The response to <Emphasis Type="Italic">Potato virus X</Emphasis> infection of tomato plants treated with ISR2000

Elsinoë fawcettii, a fungal pathogen causing scab disease in citrus, is one of the destructive diseases having an adverse role in the fresh fruit market. We observed the infection behaviour of E. fawcettii on young leaves of satsuma mandarin daily and described the time course of symptom development with a focus on morphological changes during disease progress. The E. fawcettii isolate 16–1, belonging to Florida Broad Host Range (FBHR), was infectious and generated typical symptoms on adaxial as well as abaxial surfaces of the leaf. Of the conidia inoculated and adhered, only a few were able to germinate and create typical symptoms. Conidia extended their germ tubes from 1 day post-inoculation where a few possessed globose appressorium-like structures (APL) at their tip. The APL were found on both surfaces while symptoms could be produced without them. Dark regions were induced 1–2 days post-inoculation (dpi) under fluorescent microscopic observation. Cuticle and mesophyll cells including epidermis in the infected dark region were degraded, resulting in cellular necrosis. The adjacent cells of the necrotic region were enlarged and gradually covered leaving a grooved shaped necrotic center and appeared as a first visible symptom 3 dpi. Hyphae were extended through the necrotic epidermis and colonized intra- and inter-cellularly in mesophyll tissue. Also lamellated cell-wall was observed as a boundary between infected and non-infected regions in the lesion after typical symptoms were formed. The lamellation in the cell simultaneously occurred forming a compaction of host cells and a semi-circular arc of lammellated cells was formed on the boundary of the infected and non-infected regions of the lesion.     

Characterization and Leachability Propensity of Bottom Ash from Medical Waste Incineration

The leachability of bottom medical waste ash from a Jordanian incinerator was studied in this work. The ash was characterized in terms of particle size distribution, chemical and mineralogical composition followed by leaching of several size fractions at different conditions (leaching time, temperature, initial pH, particle size, and solid liquid ratio). The major elements found in the ash were Ca, Si, Al, Cl, Na, Fe, Ti, S, Mg, Ba, and K, while the main mineral phases found in the ash were calcite, halite, sylvite, anhydrite, hematite, hydrochlorborite, cristobalite, melanterite, and chlormayenite. Leaching data indicates that as leaching time and S/L increased, the concentration of metals increased in the leachate. The highest leaching level was at a S/L ratio of 60 mg/ml. As the particles sizes decreased, the concentration of the majority of metals studied increased. Meanwhile, the effect of particle size on other metals was not regular due to the fact that sieving resulted in more concentrated metals in certain particle size fractions. Leachability results also indicate that variation in the initial pH has a slight effect on the degree of leaching. The concentration of some metal ions increased with temperature, while others increased initially but subsequently decreased. The extracted quantities of all the heavy metals were less than the limits set by EPA.     

Treatment of Cotton Fiber with Newly Synthesized UV Absorbers: Optimization and Protection Efficiency

Two new hetrofunctional triazine based UV absorbers (1a, 2a) were theoretically and experimentally synthesized at our previous work. In the current investigation, these absorbers were applied to woven cotton fabric via the exhaust method of dyeing, that increase the ultraviolet protection factor of fabric by keeping the quantity of finishing chemicals low to combat with the environmental problem. Therefore, a statistical tool central composite rotatable design (CCRD) of response surface methodology (RSM) was selected for process modeling. The CCRD was applied to study the effect of three process variables (salt, alkali and temperature) on the two responses (exhaustion and fixation percentage) and for the evaluation of the interactive effects of the three process variables. The results show that the applied quadratic model was highly significant and fit to the experimental data for both the UV absorbers (1a and 2a). The values of optimized parameters for CCRD, in cotton finishing with newly synthesized UV absorbers (1a and 2a) were respectively as follows; temperature of 61.91 oC, dose of salt 34.28 g/l and dose of alkali 19.82 g/l. Under these conditions, 77.56 (±3) and 76.08 (±3) exhaustion and 81.12 (±3) and 79.23 (±3) fixation percentage obtained for UV absorbers 1a and 2a respectively. The ultraviolet protection factor (UPF) of treated cotton fabric under optimized conditions appeared in very good range. The results reveal that the applied statistical design economically and effectively predicts the optimized conditions of finishing of cotton by keeping the number of experiments low than the one factor at a time method, that ultimately reduce water pollution and wastage of resources.     

Genotype by environment interaction of seed and oil yield in vernonia (Vernonia galamensis variety ethiopica)

Vernonia (Vernonia galamensis variety ethiopica) is a potentially novel renewable source of natural epoxy oil. The objective of this study was to determine the genotype by environment interaction and to identify superior and stable genotypes of vernonia with high seed and oil yield. Field experiments were conducted during 2006, 2007 and 2008 at two localities namely, Gabaza and Syferkuil. Ten selected genotypes of vernonia were evaluated for seed yield, oil content and oil yield using the randomized complete block design with three replications. Significant interactions (P ≤ 0.05) were detected among genotype by location for seed yield, oil content, oil yield and genotype by year for seed and oil yield. Genotype Vge-18 had the highest seed yield ranging between 3095 and 3337 kg/ha followed by Vge-17 yielding 3006-3137 kg/ha at Gabaza. These genotypes were also the best performers at Syferkuil where Vge-17 yielded 2915-3217 kg/ha followed by Vge-18 with 2819-3152 kg/ha. The superiority statistics allocated Vge-17 and Vge-18 as best yielding and stable genotypes. In both locations Vge-4 had increased seed oil contents at 43% (Gabaza) and 35% (Syferkuil). Other promising genotypes with high seed oil content were Vge-33 at Gabaza (40-43%) and Vge-3 at Syferkuil (34-35%). Genotypes with the highest oil yields were found to be Vge-18 (1117-1370 kg/ha) at Gabaza and Vge-4 with yields of 885-922 kg/ha at Syferkuil. Overall, Vge-17 and Vge-18 were identified as having the highest seed yield, while Vge-4 and Vge-3 yielded the highest seed oil content with average stability. These genotypes could be used for direct large scale production or strategic breeding of vernonia in these or similar environments.     

Quantitative trait loci of acid detergent fiber and grain chemical composition in hulled × hull-less barley population

Cultivated barley is the major livestock feed grain in the Northern Plains and Northwestern United States due to the fact that its short growing season and limited rainfall limit the planting and production of corn. Starch and fiber content play a significant role in feedlot performance of animals raised on barley feed. To study the underlying genetic locations and mechanisms for these traits, a recombinant inbred line population was derived from a cross between the hulled barley cultivar Valier and a hull-less Swiss landrace line, PI370970. Valier has a high acid detergent fiber content (ADF) and low starch and protein while PI370970 contains low ADF and high starch and protein content. To detect associated QTLs, data were collected and analyzed from irrigated and rain-fed environments. A total of 30 main effect QTLs and four epistatic QTLs were identified which conditioned ADF, starch and protein content under rain-fed, irrigated and combined analyses. These QTLs were located on chromosomes 2H, 3H, 5H, 6H and 7H. Major ADF and starch QTL were identified on chromosome 7H near the nud locus (the locus controlling hulled vs. hull-less caryopsis). High heritability estimates for both ADF and starch content suggest that early selection for these traits during breeding would be productive. Low ADF-QTL were independently verified in a second population in a different genetic background.     

Quantitative trait loci for dry matter digestibility and particle size traits in two-rowed × six-rowed barley population

More than half of the barley grown in the USA is used for livestock feed, with the remaining stocks diverted for human food and malting purposes. The use of barley grain as a major source of cattle feed has been criticized because of its rapid digestion in the rumen, which can result in digestive disorders in cattle. In sacco dry matter digestibility (ISDMD) and particle size (PS) after dry rolling have been found to play a role in the feedlot performance of barley as a feed grain. Reducing the rate of ISDMD is predicted to result in significantly improved animal health and average daily gain. A recombinant inbred line population derived from a cross between a high ISDMD, two-rowed barley cultivar (Valier) and a six-rowed Swiss landrace line (PI370970) exhibiting far slower ISDMD has been developed for studying the underlying genetic locations and mechanisms of these traits. To detect associated quantitative trait loci (QTLs), we collected and analyzed data from irrigated and rain-fed environments. A significant negative correlation was observed between ISDMD and PS. High heritability estimates for ISDMD and PS suggest that early selection for these traits during breeding would be achievable. Four QTLs were identified on chromosomes 2H, 6H, and 7H, explaining 73–85% of ISDMD phenotypic variation, while three QTLs on 2H and 7H were associated with variation in PS and explained 58–77% of its variation. A major QTL on chromosome 2H tightly linked to the morphology-modifying gene vrs1 was found to dramatically control 35–62% of the phenotypic variation of ISDMD and 26–53% of that of PS. The impact of the vrs1 locus on ISDMD was validated in two populations representing different genetic backgrounds. Our results suggest that it may also be advantageous to simultaneously overlap these QTLs around the vrs1 locus.     

Selection of cowpea genotypes based on grain mineral and total protein content

Grain legumes, including cowpea, are the cheapest sources of minerals and protein to enhance human nutrition. Cultivar development and deployment of cowpea with increased grain mineral content and protein composition rely on selection of genetically unique and complementary breeding lines. The objective of this study was to assess the grain minerals and protein composition of diverse cowpea collections of eastern, southern and western Africa to select promising parents to develop a breeding population. Twenty-two genetically diverse cowpea genotypes were field evaluated using a randomised complete block design with three replications in two locations in South Africa. The dried grain mineral contents were determined using an Atomic Absorption Spectrophotometre, while the protein content was determined by the combustion method. Analyses of variance showed significant (P?<?0.05) effects of genotypes, locations and their interactions. The test genotypes showed considerable variation for the following nine mineral contents: calcium (Ca), copper (Cu), iron (Fe), potassium (K), magnesium (Mg), manganese (Mn), sodium (Na), phosphorus (P), and zinc (Zn) varying from 0.07 to 0.12?mg?kg^?1; 4.46 to 7.81?mg?kg^?1; 0.06 to 0.11?g; 11.82 to 14.45?g; 1.86 to 2.27?g; 9.24 to 13.30?mg?kg^?1; 0.26 to 0.80?g; 4.63 to 5.92?g and 0.03.00 to 0.05?g, respectively. Further, the total protein content varied from 23.16 to 28.13%. Significant correlations were detected among some mineral elements and total protein content, suggesting the possibility of simultaneous selection for these traits. The principal component analysis (PCA) identified four principal components (PCs) contributing to 70.93% of the total explained variation amongst genotypes. Overall the following genotypes with desirable grain mineral and protein attributes were selected: IT90K-59 (Ca), 98K-5301 (Ca and protein), ITOOK-1060 (Cu), ITOOK-1217 and IT845-2246 (Fe), Bensogla (K, Na, and P), TVU11424 and ITOOK-1217 (Mg), CH14 (Mn and Na), TVU12637 (Mn) and Glenda and Vuli (Zn). The selected cowpea genotypes are useful genetic resources for population and cultivar development for grain nutrients composition.     

Breeding rice for rice yellow mottle virus resistance in Sub-Saharan Africa: a review

Rice is the world’s second most produced staple cereal crop after wheat. Currently, rice production and consumption have steadily increased in Sub-Saharan Africa (SSA). To date, rice is the largest imported commodity crop in the region. The low productivity is due to a number of biotic and abiotic stresses, and socio-economic constraints. Among the biotic constraints, rice yellow mottle virus (RYMV) is the most important constraint to rice in SSA. In SSA, RYMV causes yield losses ranging from 20% to 100%. Various control strategies (host resistance, cultural practices and chemicals) have been recommended to manage RYMV epidemics. RYMV disease management through generic crop protection chemicals is not economic nor is it successful due to the presence of a large number of vector species disseminating the virus. In addition, cultural practices are ineffective against RYMV because the virus is spread by several agents, including insect vectors. The use of RYMV resistant cultivars remains the most effective, economic and environmentally friendly method for resource poor farmers. However, RYMV resistant varieties have not yet been developed and deployed in SSA. The aim of this review was to present the main components in the development of rice cultivars with RYMV disease resistance. The paper provides a comprehensive review on the genetic variability of the RYMV, its epidemiology and control measures, and the gene action responsible for RYMV resistance.

The review also summarises complementary genomic tools useful in RYMV disease resistance breeding.

Successful breeding of rice for RYMV resistance depends on the availability of genes for stable resistance, knowledge of the genetics of the host and, the availability of efficient phenotyping and pathotyping methods, and understanding of the genes involved and their pattern of inheritance. Information presented in the review can serve as a reference guide for rice breeding emphasising RYMV resistance, high yields and farmers-preferred traits.     

Preliminary investigation of the effect of ethyl 4'fluorooxanilate as a male gametocide of sweet stem sorghum

An effective male sterility system enables targeted crosses between parent plants with desired and complementary characteristics. The use of chemical hybridising agents (CHAs) to induce male sterility is quicker and more efficient than manual emasculation. This study investigated the concentration, stage of application and frequency of application of ethyl 4'fluorooxanilate (E₄FO) for inducing male sterility of sweet stem sorghum without affecting female fertility. In Trial 1, the dose rate of E₄FO was determined to optimise male sterility. In this experiment three genotypes were tested at E₄FO dose rates. In Trial 2 the frequency of application of E₄FO was determined using three sweet stem sorghum genotypes, three E₄FO doses, and six frequencies of application. Data on sterility was inferred based on seed set and seed count from the treated plants. Male sterility was achieved when E₄FO was applied during heading stage using the following rates: 1?g l^?1, 1.5?g l^?1 and 2?g l^?1, with more than one application. Applying E₄FO twice during the heading stage at a rate of 2?g l^?1 would induce male sterility in the tested sweet stem sorghum genotypes, a result that could be useful in hybrid breeding programmes.     

Groundnut (Arachis hypogaea L.) improvement in sub-Saharan Africa: a review

Groundnut (Arachis hypogaea L.) is a multi-purpose legume crop widely cultivated in sub-Saharan Africa (SSA). However, yield levels of the crop has remained relatively low in SSA owing to a range of biotic, abiotic and socio-economic constraints. A dedicated groundnut improvement programme integrating new tools and methodologies to breed varieties suitable for current and emerging agro-ecologies and market needs is essential for enhanced and sustainable groundnut production in SSA. The objective of this review is to highlight breeding progress, opportunities and challenges on groundnut improvement with regard to cultivar development and deployment in SSA in order to guide future improvement of the crop. The review analysed the role of new tools in breeding such as, high-throughput and automated phenotyping techniques, rapid generation advancement, single seed descent approach, marker-assisted selection, genomic selection, next-generation sequencing, genetic engineering and genome editing for accelerated breeding and cultivar development of groundnut.