Combining ability analysis and association of yield and yield components among selected cowpea lines

The study was carried out to determine combining ability and association of yield and yield components among crosses derived from seven selected cowpea (Vigna unguiculata (L.) Walp) parents. Twenty-one hybrids were generated from diallel crosses excluding reciprocals. Hybrids along with seven parents were studied for combining ability and phenotypic correlations for seed yield and eight yield components. The result indicated that the general combining ability (gca) and specific combining ability (sca) were significant for most characters indicating the importance of both additive and non-additive genetic components. Additive gene action was important for eight characters except pod number, whereas non-additive gene action was not important for nodule number and grain yield. Parental lines IT86D-716 and IT81D-985 were found to be good general combiners for grain yield and other traits. The most promising specific combiners for yield and yield components were from crosses including IT87D-697-2 × IT86D-716, IT88D-867-11 × IT86D-716, IT93K-624 × IT87D-697-2, and IT87D-697-2 × IT92KD-405-1. Significant positive phenotypic correlations were observed between seed yield with pod length (POL), number of pods per plant (PON), and number of seeds per pod (SPD). POL, pod number per plant, SPD, and grain yield were identified as the best selection criteria that could be used in cowpea breeding programs.     

Optimum rate of nitrogen fertilization for drip-irrigated wheat under semi-arid conditions

Limited water availability in arid and semi-arid wheat production systems increases the need of applying efficient drip irrigation systems. However, there is little information available about the optimum level of nitrogen (N) fertilization for drip-irrigated wheat. A two-years field study in the semi-arid region of Upper Egypt was carried out in a randomized complete block design to investigate the response of drip-irrigated wheat to three levels of N fertilization (N₁₂₀ = 120, N₁₈₀ = 180, and N₂₄₀ = 240 kg ha^?1). N₂₄₀ increased the uptake of N, P, and K by 66.3, 48.6, and 43.5%, respectively, as compared to N₁₂₀. The application of N₂₄₀ increased the grain yield by 28.4 and 40.4% and water use efficiency by 27.6 and 41.8% the first and second season, respectively, as compared to N₁₂₀. Based on the obtained results, it is recommended to fertilize drip-irrigated wheat by 240 kg ha^?1.     

Agro-morphological characterisation and selection of sorghum landraces

Sorghum [Sorghum bicolor (L.) Moench] grown under rain-fed conditions is frequently affected by drought stress at different stages, resulting in reduced grain and biomass yield. The aim of this study was to characterise sorghum landraces and to select farmer-preferred medium-maturing genotypes under rainfed and irrigated conditions. Hundred and ninety-six sorghum accessions were evaluated at Kobo site of the Sirinka Agricultural Research Center in 2014/2015 in Ethiopia. Data collected from 14 traits were subjected to analysis of variance, cluster analysis, Pearson’s correlation coefficient analysis, path coefficient analysis and principal component analysis (PCA). Significant genotypic differences (p?<?0.05) were observed. Medium-maturing and drought tolerant sorghum genotypes including E-72457, E-72438, E-72435, E-206214, E-72449, E-75460 and E-75458 with superior agronomic performance were recommend for large-scale production or for further breeding. The genotypes evaluated under rain-fed and irrigated conditions were grouped into five and six clusters, respectively, representing varied different heterotic groups. Grain yield had significant and positive correlation with yield-related traits assessed under the two test conditions. Further, path coefficient analysis revealed that days to maturity under rainfed condition and harvest index under irrigated condition had the highest positive direct effects on grain yield, therefore can be targets for direct selection. Overall, there was marked genetic diversity among the tested genotypes. Suitable medium-maturing farmers-preferred accessions selected from the study will be useful for effective breeding for drought tolerance and medium-maturity.     

Technology generation to dissemination: lessons learned from the tef improvement project

Indigenous crops also known as orphan crops are key contributors to food security, which is becoming increasingly vulnerable with the current trend of population growth and climate change. They have the major advantage that they fit well into the general socio-economic and ecological context of developing world agriculture. However, most indigenous crops did not benefit from the Green Revolution, which dramatically increased the yield of major crops such as wheat and rice. Here, we describe the Tef Improvement Project, which employs both conventional- and molecular-breeding techniques to improve tef—an orphan crop important to the food security in the Horn of Africa, a region of the world with recurring devastating famines. We have established an efficient pipeline to bring improved tef lines from the laboratory to the farmers of Ethiopia. Of critical importance to the long-term success of this project is the cooperation among participants in Ethiopia and Switzerland, including donors, policy makers, research institutions, and farmers. Together, European and African scientists have developed a pipeline using breeding and genomic tools to improve the orphan crop tef and bring new cultivars to the farmers in Ethiopia. We highlight a new variety, Tesfa, developed in this pipeline and possessing a novel and desirable combination of traits. Tesfa’s recent approval for release illustrates the success of the project and marks a milestone as it is the first variety (of many in the pipeline) to be released.     

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.     

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.