Genome wide association analysis of acid detergent fiber content of 206 forage sorghum (Sorghum bicolor (L.) Moench) accessions

Genetic Resources and Crop Evolution - Forage sorghum (Sorghum bicolor (L.) Moench) is a C4 cereal crop with excellent quality, which is widely cultivated in many countries and regions. Acid...     

Aluminum effects on uptake and translocation of nitrogen in sorghum (Sorghum bicolor,L. Moench)

The effects of aluminum on the uptake and translocation of N in two hybrid cultivars of sorghum with differential tolerance to aluminum were studied.

Aluminum decreased the amount of N accumulated and the % of N in the aerial parts of the plants. In the roots the amount of N accumulated also decreased but the % of N increased, in both cultivars. Besides an effect on dry matter yield, Al probably reduces the uptake of N and its translocation to the aerial parts of the plant. Apparently, this impairment on N translocation resulted from Al effects on the root pressure.

Aluminum not only reduced the amount of N translocated but also changed the sap composition. The % of NO₃ ‐N decreased while the % of amino acid‐N increased suggesting an Al effect on N uptake and also on protein degradation. Asparagine and glutamine contributed about 80% of the free amino acid fraction; however, their proportions changed in presence of Al. Therefore, Al also interfered with the synthesis and/or interconversion of these amino acids.     

Genetic erosion of sorghum (Sorghum bicolor (L.) Moench) in the centre of diversity, Ethiopia

The Ethiopian region is characterised by a wide range of agro-climatic conditions, which accounted for the enormous resources of agro-biodiversity that exist in the country. The most important of these resources is the immense genetic diversity of the various crop plants in the country. Of these, one of the most on farm genetically diverse crops is sorghum. Since the advent of formal breeding in particular after green revolution, genetic diversity of most crops has been threatened worldwide. In order to assess on farm genetic erosion (GE), various research methodologies were employed. These were focused group interviews with 360 farmers, on farm monitoring and participation with 120 farmers, key informant interviews with 60 farmers and development agents, and semi-structured interviews with 250 farmers. Besides, diversity fairs were done with over 1200 farmers. Notwithstanding the complexity of assessing GE, it was assessed by various methods; namely, by temporal method (comparing 1960 and 2000 collections), area method, and semi-structured interview method at individual, community or wereda level and causes of varietal loss from other various perspectives. Farmers perceived GE as the reduced importance of the variety as indicated by lower proportion in the varietal portfolio. The five most important factors for varietal loss at individual farmers’ level were reduced benefit from the varieties, drought, Khat expansion, reduced land size and introduction of other food crops respectively. GE was not affected by wealth groups and ecological regions. Farmers do not make simple replacement as a strategic mechanism for genetic resources management. GE at regional level was quantified by temporal and spatial method. There was a complementation not rivalry between farmer varieties (FVs) and improved varieties (IVs). The whole process of GE is explained by three models, namely: Bioecogeographic enhanced genetic erosion model, Farmer induced genetic erosion model and Farmer-cum-bioecogeographic genetic erosion model. As aforementioned, sorghum genetic erosion behaviour is completely different from other food crops such as tetraploid wheat. The prediction in the late seventies that complete erosion of FVs by IVs by the end of the eighties, the principle of GE that competition between IVs and FVs, favours the former and results in the replacement of the latter is not valid in the context of sorghum in Ethiopia. Hence, maintenance of the on farm genetic diversity of sorghum is a reality but GE is rhetoric.     

Multivariate analysis of morphological variation in sorghum (Sorghum bicolor (L.) Moench) germplasm from Ethiopia and Eritrea

Multivariate methods, including principal component, cluster and discriminant analyses, were used to assess the patterns of morphological variation and to group 415 sorghum accessions for 15 quantitative characters. The first five principal components explained 79% of the total variation with plant height and days to 50% flowering being the most important characters in the first principal component. Cluster analysis grouped the accessions into ten clusters. A greater proportion of accessions of similar adaptation zones and accessions from regions of origin with similar agro-climatic conditions were grouped together. Moreover, discrimination of accessions was more pronounced when discriminant analysis was based on zone of adaptation rather than regions of origin. Based on the observed patterns of variation, it is concluded that the morphological variation in the material studied is structured by environmental factors. The implications of the results for plant breeding and germplasm conservation programmes arediscussed.     

Genetic and Phenotypic Diversity in Downy-mildew-resistant Sorghum (Sorghum bicolor (L.) Moench) Germplasm

Genetic and phenotypic diversity among randomly selected 36 downy-mildew-resistant sorghum accessions were assessed, the former using 10 simple sequence repeat (SSR) marker loci and the latter using 20 phenotypic traits. The number of alleles (a _j ) at individual loci varied from five to 14 with an average of 8.8 alleles per locus. Nei's gene diversity (H _j ) varied from 0.59 to 0.92 with an average of 0.81 per locus. High gene diversity and allelic richness were observed in races durra caudatum (H _j = 0.76, a _j = 4.3) and guinea caudatum (H _j = 0.76, a _j = 3.8) and in east Africa (H _j = 0.78, a _j = 7.2). The regions were genetically more differentiated than the races as indicated by Wright's F _st. The pattern of SSR-based clustering of accessions was more in accordance with their geographic proximity than with their racial likeness. This clustering pattern matched little with that obtained from phenotypic traits. The inter-accession genetic distance varied from 0.30 to 1.00 with an average of 0.78. Inter-accession phenotypic distance varied from 0.01 to 0.55 with an average of 0.33. Eleven accession-pairs had phenotypic distance of more than 0.50 and genetic distance of more than 0.70. These could be used as potential parents in a sorghum downy mildew resistance-breeding program.     

Amelioration of Drought in Sorghum (Sorghum bicolor L.) by Silicon

The purpose of this study was to analyze the effects of silicon (Si) nutrition on sorghum growth under drought. The present study investigated the distribution of Si in plant parts under stress conditions and its effects on physiological and growth traits. The study was conducted during 2 years (2007–2009) at PMAS Arid Agriculture University, Rawalpindi, Pakistan. Polyethylene glycol (PEG) 6000 (–4.0, –6.0, –8.0, and –10.0 Mpa) solution was used to screen drought-tolerant (Johar1) and drought-susceptible (SPV462) sorghum (Sorghum bicolor L.) cultivars, which were replicated three times with Si sources of potassium silicate (K₂SiO₃) (Si₃₀₀: 300 ml L^?1) and control (Si₀) treatments. The results showed that drought-tolerant cultivars accumulated maximum Si under Si treatment versus Si absence, which resulted increased leaf water potential, leaf area index, Soil Plant Analysis Development (SPAD) chlorophyll, net assimilation, and relative growth rate over SPV462. Similarly, Si accumulation in leaves conserved transpiration and leaf water potential, verifying Si nutrition as a defense for plants under drought.     

Sweet Sorghum [Sorghum bicolor (L.) Moench] Biomass Production for Biofuel and the Effects of Soil Types and Nitrogen Fertilization

This research aimed to determine the optimum nitrogen fertilization rate on three soils for producing biomass sweet sorghum (Sorghum bicolor cultivar M81E) and corn (Zea mays cultivar P33N58) grain yield and to compare their responses. The research was conducted in Missouri in rotations with soybean, cotton, and corn. Seven rates of nitrogen (N) were applied. Sweet sorghum dry biomass varied between 11 and 27.5 Mg ha^?1) depending on year, soil type, and N rate. Nitrogen fertilization on the silt and sandy loam soils had no effect (P > 0.05) on sweet sorghum yield grown after cotton and soybean. However, yield increased in the clay soil. Corn grain yielded from 1.3 to 12.9 Mg ha^?1, and 179 to 224 kg N ha^?1 was required for maximum yield. Increasing biomass yield required N application on clay but not on silt loam and sandy loam in rotations with soybean or cotton.     

Effects of aluminum on organic acid,sugar and amino acid composition of the root system of sorghum (Sorghum bicolor L. Moench)

The effects of aluminum on the accumulation of sugars, amino acids and organic acids in two hybrid cultivars of sorghum were studied.

The concentration of these organic compounds increased in the roots of the Al‐treated plants, mainly in the tolerant cultivar. The composition of the organic acid fraction showed a significantly higher accumulation of trans‐aconitate and malate in the tolerant cultivar as compared with the sensitive one. The higher levels of these acids in the Al‐treated plants could be interpreted as being indicative of a chelating detoxifying mechanism of aluminum in these plants.     

Genetic diversity in Sorghum bicolor(L.) Moench accessions from different ecogeographical regions in Malawi assessed with RAPDs

Genetic variation within and among several Sorghum populations from different agroecological zones in Malawi were investigated using random amplified polymorphic markers (RAPDs). DNA samples from individual plants were analyzed using 35 oligonucleotides of random sequence. Twenty five of these primers allowed amplifications of random polymorphic (RAPD) loci. Overall, 52% of the scored loci were polymorphic. Every accession was genetically distinct. The analysis of molecular variance revealed that the within-region (among accessions) variations accounted for 96.43% of the total molecular variance. Observed variations in allelic frequency was not related to agroecological differences. The degree of band sharing was used to evaluate genetic distance between accessions and to construct a phylogenetic tree. Further analysis revealed that the sorghum accessions analyzed were genetically close despite considerable phenotypic diversity within and among them. It is suggested that all the sorghum landraces currently available in Malawi should be conserved both ex situ and in situ to maintain the current level of genetic diversity.     

Changes in the diversity and geographic distribution of cultivated millet (Pennisetum glaucum (L.) R. Br.) and sorghum (Sorghum bicolor (L.) Moench) varieties in Niger between 1976 and 2003

Changes in the diversity of landraces in centres of diversity of cultivated plants need to be assessed in order to monitor and conserve agrobioversity—a key-element of sustainable agriculture. This notably applies in tropical areas where factors such as increased populations, climate change and shifts in cropping systems are hypothesized to cause varietal erosion. To assess varietal erosion of staple crops in a country subjected to various anthropogenic and natural environmental changes, we carried out a study based on a comparison of the diversity of pearl millet and sorghum varieties collected in 79 villages spanning the entire cereal-growing zone of Niger over a 26 year period (1976–2003). For these two crops, the number, name and type of varieties according to important traits for farmers were considered at different spatial scales (country, region, village) at the two collection dates. The results confirmed the high diversity of millet and sorghum varieties in Niger. No erosion of varietal diversity was noted on a national scale during the period covered. Some changes were observed but were limited to the geographical distribution of certain varieties. This highlights that farmers’ management can preserve the diversity of millet and sorghum varieties in Niger despite recurrent and severe drought periods and major social changes. It also indicates that rainfed cereal cropping systems in Niger should remain to be based on millet and sorghum, while reinforcing farmers’ seed systems.     

Effects of types of nitrogenous fertilizer (biological,chemical, integrative) and cropping mixes on some forage-medicine characteristics in additive intercropping of sorghum (Sorghum bicolor [L.] Moench) with fenugreek (Trigonella foenum-graecum L.)

In order to investigate the effects of nitrogenous fertilizers (biological, chemical, integrative) on quantity and quality of forage-medicine in the additive intercropping of sorghum with fenugreek, an experiment was performed in two agronomic years 2010–2011 and 2011–2012 in the Research Farm of Agricultural Faculty of Tehran University located in Dolatabad, Karaj, as split-plot in the form of randomized complete block design (RCBD) with three replications. The main treatments consisted of the control or without fertilizer (N0), biofertilizer (Nbi) (Azotobacter, Rhizobium, Azospirillum, mycorrhiza), chemical nitrogen fertilizer (Nch 100) and integrative fertilizer including biofertilizer plus 50% chemical nitrogen fertilizer (Nbi + Nch50). The subtreatments included sole cultivation of fenugreek without weeds (T0), sole cultivation of fenugreek with weeds (Tw), sole cultivation of sorghum without weeds (S0), sole cultivation of sorghum with weeds (Sw), cultivation of sorghum + 50% fenugreek (ST50) and cultivation of sorghum + 100% fenugreek (ST100). Based on the results, the highest effective extract of fenugreek (trigonelline) and fenugreek dry matter was gained through the application of biological fertilizer + the sole fenugreek treatment (no weeds). Moreover, the highest sorghum dry mater was yielded by the use of the integrative fertilizer + the sole sorghum (no weeds) treatment; however, the highest total dry matter was observed to be more in the mixed treatment of integrative fertilizer and sorghum + 50% fenugreek. The lowest weed biomass was also linked to the integrative treatment biological fertilizer and sorghum + 100% fenugreek.     

Interactive effects of in situ rainwater harvesting techniques and fertilizer sources on mitigation of soil moisture stress for sorghum (Sorghum bicolor (L.) Moench) in dryland areas of Tanzania

Nutrient deficiency, high rate of evapotranspiration, and insufficient and erratic rainfall are the critical challenges for crop production in the dryland areas (DLAs) of Sub-Saharan Africa, including Tanzania, where 61% of arable land is prone to drought. In addressing these challenges, field trials were conducted in central Tanzania to evaluate the interactive effects of ripping and tie-ridges with organic (FYM) and inorganic fertilizers (N) on the mitigation of the critical period of soil moisture stress (CPSMS) for sorghum yield performance. Both in situ rainwater harvesting techniques (IRWHT) and flat-cultivated land were integrated with 8 Mg FYM ha^–1, 70 Kg N ha^–1, and a combination of 35 Kg N ha^–1 and 4 Mg FYM ha^–1 (N+ FYM). Among the IRWHT, tie-ridges stored a significant water volume of 577 and 457 m³ ha^–1, which mitigated the CPSMS by the maximum of 95% and 37% for the above-average rainfall and below-average rainfall season, respectively. However, it only registered the highest grain yield (2.02 Mg ha^–1) and biomass (3.46 Mg ha^–1) in a below-average rainfall season. The highest overall grain yield (5.73 Mg ha^–) and biomass (12.09 Mg ha^–1) were harvested in ripping with combined fertilizer treatments in an above-average rainfall season, while the lowest grain yield (0.5 Mg ha^–1) and biomass (1.2 Mg ha^–1) were registered in the flat-cultivation control in the below-average rainfall season. In the latter season, IRWHT increased the mitigation potential in the order; flat cultivation < ripping < tie-ridges; and sorghum yield, highly correlated with drought mitigation index. The results showed that sorghum grain yield and final biomass performance depend on the influence of IRWHT applied, rainfall amount, soil moisture level, integrated fertilizer, and length of the CPSMS. In the above-average rainfall seasons, fertilizers mask the influence of the IRWHT. The opposite is true in the below-average rainfall season. Although ripping_– N+ FYM resulted in the highest overall yield, the study recommends practicing tie-ridges integrated with N+ FYM due to regular occurrences of low and unreliable rainfall in the dryland areas.     

Genetic variation of Ethiopian and Eritrean sorghum (Sorghum bicolor (L.) Moench) germplasm assessed by random amplified polymorphic DNA (RAPD)

The extent and patterns of distribution of genetic variation among 80 sorghum (Sorghum bicolor (L.) Moench) germplasm accessions from Ethiopia and Eritrea were investigated using RAPD with 20 oligonucleotide primers. The primers generated a total of 147 polymorphic bands across the 80 accessions with a mean of 7.35 bands per primer. Estimation of the extent of variation by the Shannon-Weaver diversity index revealed an intermediate level of overall variation (H = 53), although the levels varied among regions of origin of the accessions. Partitioning of the total variation revealed considerable variation (77%) within the region of origin of the accessions and the remainder (23%) among regions of origin. Similarly, a large portion (94%) of the total variation was found within the adaptation zones compared to among the adaptation zones (6%). The results suggest a weak differentiation of the sorghum material both on regional and agro-ecological bases, which could be ascribed to the high rate of outcrossing in cultivated sorghum and its free natural hybridization with its wild and weedy relatives, as well as to seed movement by humans. The average genetic dissimilarity was found to be 36% among the 80 accessions and 13% among the 15 regions of origin. Cluster analysis failed to group accessions of the same region or the same adaptation zone, which further confirmed the weak differentiation of the material studied. The clustering pattern of the regions of origin was broadly concordant with previous clustering patterns obtained using morphological characters, in which regions with broad agro-climatic conditions were grouped together.     

Molecular and phenotypic characterization of a collection of white grain sorghum [Sorghum bicolor (L.) Moench] for temperate climates

Genetic Resources and Crop Evolution - Sorghum [Sorghum bicolor (L.) Moench] is a subsistence crop and the main food for populations in arid or semiarid regions and it is appreciated for the...     

Effects of arbuscular mycorrhizal fungi on maize (Zea mays L.) and sorghum (Sorghum bicolor L. Moench) grown in rare earth elements of mine tailings

Rare earth elements (REE) of mine tailings have caused various ecological and environmental problems. Revegetation is one of the most cost-effective ways to overcome these problems, but it is difficult for plants to survive in polluted tailings. Arbuscular mycorrhizal fungi (AMF) can provide biotic and abiotic stress tolerance to its host plant and has widely adopted for the revegetation of degraded ecosystems. However, little is known about whether AMF plays role in facilitating the revegetation of REE of mine tailings. The objective was to investigate the uptake of nutrients and REE when plants are inoculated with AMF. A greenhouse pot experiment was conducted on the effects of Glomus mosseae and Glomus versiforme for the growth, nutritional status, and uptake of REE and heavy metals by maize (Zea mays L.) or sorghum (Sorghum bicolor L. Moench) grown in REE of mine tailings. The results indicated that symbiotic associations were successfully established between AMF and the two plant species. G. versiforme was more effective than G. mosseae at promoting plant growth by significantly increasing the uptake of nitrogen (N), phosphorus (P), and potassium (K) and decreasing carbon:nitrogen:phosphorus (C:N:P) stoichiometry. The shoot and root dry weights of the two plant species were increased by 211–387% with G. versiforme inoculation. Maize and sorghum exhibited significant differences in the REE concentrations in response to the colonization by AMF. The shoot and root lanthanum (La), cerium (Ce), praseodymium (Pr), and neodymium (Nd) concentrations of the maize inoculated with G. versiforme were decreased by approximately 70%, whereas those in the roots of sorghum were increased by approximately 70%. G. mosseae only significantly decreased the La, Ce, Pr, and Nd concentrations in the maize shoots. Inoculation with AMF also significantly decreased the concentration of certain heavy metals in the shoots and roots of maize and sorghum. These findings indicate that AMF can alleviate the effects of REE and heavy metal toxicity on plants and enhance the ability of plants to adapt to the composite adversity of REE in mine tailings.     

Ecogeographical distribution of wild, weedy and cultivated Sorghum bicolor (L.) Moench in Kenya: implications for conservation and crop-to-wild gene flow

The potential gene flow between a crop and its wild relatives is largely determined by the overlaps in their ecological and geographical distributions. Ecogeographical databases are therefore indispensable tools for the sustainable management of genetic resources. In order to expand our knowledge of Sorghum bicolor distribution in Kenya, we conducted in situ collections of wild, weedy and cultivated sorghum. Qualitative and quantitative morphological traits were measured for each sampled wild sorghum plant. Farmers’ knowledge relating to the management of sorghum varieties and autecology of wild sorghum was also obtained. Cluster analysis supports the existence of several wild sorghum morphotypes that might correspond to at least three of the five ecotypes recognized in Africa. Intermediate forms between wild and cultivated sorghum belonging to the S. bicolor ssp. drummondii are frequently found in predominantly sorghum growing areas. Crop-wild gene flow in sorghum is likely to occur in many agroecosystems of Kenya.     

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry of heteropolyflavan-3-ols and glucosylated heteropolyflavans in sorghum [Sorghum bicolor (L.) Moench

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) was used to characterize the structural diversity of polyflavans in Ruby Red sorghum [Sorghum bicolor (L.) Moench]. Deionization of the polyflavan fractions with Dowex 50 x 8-400 cation-exchange resin and subsequent addition of cesium trifluoroacetate ((133)Cs) allowed the detection of exclusively [M + Cs](+) ions. MALDI-TOF MS of the polyflavans that eluate from Sephadex LH-20 columns with methanol and acetone detected a series of masses corresponding to heteropolyflavan-3-ols differing in degree of hydroxylation and nature of the interflavan bond (A-type and B-type). MALDI-TOF MS of the Sephadex-ethanol/methanol (v/v) eluate revealed a series of masses corresponding to heteropolyflavan-5-O-beta-glucosides that vary in the extent of hydroxylation and contain a flavanone (eriodictyol or eriodictyol-5-O-beta-glucoside) as the terminal unit. The combination of liquid chromatographic separation and MALDI-TOF MS to characterize sorghum polyflavans indicates that the structural heterogeneity is much greater than previously described.     

Sorghum (Sorghum bicolor L. Moench) Flour Pasting Properties Influenced by Free Fatty Acids and Protein

A second unusually high viscosity peak appeared at the cooling stage (50°C) of a Rapid Visco‐Analyser (RVA) profile of short‐term stored (two months at room temperature) whole grain sorghum flour, while freshly ground flour had a typical pasting curve with one viscosity peak at the 95°C holding period. The formation of the second viscosity peak was caused by liberation of free fatty acids (FFA), mainly palmitic (15.6%), oleic (41.9%), and linoleic (37.9%) acids from stored flour. After the flour samples were pretreated with pepsin or the protease thermolysin, the second peak disappeared in the presence of FFA while the high viscosity was partially retained, indicating that flour protein was another essential component to the production of the actual peak. Effects of dithiothreitol (DTT), pH, and NaCl on RVA profiles of stored flour suggested that disulfide‐linked protein and electrostatic interaction are required for the peak production. In the presence of sufficient FFA, similar cooling stage viscosity peaks appeared in the RVA profiles of flour samples from maize, rice, millet, and wheat; thus, the effect was not unique to sorghum flour. Coinciding with previously reported findings from our laboratory of a three‐component interaction and discernable complex in a model system, a similar three‐component (starch, protein, and FFA) interaction was revealed in natural flour systems resulting in formation of an unusual and notably high cooling stage viscosity peak. Practical applications and an interaction mechanism are discussed.     

A flood-free period combined with early planting is required to sustain yield of pre-rice sweet sorghum (Sorghum bicolor L. Moench)

Abstract

Understanding the responses of sweet sorghum to flooding and the characters associated with flooding tolerance may be a useful strategy for pre-rice production and help meet demand for biofuel feedstock. Three sweet sorghum genotypes (Bailey, Keller and Wray) and five flooding treatments including non-flooding control, continuous flooding extended from 30, 45, 60 and 75 days after emergence to harvest were conducted under greenhouse conditions. Flooding decreased leaf dry weight (22–60%), leaf area (10–70%), number of node per stalk (1–5%), shoot dry weight (5–20%) and stalk yield (2–22%) with highest reduction in 30 days after emergence flooding treatment. Flooding later than 30 days after emergence did not significantly affect shoot growth, yield and yield components. Brix value, sucrose content and total sugar content were not significantly affected. All studied cultivars had similar shoot growth response. Flooding induced development of roots in water; root length, root dry weight, nodal root and lateral root number and interconnection of aerenchyma spaces from roots in flooded soil to stalk base above water level but suppressed root growth in flooded soil. The acclimation traits were highest in Keller, flooding from 30 days after emergence but there was a lack of root development in 75 days after emergence flooding treatments. These findings indicate the effect of waterlogging on sweet sorghum growth and yield strongly depends on the growth stage at which it occurs. There were genetic variations in root morphological and anatomical responses to flooding of sweet sorghum. The development of nodal and lateral roots and aerenchyma formation from flooded plant parts to stalk bases above water level may distribute to flooding tolerance in sweet sorghum. Based on the results, a flood-free period of at least 30 days after emergence is required to sustain yield of pre-rice sweet sorghum and early planting is highly recommended.