Evaluation of bioethanol production from five different varieties of sweet and forage sorghums (Sorghum bicolor (L) Moench)

Cultivars of sweet (Rio, M81E and Della) and forage sorghums (Tato and Thor) were planted in Northeast Mexico in order to estimate optimum harvesting time, sugar production, biomass composition and ethanol yields. The juices were characterized in terms of sugar composition, free amino nitrogen (FAN) and phenolics and then yeast (Saccharomyces cerevisiae)-fermented into ethanol. The cultivars yielded different volumes of sweet juice and total sugars. They also had different optimum harvesting times. Glucose was the most abundant sugar in raw juices, followed by fructose and sucrose. FAN concentration ranged from 19 to 36 mg L⁻¹ therefore, nitrogen supplementation was required for adequate fermentation. After 18 h fermentation, there were no differences in efficiencies among cultivars but the sweet sorghums yielded more ethanol Ha⁻¹ compared to the two forage sorghums (approximately 1000 L Ha⁻¹ versus 770 L Ha⁻¹). Della was the cultivar with the highest productivity with 1051 L Ha⁻¹ ethanol produced after the first cut.     

Evaluation of drought and heat stressed grain sorghum (Sorghum bicolor) for ethanol production

Sorghum is one of the most drought-tolerant grain crops and is used in biofuel production. Since sorghum is often exposed to drought and high temperature (heat) stress, this study investigated the effect of stress applied at different phenological stages of crop development on the glucose levels in grain and subsequent ethanol production. Short season sorghum hybrid DK-28E grown under controlled environment was exposed to drought and heat stress at five different stages of growth, namely: (1) pre-flowering (boot leaf emergence) to flowering, (2) flower to seed-set, (3) seed-set to early seed-fill, (4) early seed-fill to mid seed-fill, and (5) mid seed-fill to late seed-fill stage. Drought stress at any of the growth stages did not statistically affect either the glucose content or the ethanol production compared to the control (337 mg/g), although the ethanol yield increased up to 4.5% (352 mg/g) in flowering to seed-set stage. Heat stress, on the other hand, significantly reduced the glucose release and ethanol yield compared to the control (322 mg/g). Marginal ethanol yield reduction by 9% (293 mg/g) and 8.3% (295 mg/g) was seen in plants stressed during early seed-fill to mid seed-fill and mid seed-fill to late seed-fill stages, respectively. The results suggest that the phenological stage when sorghum is exposed to stress affects the ethanol yield. Overall, from the point of ethanol yield, it appears that grain sorghum cultivated in semi-arid regions where heat and drought stress are prevalent can be used for biofuel production. However, economic viability of ethanol production, especially of grain sorghum from high temperature stress needs to be investigated.     

Water and nitrogen balance of sweet sorghum (Sorghum bicolor moench (L.)) cv. Keller under semi-arid conditions

In the framework of the E.U. project Fair CT 96-1913 “Environmental studies on sweet and fibre sorghum, sustainable crops for biomass and energy”, a research has been carried out with the aim to study the water and nitrogen balance and determine the critical N dilution curve of sweet sorghum cv. Keller. A field experiment was performed, where three irrigation treatments (I₀ = dry control, I₅₀ = 50% ETm restoration, I₁₀₀ = 100% ETm restoration) and four nitrogen fertilization levels (N₀ = no nitrogen control, N₆₀ = 60 kg ha⁻¹, N₁₂₀ = 120 kg ha⁻¹; N₁₈₀ = 180 kg ha⁻¹) were studied. The final yield was significantly affected by the amount of water distributed but not by the nitrogen level. The treatments watered up to crop establishment (I₀) produced, in the average, 7.5 t ha⁻¹ of dry matter, against 21.1 and 27.1 t ha⁻¹ of I₅₀ and I₁₀₀, respectively. The crop determined a great reduction in nitrate concentration of soil water, irrespective of nitrogen supplied. The variation between N output and input (Δ) was negative in N₀, N₆₀ and N₁₂₀ and positive in N₁₈₀. The critical value of nitrogen uptake change in relation to the water availability. The amount of nitrogen supplied did not determine significant differences upon WUE. The crop seems to have a great potentiality in Mediterranean environment in terms of yield production.     

Analysis of host plant resistance to multiple Fusarium species associated with stalk rot disease in sorghum [Sorghum bicolor (L.) Moench]

Fusarium spp. is among the largest and most important pathogen groups that attack major grain crops including sorghum. The objectives of this study were to compare the virulence of Fusarium spp. associated with sorghum and examine the mode of resistance of genotypes to the disease. Eight Fusarium species – F. verticillioides, F. thapsinum, F. andiyazi, F. proliferatum, F. nyagamai, F. pseudoanthophilum, F. brevicatenulatum, and F. pseudonygamai – were studied using three sorghum genotypes under greenhouse condition. Three of these pathogens (F. verticillioides, F. thapsinum, and F. andiyazi) were selected for genetic analysis of resistance under field conditions. Sorghum genotypes with contrasting stalk rot reactions were selected for use in both the greenhouse and field experiments. Two weeks after flowering, plants were inoculated with liquid inoculum culture (5 × 10⁴ conidia ml⁻¹) of the different pathogens. Plants were harvested 4 weeks after inoculation and rated for disease severity on the basis of lesion length and number of nodes crossed by the lesion. Among the pathogens, F. thapsinum resulted in consistently higher disease scores in all genotypes under all environments. Likewise, genotype SC599 showed the greatest and most stable resistance as inbred as well as in hybrid combinations as shown by consistently high GCA for resistance to all pathogen species. We recommend that future screening exercises for Fusarium stalk rot resistance utilize F. thapsinum as the causal organism and include the resistant genotype SC599 as a control.     

Isolation and identification of phase II enzyme inductors obtained from black Shawaya sorghum [Sorghum bicolor (L.) Moench] bran

The antioxidant capacity as oxygen radical absorbance capacity (ORAC) and in vitro chemopreventive effect of phytochemicals extracted, partitioned and isolated from the decorticated bran of black Shawaya sorghum (Sorghum bicolor L. Moench) was studied. The chemopreventive effect was evaluated as the induction effect of quinone reductase (QR) using murine hepatoma cells Hepa 1c1c7. The crude methanol extract with an antioxidant capacity of 3.7 μmol Trolox equivalent (TE)/mg was partitioned into 120 fractions with fast centrifugal partition chromatography (FCPC). Fractions with partition coefficients between 0.1 and 0.26 exerted more than 50% of the antioxidant activity of the original crude extract and contained the highest concentration of anthocyanins. No correlation was found for ferulic acid content and ORAC or chemoprevention. A derivative of 7-methoxyapigeninidin at a concentration of 1 μg/ml increased by 31% the QR activity while the original extract reached a maximum of 27% at 40 μg/ml.     

Genotype × environment interactions for shoot fly resistance in sorghum (Sorghum bicolor (L.) Moench): Response of recombinant inbred lines

Sorghum shoot fly (Atherigona soccata) is a serious pest that destabilizes the performance of sorghum cultivars and ultimately reduces sorghum production in many parts of the world. Identifying sorghum genotypes with stable resistance to shoot fly is important as it helps to reduce the cost of cultivation and stabilizes yields. In the present study, our objective was to identify stable shoot fly resistant genotypes among 385 recombinant inbred lines (RILs) of a cross between a susceptible parent and a resistant parent. We evaluated this set of RILs in eight environments over three years (2006-2008) for shoot fly resistance and component traits. Non-significant genotype-environment (G × E) linear component and significant pooled deviation for deadheart percentage indicated that the performance of genotypes was unpredictable over the environments. However, five lines had deadheart percentages much less than the population mean with regression coefficient (bi) values close to unity, and non-significant deviation from regression, indicating that they have stable shoot fly resistance and are well adapted to all the environments. Additive main effect and multiplicative interaction (AMMI) analysis partitioned main effects into genotype, environment and G × E interacts with all the components showing highly significant effects (p < 0.001). Environment had the greatest effect (69.2%) followed by G × E interactions (24.6%) and genotype (6.2%). Low heritability and high environmental influence for deadheart percentage suggested that shoot fly resistance is a highly complex character, emphasizing the need for marker assisted selection. We observed transgressive variation in the RIL population for all the traits indicating the contribution of alleles for resistance from both resistant and susceptible parents. Since the alleles for shoot fly resistance are contributed by both resistant and susceptible parents, efforts should be made to capture favourable alleles from resistant and susceptible genotypes.     

Modeling the impacts of contrasting nutrient and residue management practices on grain yield of sorghum (Sorghum bicolor (L.) Moench) in a semi-arid region of Ghana using APSIM

The cropping systems model APSIM (Agricultural Production Systems sIMulator) was applied to assess the response of sorghum grain yield to inorganic fertilizers applications and residue retention in diverse farmers’ management systems (homestead fields and bush farms). The model was parameterized using data collected from experiments under optimum growth conditions (limited water or nutrient stress). Independent data from field experiments with three levels of P and four levels of N fertilizers conducted at two different locations and soils were used to evaluate the model. Soil water and fertility parameters measured were used for simulations while same starting conditions were assumed for unmeasured parameters for all trials. APSIM predicted the grain yield response of sorghum to both N and P applications with an overall modified internal coefficient of efficiency of 0.64. Following model parameterization, a long-term simulation study was conducted using a stochastic weather data derived from historical weather data to assess the effects of crop residue management on grain production. A gradual decline in sorghum grain yield was simulated over the 30-year simulation period in both the homestead fields and the bush farms, with yields being much lower in the latter under farmers’ management practices. Half the amount of mineral N fertilizer used in the bush farms was needed in the homestead fields to produce the average grain yields produced on the bush farm with full fertilization, if crop residues were returned to the fields in the homestead. Year-to-year variability in grain yield was consistently higher with the removal of crop residues, irrespective of management systems. APSIM was responsive to both organic and inorganic fertilizer applications in the study area and also highlighted the essential role of crop residues and inorganic fertilizer in influencing the temporal sorghum grain production and hence the impact of farmers’ management practices on food security. This was evident in the rapid decline in soil organic carbon (SOC) accompanied by a decline in grain yield over the 30 years of cropping. The use of inorganic fertilizer and retention of crop residues (SOC) are critical for attaining food security in the study area.     

Double fortification of sorghum (Sorghum bicolor L. Moench) and finger millet (Eleucine coracana L. Gaertn) flours with iron and zinc

Finger millet and sorghum flours were used as vehicles for double fortification with ferrous fumarate, zinc stearate and EDTA. The iron and zinc salts were added at levels that provided 60 mg iron and 50 mg zinc per kg of flour. EDTA was added at levels equimolar to the added iron. The double-fortified finger millet and sorghum flours contained bioaccessible zinc contents of 0.83 and 1.63 mg/100 g, respectively, while the respective bioaccessible iron contents were 2.39 and 2.63 mg/100 g. The exogenous iron and zinc did not mutually interfere with their bioaccessibility. The shelf-life of the fortified flours was also satisfactory up to a period of 60 days, as indicated by the moisture and free fatty acid contents in the fortified flours. Double fortification of the millet flours did not negatively alter the sensory quality of the products prepared from them. The RDA for iron and zinc of Indian children, women and men can be sufficiently met with approximately 4 dumplings or 9 rotis. The use of such qualitatively and quantitatively rich flours can be promoted through welfare programs to reduce and subsequently eradicate iron and zinc deficiency.     

Genetic enhancement of Sorghum (Sorghum bicolor (L) Moench) for grain mould resistance: II. Breeding for grain mould resistance

Grain mould causes qualitative and quantitative loss to grain in sorghum. Grain mould resistance is a complex problem as grain mould is caused by complex of fungi and the resistance is governed by many traits. Breeding efforts during the last 3 decades to develop grain mould resistance in high yielding genotypes have not paid many dividends. We developed a strategy to breed for grain mould resistance in high yielding back ground. Twenty five crosses between elite lines and grain mould resistant genetic stocks (susceptible × resistant/moderately resistant and moderately resistant × resistant crosses) were evaluated in F₁, and derivatives performing superiorly for grain mould resistance in F₂-F₄ at physiological maturity were advanced. The early generation material F₂s (10) and F₃s (125) in 6 locations (representing rainy-season-sorghum growing 6 states of India where grain mould is one of the major biotic stresses), and later generations F₄s and F₅s in 3 locations (one location, Parbhani is a hot spot for grain moulds and 2 locations, Hyderabad and Coimbatore in epiphytotic conditions) were evaluated. Only 25 selections out of 384 derivatives in F₄ were superior over locations for grain mould resistance at physiological maturity and harvest maturity (Our simultaneous studies in RILs for grain mould resistance across years and locations have shown that the variation obtained for grain mould resistance at physiological maturity is genetically governed and the grain mould score further gets compounded at harvest maturity depending on rainfall received after physiological maturity). These superior lines were advanced and further evaluated in F₅ and F₆ for grain mould resistance and grain yield. During 2007, out of 25 F₅ derivatives, 12 were on par (scored 3.1-4.4) with resistant check, B 58586 (3.2 score) where as susceptible check, 296 B registered a score of 7.5. GMN nos. 41, 52, 59, and 63 performed on par with resistant check, B 58586 for grain mould resistance over 9 environments. Since we selected for grain mould resistance in early generations at physiological maturity in multi-locations, we could identify superior lines for grain mould resistance. Most of these lines are high yielding and on par with elite check, C43 for grain yield. These lines are distinct for DUS testing traits from grain mould resistant check, B 58586.     

Digestibility of protein and starch from sorghum (Sorghum bicolor) is linked to biochemical and structural features of grain endosperm

Although a principal source of energy and protein for millions of the world's poorest people, the nutritional value of sorghum (Sorghum bicolor L. Moench) is diminished because of low digestibility of grain protein and starch. To address this problem, we analyzed the properties of two sorghum lines that have a common pedigree but differ in digestibility. Consistent with results based on a ruminal fluid assay, the protein and starch of one line (KS48) was more thoroughly digested than that of the other (KS51) using in vitro assays based on pepsin and α-amylase. The indigestibility of KS51 relative to KS48 was shown to be due to (i) a greater abundance of disulfide-bonded proteins; (ii) presence in KS51 of non-waxy starch and the accompanying granule-bound starch synthase; and (iii) the differing nature of the protein matrix and its interaction with starch. The current findings suggest that each of these factors should be considered in efforts to enhance the nutritional value of sorghum grain.     

The effect of combined infestation by cereal aphids (Macrosiphum avenae (Fabr.) (Sitobion avenae) and Rhopalosiphum padi (L.)) and cereal leaf beetles (Oulema melanopus (L.)) on their population development and on yield of winter wheat

Previous clarification of the relationships between insect populations and damage by cereal pests has enabled the effect of combined pest infestation on the yield of winter wheat to be analysed more thoroughly. The cereal aphids Macrosiphum avenae (Fabr.) (Sitobion avenae) and Rhopalosiphum padi (L.), each in combination with the cereal leaf beetle Oulema melanopus (L.), were investigated in pot trials which enabled interactions between the combined pest populations to be studied also. Although intraspecific competition was observed for each pest population, there was no interspecific adverse effect of density on population increase. With increasing population densities of the pests in combination, the relative contribution of each species to the combined yield losses decreased. Consequently, there was no summation of individual losses, but a reduction of up to 24·3%. The ability of the cereal plant to compensate for losses may be responsible for this ‘buffering effect’, which apparently is attributable to increased dry-matter production in the presence of large combined pest populations. These results suggest that the existing economic thresholds relating to the effects of cereal aphids and cereal leaf beetle on yields of winter wheat require modification.     

The effect of ecological conditions on yield and quality traits of selected peppermint (Mentha piperita L.) clones

The commercial production of peppermint (Mentha piperita L.) depends on the genetic structure and ecological conditions affecting yield and oil composition. To determine yield and quality characters of two peppermint clones (Clone-3 and Clone-8), field experiments were carried out at four different locations (Ayd?n, Bursa, Izmir and Tokat) in Turkey during 2007 and 2008. Locations with warmer climate gave higher fresh herbage yield (Ayd?n and Izmir 37.0 t/ha and 36.8 t/ha, respectively). Although vigor canopy caused maximum fresh herbage yield, it decreased dried leaf yield due to the defoliation of leaves near to the ground. The main components menthol and menthone showed significant variation with different ecologies. Menthol contents were higher in temperate locations (Bursa and Tokat), while menthone contents were lower. The differences in oil composition of Clone-3 were lower than that of Clone-8 according to different climates, thus Clone-3 can be grown widely in various ecological conditions for oil productions as compared to the Clone-8. It was also concluded that temperate location was more suitable for peppermint oil production with high menthol contents.     

The first characterised wheat (Triticum aestivum L.) member of the nudix hydrolase family shows specificity for NAD(P)(H) and FAD

We cloned the first nudix hydrolase of wheat (Triticum aestivum L.) (TaNUDT1) and expressed it using Escherichia coli as expression host. Properties of the purified His₆-tagged protein were studied. The sequence codes for a nudix hydrolase with a molecular mass of around 43x10³ and a predicted pI of 5.68. The characteristic residues of the nudix box were highly conserved in the wheat enzyme sequence, and TaNUDT1 is most probably targeted to the peroxisomes. In the presence of dithiothreitol and MnCl₂, the enzyme hydrolyses the nicotinamide coenzymes NAD(P)(H) as could be predicted by the presence of a conserved amino acid array C-terminal to the nudix box, and the enzyme has higher affinity towards the reduced forms of the coenzymes. In light of previous reports of nudix enzymes and the physiological concentration of their substrates, we found its K_m values towards some of the coenzymes to be relatively high. As NAD(P)(H) and FAD play crucial roles in cell metabolism, extensive hydrolysis could be detrimental to cell functioning. We speculate that a decreased enzyme affinity may point to a built-in restriction on coenzyme hydrolysis in vivo. Furthermore, by hydrolysing the cofactors of several redox enzymes, this enzyme may well affect several wheat based processes.