops that are required less water such as sorghum. Sorghum is a cereal crop that is usually grown under hot and dry condition and it is ideal for Indonesia. Sorghum is a good source of food, animal feed and raw material for ethanol. Indonesia is currently looking for alternative renewable energy resources and sorghum is regarded as one of the promising source of bioethanol as bioenergy. Unfortunately, most agricultural land in western part of the country particularly in Sumatera and Kalimantan is dryland and dominated by acid soil. The main constraint of crop production in acid soil is deficiency and Al toxicity. Therefore, development of sorghum cultivation in dryland farming system requires a variety which is tolerant to such conditions. Sorghum breeding for acid soil tolerance had been conducted at PATIR-BATAN by using induced mutations with gamma irradiation. The breeding objective was to search for sorghum genotypes tolerant to acid soil condition and with regard to sorghum use for bioethanol production. A number of 66 breeding materials, including the mutants, had been screened for acid soil tolerance on land with soil pH of 4.2 and 39% Al saturation in Lampung Province. Ten sorghum genotypes had been identified as high yielding in the acid soil condition. The mutant lines GH-ZB-41-07, YT30-39-07, B-76 and B-92 had grain yield higher (>4.5 t/ha) than the control plants (Durra, Mandau and Numbu). Sorghum mutants ZH30-29-07, ZH30-30-07 and ZH30-35-07 were promising for grain-base bioethanol production with ethanol yield exceeded 2,000 l/ha. Meanwhile, the sweet sorghum mutants ZH30-35-07, ZH30-30-07 and ZH30-29-07 had brix content of 11.59, 11.95 and 10.50%, respectively. These mutant lines are promising to be developed further in sorghum breeding since they are highly tolerant to acid soils.

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The present investigation involved the assessment of heterosis for grain yield and yield attributing traits in rabi sorghum (Sorghum bicolor (L.) Moench.) hybrids by line x tester analysis. Parental material (three females and five males) was planted to undertake crossing programme following line x tester mating design and the seeds of fifteen hybrids were obtained. The experiment on line x tester was confined to fifteen hybrids with eight parents i.e. three female and five males and one check (SPV-1595) by taking ten yield contributing characters. The high heterotic effects and the highest per se performance for grain yield and its attributes were noted in the crosses Phule Anuradha x 10593 and Phule Anuradha x 10515. The hybrid M-35-1 x10593, Phule Anuradha x 10593 have high mean and high heterosis for fodder yield and other important yield parameters. Testers 10515 and 10593 and crosses Phule Anuradha x 10515, Phule Anuradha x 10538 and M-35-1 x 10593 show higherchlorophyll content. The hybrids showing high per se mean and higher heterosis may be tested at multilocations to study their stability performance for yield and yield contributing traits. [ABSTRACT FROM AUTHOR]

Stability analysis indicated that the linear component was high for leaf area per plant and dry stover yield per plant indicating that linear component contributed more towards the genotype x environment interactions, while high value of non-linear components was observed in days to maturity and plant height. In case of days to 50 per cent flowering and leaves per plant both linear and non-linear components was almost equal indicating importance of both linear and non-linear components in determining genotype x environment interactions for these attributes. For days to 50% flowering, eight male parents, 31 hybrids and check CSH 15R showed average stability over environments, whereas the female parent 104A showed above average stability and suitability to poor environments. Five male parents, 17 hybrids and check CSH 15R recorded low mean, non-significant regression coefficient and non-significant S2di values that showed average stability over environments for days to maturity. As regards to plant height 6 males and 25 hybrids were found stable and four hybrids were found above average stable and suitable for poor environments whereas, one hybrid 9168A x RSV 1006 was found below average stable for this trait. For number of leaves per plant 8 male parents and 33 hybrids showed average stability over environments and two hybrids 9168A x RSV 1006 and 9168A x SPV 1546 exhibited below average stability and suitability to favourable environments. Male SPV 1546, check BP 53 and 10 hybrids showed average stability over environments whereas the hybrid 1543A x SPV 1359 showed below average stability and suitability to favourable environments and the hybrid 1343A x RSSGV 43 exhibited above average stability and suitability for unfavourable environments for leaf area per plant. For dry stover yield per plant, ten male parents and 22 hybrids were considered stable for this trait. The hybrid 9168A x RSV 1006 showed below average stability which was suitable for rich environments. From the stability analysis, it can be concluded that none of genotype was found to be ideal with wider adaptability for all the characters, hence the parents and hybrids showing average stability for different characters could be considered for future breeding programme for genetic improvement of rabi sorghum. [ABSTRACT FROM AUTHOR]

A half diallel mating design was used to study the inheritance of anthracnose and turcicum leaf blight ( TLB) in six sorghum cultivars. Applying pathogens inoculum separately and applying both pathogens simultaneously differently affected the reaction of each genotype. GA06/18 was resistant to both pathogens. GA06/106 x Epuripuri and MUC007/009 x Epuripuri showed high heterosis for resistance to both diseases indicating that they were good materials for sorghum breeding. Additive and non-additive (dominance) variance components were almost equally reflected by equal contribution of both variances towards the anthracnose resistance suggesting that both additive and dominance gene effects were involved in anthracnose resistance. Contribution of additive gene effects towards TLB resistance was greater than non-additive gene effects suggesting that additive gene effects were more important in controlling TLB resistance. This study highlighted that deployment of resistant varieties is the most cost effective way to manage both diseases especially when integrated with appropriate agronomy practices. [ABSTRACT FROM AUTHOR]