Differential mixing action effects on functional properties and polymeric protein size distribution of wheat dough

A micro Z-arm mixer and a 2g-Mixograph were used to compare the effect of pin and Z-arm-type mixing actions on mixing properties of wheat flour dough. Although the two mixing curves obtained with pin- and Z-arm-type mixing action showed a very similar mixing trace, no significant correlation was found between the two mixers other than the number of revolutions required for optimal dough consistency (peak resistance). Mixing requirement was described by a rate-independent parameter, the number of revolutions to peak dough development and was found to be greater in a Z-arm mixer than in a pin mixer. Mixing requirement showed significant correlation with stability, which is therefore a dough strength parameter. The change in the polymeric structure of gluten proteins of dough as indicated by %UPP (unextractable polymeric protein percentage) was monitored and showed a smaller decrease with Z-arm mixing than with pin mixing. Therefore, pin-mixing action is more energetic than Z-arm mixing. At peak resistance, Z-arm mixing gives a larger quantity of polymeric protein content in the dough relative to pin mixing. The degree of dough development at maximum resistance in the different mixers was shown to be different. A new parameter, delta-_UPPMZ${\mathrm{UPP}}_{\mathrm{MZ}}$ (the difference between %UPP of dough obtained with pin vs Z-arm mixing actions) was identified and proposed to have some relationship to the stability of the polymeric proteins in the dough.     

Contribution of common wheat protein fractions to dough properties and quality of northern-style Chinese steamed bread

Thirty-three cultivars and advanced lines originated from China, Mexico, and Australia were sown in four environments in Chinese spring wheat regions to investigate the association between gluten protein fractions determined by reversed-phase high-performance liquid chromatography (RP-HPLC), and dough properties and northern-style Chinese steamed bread (CSB) quality. The genotypes were divided into two groups of 10 and 23 entries with and without the 1B/1R translocation, respectively. 1B/1R translocation lines had significantly high amounts of ω  -gliadins, and low levels of glutenin and low molecular weight glutenin subunits (LMW-GS), but no significant difference in dough properties and CSB quality from non-translocation lines. The association between protein fractions and dough properties, and CSB quality largely depended upon the presence of 1B/1R translocation. Gliadin contributed more in quantity to flour protein content (FPC) than glutenin, while glutenin and its fractions contributed more to dough strength and CSB quality. Among non-translocation lines, moderate to high correlation coefficients between quantified glutenin and its fractions, and farinograph development time (DT, r=0.85$r=0.85$–0.92) and stability (ST, r=0.81$r=0.81$–0.93), extensograph maximum resistance (R_max, r=0.90$r=0.90$–0.93), CSB stress relaxation (SR, r=0.55$r=0.55$–0.61) and CSB score (r=0.56$r=0.56$–0.62), were observed. Gliadin:glutenin ratios showed significant and negative associations with dough properties and CSB quality. Correlation coefficients between gliadin:glutenin, gliadin:HMW-GS, gliadin:LMW-GS ratios, and CSB score were −0.79, −0.73, and −0.79 among non-translocation lines, respectively. HMW-GS and LMW-GS, x-type HMW-GS and y-type HMW-GS contributed similarly to dough properties and CSB quality for non-translocation lines. Weak correlations between protein fractions and dough properties, and CSB quality were observed among translocation lines. This information should be useful for improvement of dough properties and CSB quality.     

Heat stress effects around flowering on kernel set of temperate and tropical maize hybrids

Final kernel number in the uppermost ear of temperate maize (Zea mays L.) hybrids is smaller than the potential represented by the number of florets differentiated in this ear, and than the number of silks exposed from it (i.e., kernel set <1). This trend increases when stressful conditions affect plant growth immediately before (GS₁) or during (GS₂) silking, but the magnitude of change has not been documented for heat stress effects and hybrids of tropical background. In this work we evaluated mentioned traits in field experiments (Exp₁ and Exp₂), including (i) two temperature regimes, control and heated during daytime hours (ca. 33-40 °C at ear level), (ii) two 15-d periods during GS₁ and GS₂, and (iii) three hybrids (Te: temperate; Tr: tropical; TeTr: Te × Tr). We also measured crop anthesis and silking dynamics, silk exposure of individual plants, and the anthesis-silking interval (ASI). Three sources of kernel loss were identified: decreased floret differentiation, pollination failure, and kernel abortion. Heating affected all surveyed traits, but negative effects on flowering dynamics were larger (i) for anthesis than for silking with the concomitant decrease in ASI, and (ii) for GS₁ than for GS₂. Heat also caused a decrease in the number of (i) florets only when performed during GS₁ (−15.5% in Exp₁ and −9.1% in Exp₂), and only among Te and TeTr hybrids, (ii) exposed silks of all GS × Hybrid combinations, and (iii) harvestable kernels (mean of −51.8% in GS₁ and −74.5% in GS₂). Kernel abortion explained 95% of the variation in final kernel numbers (P < 0.001), and negative heat effects were larger on this loss (38.6%) than on other losses (≤11.3%). The tropical genetic background conferred an enhanced capacity for enduring most negative effects of heating.     

Effects of temperature and photoperiod on flowering time of forage legumes in a Mediterranean environment

Flowering time plasticity is a commonly occurring adaptive characteristic of fodder crops, including legumes, in arid and semiarid environments of the Mediterranean regions. Time of flowering is mainly influenced by genotype, temperature and photoperiod. Field experiments were carried out at Foggia (southern Italy) during successive growing seasons (from 8 to 16 growing cycles according to species) to study the relation among air temperature, photoperiod and duration of the morphological development of flowering in eight forage legume species: sulla (Hedysarum coronarium L.), sainfoin (Onobrychis viciifolia Scop.), pea (Pisum sativun L.), berseem clover (Trifolium alexandrinum L.), Persian clover (Trifolium resupinatum L.), faba bean (Vicia faba L.), common vetch (Vicia sativa L.) and hairy vetch (Vicia villosa Roth). Time to reach 10% flowering (EF) and 100% flowering (FF) were recorded. Rate of progress to flowering, defined as the inverse of time from sowing to EF and FF, was related to mean daily temperature, or to both mean daily temperature and mean photoperiod. Using the linear equations, the thermal time requirements (T_t) and the base temperature (T_b) expressed as heat units were determined by the x-intercept method for both EF and FF stages. Evaluation of flowering time was also based on days after planting (DAP), day of year (DOY) and on a photothermal index (PTI). For all species, a significant negative correlation (P ≥ 0.01) was found between planting date (PD) and DAP whereas PTI showed a significant negative relationship (P ≥ 0.05) only for faba bean, pea, berseem clover and common vetch. In sainfoin, sulla and berseem clover, the rate of progress to flowering was affected significantly (P ≥ 0.05) by both mean temperature and photoperiod. The T_t requirements to reach the EF and the FF stage ranged from 871 to 1665 °C day and from 1043 to 1616 °C day, respectively, for the studied species. Both phenological stages considered depended upon accumulated thermal time above a species-specific base temperature. Furthermore, in all legumes the onset of flowering only occurred when dual thresholds of a minimum T_t and a minimum photoperiod were reached, which were specific to each species.     

Chemical Composition,Antifeedant, Repellent,and Toxicity Activities of the Rhizomes of Galangal,Alpinia galanga Against Asian Subterranean Termites,Coptotermes gestroi and Coptotermes curvignathus (Isoptera: Rhinotermitidae)

Dual choice bioassays were used to evaluate the antifeedant property of essential oil and methanolic extract of Alpinia galanga (L.) (locally known as lengkuas) against two species of termites, Coptotermes gestroi (Wasmann) and Coptotermes curvignathus (Holmgren) (Isoptera: Rhinotermitidae). A 4-cm-diameter paper disc treated with A. galanga essential oil and another treated with either methanol or hexane as control were placed in a petri dish with 10 termites. Mean consumption of paper discs (miligram) treated with 2,000 ppm of essential oil by C. gestroi was 3.30 ± 0.24 mg and by C. curvignathus was 3.32 ± 0.24 mg. A. galanga essential oil showed significant difference in antifeedant effect, 2,000 ppm of A. galanga essential oil was considered to be the optimum concentration that gave maximum antifeedant effect. The essential oil composition was determined using gas chromatography-mass spectrometry. The major component of the essential oil was 1,8-cineol (61.9%). Antifeedant bioassay using 500 ppm of 1,8-cineol showed significant reduction in paper consumption by both termite species. Thus, the bioactive agent in A. galangal essential oil causing antifeeding activity was identified as 1,8-cineol. Repellent activity shows that 250 ppm of 1,8-cineol caused 50.00 ± 4.47% repellency for C. gestroi, whereas for C. curvignathus 750 ppm of 1,8-cineol was needed to cause similar repellent activity (56.67 ± 3.33%). C. curvignathus is more susceptible compare to C. gestroi in Contact Toxicity study, the lethal dose (LD₅₀) of C. curvignathus was 945 mg/kg, whereas LD₅₀ value for C. gestroi was 1,102 mg/kg. Hence 1,8-cineol may be developed as an alternative control against termite in sustainable agriculture practices.     

Identification and Expression of Two Novel Cytochrome P450 Genes,CYP6CV1 and CYP9A38, in Cnaphalocrocis medinalis (Lepidoptera: Pyralidae)

Cnaphalocrocis medinalis Güenée can cause severe losses in rice. Cytochrome P450s play crucial roles in the metabolism of allelochemicals in herbivorous insects. Two novel P450 cDNAs, CYP6CV1 and CYP9A38, were cloned from the midgut of C. medinalis. CYP6CV1 encodes a protein of 500 amino acid residues, while CYP9A38-predicted protein has 531 amino acid residues. Both cDNA-predicted proteins contain the conserved functional domains for all P450s. Phylogenetic analyses showed that CYP6CV1 is grouped in the cluster containing CYP6B members, while CYP9A38 is in the cluster including CYP9 members. However, both clusters are contained in the same higher lineage. Homologous analysis revealed that CYP6CV1 is most similar to CYP6B8, CYP6B7, CYP6B6, CYP6B2, and CYP6B4 with the highest amino acid identity of 41%. CYP9A38 is closest to CYP9A17, CYP9A21, CYP9A20, and CYP9A19 with the highest amino acid identity of 66%. Studies of temporal expression profiles revealed that CYP9A38 showed a steady increase in mRNA level during the five instar stages, but a low-expression level in pupae, and then presented at a high-expression level again in adults. Similar expression patterns were obtained with CYP6CV1. In the fifth instar larvae, CYP6CV1 was mainly expressed in midgut and fat bodies, whereas CYP9A38 was mainly expressed in midgut. Expression studies also revealed a 3.20-fold over-expression of CYP6CV1 and 3.54-fold over-expression of CYP9A38 after larval exposure to host rice resistance. Our results suggest that both CYP6CV1 and CYP9A38 may be involved in detoxification of rice phytochemicals.     

Influence of grain quality,heat, and processing time on the reduction of aflatoxin B1 levels in ‘tuwo’ and ‘ogi’: Two cereal-based products

During the production of tuwo from laboratory-contaminated corn (AFB₁:150 mcg/kg) and sorghum (AFB₁:87.5 mcg/kg) grains, reductions in the aflatoxin-B₁ levels of pastes boiled for 30 min and 60 min were found to be 68.0% and 80.8%, respectively. In the preparation of ogi from contaminated corn and sorghum grains, reductions of about 72.5% and 71.4%, respectively, were obtained after fermentation at ambient conditions. Reconstitution of ogi paste into a porridge (akamu) considerably reduced the AFB level.     

Evaluation of antioxidant activities of the edible and medicinal Suaeda species and related phenolic compounds

Antioxidants are the chemical substances that reduce or prevent oxidation. The present study aimed to assess in vitro and ex vivo antioxidant activities of four acetonic extracts Tunisian halophytes (Suaeda fruticosa, Suaeda pruinosa, Suaeda mollis and Suaeda maritima). Various experimental models were used for characterization of antioxidant activities of shoot extracts. Eventually, the promising specie was subjected to phenolic identification using RP-HPLC. The analyzed shoot extracts exhibited that antioxidant activities varied considerably as function of species. The highest DPPH scavenging ability was found in S. mollis with the lowest IC₅₀ value (2.5 μg/ml), followed by S. pruinosa, S. fruticosa and S. maritima. The same tendency was observed with ferric reducing power. Concerning β-carotene bleaching assays and total antioxidant activity, results showed that S. fruticosa exhibited the highest antioxidant ability against the inhibition of β-carotene bleaching, and a better total antioxidant capacity. Moreover antioxidant capacities using ORAC method and a cell based-assay showed that S. mollis, S. fruticosa, and S. pruinosa exhibit statistically similar antioxidant activity. The identification of phenolic compounds in S. mollis extract using RP-HPLC revealed that 2,5-dihydroxybenzoic acid and rutin hydrate were the major molecules. These results suggested that Suaeda species showed a variability of their antioxidant activities.     

Effects of storage on the physico-chemical properties of corn tortillas prepared with glycerol and salt

Corn tortillas have a short shelf life due to increased firmness and microbial spoilage. Commercial corn tortillas use carboxymethyl cellulose (CMC) to delay staling; however this gum is expensive when compared to the rest of the tortilla ingredients. Glycerol has been added to bread and wheat tortillas to increase pliability and salt has been shown to mask the flavor of glycerol in corn tortillas. The possibility to reduce staling in corn tortillas by adding glycerol/salt as an alternative to CMC was investigated by monitoring changes in physico-chemical properties during 2 weeks of storage at 25 °C. Molecular and macroscopic changes were followed using thermal and mechanical analysis. During storage an increase in amylopectin recrystallization was observed in all samples. The “freezable” water content of all tortillas decreased over the first 3–5 days of storage with an increase after 7 days, while moisture content and water activity remained constant. Glycerol/salt tortillas exhibited a sharper transition region in the DMA temperature scan suggesting a more homogenous sample. CMC tortillas were significantly stiffer than glycerol tortillas after 14 days of storage. Glycerol/salt combinations may offer at least a partial replacement for CMC since it helped control the stiffness, water homogeneity and distribution during storage.     

Biochemistry of Fruit Ripening of Guava (Psidium guajava L.): Compositional and Enzymatic Changes

Changes in chemical composition and the activities of hydrolytic enzymes during four different stages of maturity, viz. mature green (MG), color turning (CT), ripe (R), and overripe (OR), have been studied in guava fruits cv. Banarsi Surkha. Chlorophyll content decreased while carotenoid content increased during ripening. Starch content decreased with concomitant increase in alcohol-soluble sugars. Cellulose, hemicellulose, and lignin also decreased up to ripe stage, while pectin continued to decrease up to OR stage. PG (polygalacturonase) and cellulase exhibited progressive increase in activity throughout ripening, whereas pectin methyl esterase (PME) activity increased up to CT stage and decreased at R stage. The activities of alpha-amylase and beta-amylase decreased significantly with ripening. The most notable metabolic changes occurred between MG and CT stage, implying that for improved postharvest handling, guava fruits may be harvested at CT stage.     

Efficient genetic transformation of Jatropha curcas L. by microprojectile bombardment using embryo axes

An efficient and reproducible protocol was established for genetic transformation in Jatropha curcas through microprojectile bombardment. Decotyledonated embryos from mature seeds were pre-cultured for 5 days and elongated embryonic axis was subjected to bombardment for the optimization of physical parameters. The frequency of transient gus expression and survival of putative transformants were taken into consideration for the assessment of physical parameters. Statistical analysis reveal that microcarrier size, helium pressure and target distance had significant influence on transformation efficiency. Among different variables evaluated, microcarrier size 1 μm, He pressure 1100 and 1350 psi with a target distance of 9 and 12 cm respectively were found optimum by co-relating microcarrier size, helium pressure and target distance on the frequency of gus expression and survival of putative transformants. Selection of putative transformants was done with increasing concentrations (5-7 mg L⁻¹) of hygromycin. The integration of desired gene into Jatropha genome was confirmed with PCR amplification of 0.96 and 1.28 kb bands of hptII and gus gene respectively from the T₀ transgenics and Southern blot analysis using PCR amplified DIG labeled hptII gene as a probe. A successful attempt of genetic transformation was made with optimized conditions using particle gene gun and establishing a stable transformation in J. curcas with 44.7% transformation efficiency. The procedure described will be very useful for the introgression of desired genes into J. curcas and the molecular analysis of gene function.     

Complex Toxin Profile of French Mediterranean Ostreopsis cf. ovata Strains,Seafood Accumulation and Ovatoxins Prepurification

Ostreopsis cf. ovata produces palytoxin analogues including ovatoxins (OVTXs) and a putative palytoxin (p-PLTX), which can accumulate in marine organisms and may possibly lead to food intoxication. However, purified ovatoxins are not widely available and their toxicities are still unknown. The aim of this study was to improve understanding of the ecophysiology of Ostreopsis cf. ovata and its toxin production as well as to optimize the purification process for ovatoxin. During Ostreopsis blooms in 2011 and 2012 in Villefranche-sur-Mer (France, NW Mediterranean Sea), microalgae epiphytic cells and marine organisms were collected and analyzed both by LC-MS/MS and hemolysis assay. Results obtained with these two methods were comparable, suggesting ovatoxins have hemolytic properties. An average of 223 μg·kg⁻¹ of palytoxin equivalent of whole flesh was found, thus exceeding the threshold of 30 μg·kg⁻¹ in shellfish recommended by the European Food Safety Authority (EFSA). Ostreopsis cells showed the same toxin profile both in situ and in laboratory culture, with ovatoxin-a (OVTX-a) being the most abundant analogue (~50%), followed by OVTX-b (~15%), p-PLTX (12%), OVTX-d (8%), OVTX-c (5%) and OVTX-e (4%). Ostreopsis cf. ovata produced up to 2 g of biomass per L of culture, with a maximum concentration of 300 pg PLTX equivalent cell⁻¹. Thus, an approximate amount of 10 mg of PLTX-group toxins may be produced with 10 L of this strain. Toxin extracts obtained from collected biomass were purified using different techniques such as liquid-liquid partition or size exclusion. Among these methods, open-column chromatography with Sephadex LH20 phase yielded the best results with a cleanup efficiency of 93% and recovery of about 85%, representing an increase of toxin percentage by 13 fold. Hence, this purification step should be incorporated into future isolation exercises.     

The use ofEscherichia coli mutants to measure the bioavailability of essential amino acids in foods

The -galactosidase-based assay for lysine developed by Tuffnell & Payne was used to measure the bioavailabilities of cyst(e)ine, methionine, threonine and tryptophan in pronase digests of 17 foods. The digests were assayed by estimating the -galactosidase synthesis responses of fiveEscherichia coli mutants, each requiring one of the respective amino acids for protein synthesis. Deletion mutants were used whenever possible in order to ensure strain stability. Single digests of each food were assayed with 3 or 4 separate cultures of each mutant and the results were compared with those from the corresponding chemical assay. Omitting the anomalously low values for one food, the rank correlation coefficients of the bio- and chemo-assay values were 0.61 (cysteine), 0.91 (lysine), 0.95 (methionine), 0.64 (threonine) and 0.85 (tryptophan). Mean (± S.D.) relative amino acid bioavailabilities (casein = 100%) for the 17 foods were: cysteine, 53±23; lysine, 90±10; methionine, 95±18; threonine, 89±13; and tryptophan, 89±25. The cysteine mutant appeared to give unusually low bioavailability values except for the milk products. These amino acid mutants afford a rapid method for assaying the bioavailabilities of at least four of the five amino acids studied.     

The Glycolytic Enzymes Activity in the Midgut of Diabrotica virgifera virgifera (Coleoptera: Chrysomelidae) adult and their Seasonal Changes

The western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae) is an important pest of maize. The diet of the D. virgifera imago is rich in starch and other polysaccharides present in cereals such as maize. Therefore, knowledge about enzymes involved in digestion of such specific food of this pest seems to be important. The paper shows, for the first time, the activities of main glycolytic enzymes in the midgut of D. virgifera imago: endoglycosidases (α-amylase, cellulase, chitinase, licheninase, laminarinase); exoglycosidases (α- and β-glucosidases, α- and β-galactosidases) and disaccharidases (maltase, isomaltase, sucrase, trehalase, lactase, and cellobiase). Activities of α-amylase, α-glucosidase, and maltase were the highest among assayed endoglycosidases, exoglycosidases, and disaccharidases, respectively. This indicates that in the midgut of D. virgifera imago α-amylase, α-glucosidase and maltase are important enzymes in starch hydrolysis and products of its digestion. These results lead to conclusion that inhibition of most active glycolytic enzymes of D. virgifera imago may be another promising method for chemical control of this pest of maize.     

Gibberellic acid (GA3) induced changes in proanthocyanidins and malt quality of two and six-row husked barleys

Analysis of husked barleys for proanthocyanidins and malt qualityattributes has shown that not a single variety is free ofproanthocyanidins. The proanthocyanidins in barley grains variedfrom 3.85 to 4.94 mg/g as catechin equivalent. The concentrationof proanthocyanidins decreased, while total soluble sugars, reducingsugars, diastatic power and -amylase activity increasedduring maltings as well as with exogenous gibberellic acid (GA₃)application. Alfa 93 (two-row) and RD2560 (six-row) varietiesappeared to be superior for malting and brewing purposes on thebasis of proanthocyanidins, total phenols, diastatic power and-amylase activity. It is suggested that exogenous applicationof GA₃ at 15 ppm may be useful for producing good quality maltfrom barley grains.     

Valorisation of Jatropha curcas: Solubilisation of proteins and sugars from the NaOH extracted de-oiled press cake

In this study, we investigated the possibilities for increasing the valorisation of de-oiled Jatropha press cake (DO-JPC). The studied raw material is the by-product of the alkaline protein extraction of the DO-JPC: NaOH Extracted DO-JPC (NEDO-JPC). Protein solubilisation of NEDO-JPC was performed under neutral and acidic conditions (pH 2, 100 mM maleic acid), at elevated temperature (100, 120, and 140 °C), and at 5% (w/w) dry solids loading. After the treatment, the amount of solubilised protein was determined, as well as the solubilisation of polymeric sugars and formation of sugar degradation products furfural and 5-hydroxymethylfurfural (HMF). Although a clear influence is shown for temperature, no difference in protein solubilisation was found between treatments at pH 7 and pH 2. A maximum of 25% (w/w) of the available protein was solubilised, at 140 °C. The lignocellulose fraction of NEDO-JPC proved relatively recalcitrant to acid hydrolysis, suggesting a more intense treatment to be necessary to sufficiently increase accessibility for cellulolytic enzymes in a lignocellulosic bioethanol process. At €8.00 per tonne DO-JPC, it is concluded that the possibilities for valorisation of the protein fraction of NEDO-JPC at neutral and acid pH are limited, leaving the lignocellulose fraction as a source of valorisation to be investigated.     

A Collaborative Evaluation of LC-MS/MS Based Methods for BMAA Analysis: Soluble Bound BMAA Found to Be an Important Fraction

Exposure to β-N-methylamino-l-alanine (BMAA) might be linked to the incidence of amyotrophic lateral sclerosis, Alzheimer’s disease and Parkinson’s disease. Analytical chemistry plays a crucial role in determining human BMAA exposure and the associated health risk, but the performance of various analytical methods currently employed is rarely compared. A CYANOCOST initiated workshop was organized aimed at training scientists in BMAA analysis, creating mutual understanding and paving the way towards interlaboratory comparison exercises. During this workshop, we tested different methods (extraction followed by derivatization and liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) analysis, or directly followed by LC-MS/MS analysis) for trueness and intermediate precision. We adapted three workup methods for the underivatized analysis of animal, brain and cyanobacterial samples. Based on recovery of the internal standard D₃BMAA, the underivatized methods were accurate (mean recovery 80%) and precise (mean relative standard deviation 10%), except for the cyanobacterium Leptolyngbya. However, total BMAA concentrations in the positive controls (cycad seeds) showed higher variation (relative standard deviation 21%–32%), implying that D₃BMAA was not a good indicator for the release of BMAA from bound forms. Significant losses occurred during workup for the derivatized method, resulting in low recovery (<10%). Most BMAA was found in a trichloroacetic acid soluble, bound form and we recommend including this fraction during analysis.     

Foliar application of chitosan activates artemisinin biosynthesis in Artemisia annua L.

There has been much interest in artemisinin owing to its excellent activity against malaria, an infectious disease threatening the tropical world. However, the low artemisinin content (0.01-0.8%, DW) in Artemisia annua, which is the only commercial source of artemisinin, makes artemisinin expensive to produce and not yet available on a global scale. Here we show that foliar application of 100 mg l⁻¹ chitosan improved artemisinin biosynthesis in A. annua. The content of dihydroartemisinic acid and artemisinin in chitosan-treated leaves increased by 72% and 53% compared with control values, respectively. Chitosan induced the expression of ADS and DBR2, which could explain the increase in level of artemisinic metabolites. After chitosan treatment, the amounts of hydrogen peroxide (H₂O₂) and superoxide anion (O₂⁻) in leaves of A. annua were 1.4 and 3.0 times higher than those of the control, respectively. Accumulation of reactive oxygen species (ROS) probably accelerated the conversion of dihydroartemisinic acid to artemisinin. Foliar application of 100 mg l⁻¹ chitosan had no harmful effect on A. annua growth. The simple method described here could be an effective method to improve artemisinin production in A. annua field cultivation.     

Modeling nutrient and water productivity of sorghum in smallholder farming systems in a semi-arid region of Ghana

The CERES-sorghum module of the Decision Support System for Agro-Technological Transfer (DSSAT) model was calibrated for sorghum (Sorghum bicolor (L.) Moench) using data from sorghum grown with adequate water and nitrogen and evaluated with data from several N rates trials in Navrongo, Ghana with an overall modified internal efficiency of 0.63. The use of mineral N fertilizer was found to be profitable with economically optimal rates of 40 and 80 kg N ha⁻¹ for more intensively managed homestead fields and less intensively managed bush fields respectively. Agronomic N use efficiency varied from 21 to 37 kg grain kg⁻¹ N for the homestead fields and from 15 to 49 kg grain kg⁻¹ N in the bush fields. Simulated grain yield for homestead fields at 40 kg N ha⁻¹ application was equal to yield for bush fields at 80 kg N ha⁻¹. Water use efficiency generally increased with increased mineral N rate and was greater for the homestead fields compared with the bush fields. Grain yield per unit of cumulative evapo-transpiration (simulated) was consistently higher compared with yield per unit of cumulative precipitation for the season, probably because of runoff and deep percolation. In the simulation experiment, grain yield variability was less with mineral N application and under higher soil fertility (organic matter) condition. Application of mineral N reduced variability in yield from a CV of 37 to 11% in the bush farm and from 17 to 7% in the homestead fields. The use of mineral fertilizer and encouraging practices that retain organic matter to the soil provide a more sustainable system for ensuring crop production and hence food security.     

Changes Caused by Genotype and Environmental Conditions in Beta-Glucan Content of Spring Barley for Dietetically Beneficial Human Nutrition

Over the 5-year period (2000-2004), a significantly higher beta-glucan content was detected in the waxy varieties Washonubet, Wabet, and Wanubet (6.8-7.6%) and lines formed by crossing these varieties with malting varieties (5.8-7.1%). Conversely, the non-waxy hulled malting-type varieties Kompakt (4.0%) and Krona (4.3%) had significantly lower contents of beta-glucan. The observations also showed that concentrations of beta-glucans in 2000-2004 were significantly affected not only by varieties, but also environmental conditions in the growing periods and interactions of these two factors. Higher precipitation during the flowering time and grain filling period and lower temperatures during the flowering time in 2002 had negative effects on concentration of beta-glucans. Conversely, drier and warmer weather in 2003 enhanced the content of beta-glucans. The results show that it is possible to increase the content of beta-glucan in spring barley grain by implementing selective breeding practices. Compared to the parental malting varieties, the mean content of beta-glucans in F(4)-F(8) generations was increased by 1.8 and 2.0% by recombination in lines Kompakt x Wabet and Wanubet x Krona, respectively. Significant effect of environmental conditions and their interactions with varieties indicated the necessity to assess standard qualities of barley as a food material.