Faculty of Agricultural Sciences

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Observations on the Nile monitor lizard (Varanus niloticus, L.) in Queen Elizabeth National Park, Uganda
(African Journal of Ecology, 1983) Edroma, E. L.; Ssali, William Mamiima
The daily activity, feeding habits and intra- and interspecific relationships of the monitor lizard Varanus niloticus (L.) were studied from 07.00 to 17.00 h. The lizards basked in the mornings (07.0049.30) and afternoons (14.30-15.10). They are scavengers and predators.
Approaches to the effective utilization of Haplochromis spp. from Lake Victoria. I. Chemical composition in relation to utilization
(Journal of Food Technology, 1984) Ssali, William Mamiima; Hanson, S. W.; Knowles, M. J.
There are over 150 species of the cichlid genus Huplochrornis in Lake Victoria constituting a major underexploited food resource. As an aid to the processing of the deepwater stock, chemical composition data were obtained for the whole fish (separated into weight groups) and for the head, viscera, flesh and residual portions separately. Data are reported for lipid content, fatty acid composition, crude protein, true protein, amino acid composition, ash and moisture content.
Assessment of cassava diversity in Uganda using SSR markers
(2004) Kizito, Elizabeth B.; Castelblanco, W.; Omara, J.; Bua, A.; Egwang, T.G.; Fregene, M.; Gullberg, U.
The genetic diversity and differentiation of 272 cassava landrace accessions collected in Uganda is assessed in this study. In addition to this, 20 Tanzanian material was included from a previous study of diversity in Tanzania, 20 material from the Ghanaian germplasm bank, 20 material from Guatemala and 18 from holdings at CIAT and IITA to represent the core collection from Latin America. All together 9 groups or samples, based on country of origin, were created to study genetic diversity and differentiation within each country and among countries. Using simple sequence repeat (SSR) markers, variation in allele frequency at many unlinked loci was used to estimate the parameters of genetic diversity and differentiation, and to estimate the strengths of various forces shaping them. SSR data was analyzed by GENSURVEY (Vekemans & Lefebvre,1997), FSTAT 2.9 (Goudet, 1995) and NTSYS-PC(Rohlf, 1993). Results affirm a genetic divergence between African and Latin American accessions. They also show a high genetic diversity and a low differentiation in the Ugandan accession. There is a substantial role played by the cassava mosaic disease (CMD) on cassava genetic constitution in respective districts.
The effect of cassava mosaic disease on the genetic diversity of cassava in Uganda
(Springer International Publishing, 2005) Kizito, Elizabeth B.; Bua, Anton; Fregene, Martin; Egwang, Thomas; Gullberg, Urban; Westerbergh, Anna
Cassava (Manihot esculenta) is a tropical crop that is grown in Africa, Latin America and Southeast Asia. Cassava was introduced from Latin America into West and East Africa at two independent events. In Uganda a serious threat to cassava’s survival is the cassava mosaic disease (CMD). Uganda has had two notable CMD epidemics since the introduction of cassava in the 1850s causing severe losses. SSR markers were used to study the effect of CMD on the genetic diversity in five agro-ecologies in Uganda with high and low incidence of CMD. Surprisingly, high gene diversity was detected. Most of the diversity was found within populations, while the diversity was very small among agro-ecological zones and the high and low CMD incidence areas. The high genetic diversity suggests a mechanism by which diversity is maintained by the active involvement of the Ugandan farmer in continuously testing and adopting new genotypes that will serve their diverse needs. However, in spite of the high genetic diversity we found a loss of rare alleles in areas with high CMD incidence. To study the effect of the introgression history on the gene pool the genetic differentiation between East and West Africa was also studied. Genetic similarities were found between the varieties in Uganda and Tanzania in East Africa and Ghana in West Africa. Thus, there is no evidence for a differentiation of the cassava gene pool into a western and an eastern genetic lineage. However, a possible difference in the genetic constitution of the introduced cassava into East and West Africa may have been diminished by germplasm movement
Distribution, Timing of Attack, and Oviposition of the Banana Weevil, Cosmopolites sordidus, on Banana Crop Residues in Uganda
(The Netherlands Entomological Society, 2005-06) Masanza, Michael; Gold, C.S.; Huis, A. van
Crop sanitation (removal and chopping of residue corms and pseudostems following plant harvest) has been recommended as a ‘best bet’ means of reducing banana weevil, Cosmopolites sordidus (Germar) (Coleoptera: Curculionidae), populations. However, it has been unclear when such practices should be carried out and what types of residues should be destroyed. Therefore, trials were conducted in Uganda to determine C. sordidus distribution, timing of attack, and oviposition on crop residues and growing plants. Assessments were performed in on-station trials on different aged standing and prostrate residues by destructive sampling. Similar data were collected from farmers’ fields maintained at low, moderate, and high levels of sanitation. In the on-station trial, oviposition occurred on up to 120- day-old residues, although most occurred within 30 days of harvest. In a second on-station experiment, oviposition on standing residues was not significantly affected by residue age. By contrast, oviposition on prostrate residues was two times higher on 4-week-old than on 2-week-old residues, while the number of larvae on 8-week-old residues was three times higher than on 2-week-old residues. The number of adults was twice as high on 16-week-old residues as that on 2-week-old residues for both prostrate and standing residues. Farmers’ fields maintained at high sanitation had 50% fewer eggs per residue than farms with low sanitation levels. In general, the number of immatures per residue was 50% higher on banana corms than on pseudostems. Numbers of larvae per residue were three times more abundant at low than at high sanitation levels. Residues in fields with high sanitation supported 50% fewer adults than residues in low sanitation fields. The results suggest that removal and splitting of corms after harvest is effective and practical in destroying immature growth stages of the pest and that such practices should be carried out soon after harvest.
Quantitative trait loci controlling cyanogenic glucoside and dry matter content in cassava (Manihot esculenta Crantz) roots
(Hereditas, 2007) Kizito, Elizabeth B.; Stljung, Ann-Christin Ro¨ Nnberg-Wa¨; Egwang, Thomas; Gullberg, Urban; Fregene, Martin; Westerbergh, Anna
Cassava (Manihot esculenta Crantz) is a starchy root crop grown in the tropics mainly by small-scale farmers even though agro-industrial processing is rapidly increasing. For this processing market improved varieties with high dry matter root content (DMC) is required. Potentially toxic cyanogenic glucosides are synthesized in the leaves and translocated to the roots. Selection for varieties with low cyanogenic glucoside potential (CNP) and high DMC is among the principal objectives in cassava breeding programs. However, these traits are highly influenced by the environmental conditions and the genetic control of these traits is not well understood. An S1 population derived from a cross between two bred cassava varieties (MCOL 1684 and Rayong 1) that differ in CNP and DMC was used to study the heritability and genetic basis of these traits. A broad-sense heritability of 0.43 and 0.42 was found for CNP and DMC, respectively. The moderate heritabilities for DMC and CNP indicate that the phenotypic variation of these traits is explained by a genetic component. We found two quantitative trait loci (QTL) on two different linkage groups controlling CNP and six QTL on four different linkage groups controlling DMC. One QTL for CNP and one QTL for DMC mapped near each other, suggesting pleiotrophy and/or linkage of QTL. The two QTL for CNP showed additive effects while the six QTL for DMC showed additive effect, dominance or over dominance. This study is a first step towards developing molecular marker tools for efficient breeding of CNP and DMC in cassava.
Influence of Plant and Residue Age on Attraction, Acceptance and Larval Survival of the Banana Weevil Cosmopolites sordidus (Coleoptera: Curculionidae)
(International Journal of Tropical Insect Science, 2009) Masanza, Michael; Gold, C.S.; Huis, A. van
Laboratory trials were conducted in Uganda at the Kawanda Agricultural Research Institute to determine attraction, eclosion success and larval survivorship of the banana weevil Cosmopolites sordidus (Germar) on crop residues of different ages. In the first experiment, studies focused on different types and ages of residues of one susceptible highland banana clone ‘Nabusa’ (genome group AAA-EA). Corms attracted 65% of the test weevils, pseudostems 30%, while 5% were non-respondents. Oviposition levels and the number of eggs per female were higher on young than old corms. Eclosion rates of ,1-day-old eggs inserted into corm pieces of residues (cultivar ‘Kisansa’, genome group AAA-EA) declined from 66% in residues collected ,2 days after harvest (DAH) to 58% in residues collected .30 DAH. To assess immature survival, ,1-day-old 1st instar larvae were put on banana corms of suckers and crop residues of the cultivar Kisansa in single rearing chambers. The number of surviving individuals was recorded at 3-day intervals until adults emerged. Survivorship was 12% on sword suckers, 10% on maiden suckers and 7% on flowered plants; and 12% on residues collected ,2 DAH and 5% on residues collected .30 DAH. Larval duration and mean days taken for adult emergence increased with plant and crop residue age. Females emerging from the different plant and residues treatments were similar in weight. The data suggest that all aged residues are suitable hosts for C. sordidus, suggesting that sanitation practices should be implemented soon after harvest.
A Computer Program for Modeling the Conversion of Organic Waste to Energy
(MDPI Open access publisher, 2011) Namuli, Rachel; Laflamme, Claude B.; Pillay, Pragasen
This paper presents a tool for the analysis of conversion of organic waste into energy. The tool is a program that uses waste characterization parameters and mass flow rates at each stage of the waste treatment process to predict the given products. The specific waste treatment process analysed in this paper is anaerobic digestion. The different waste treatment stages of the anaerobic digestion process are: conditioning of input waste, secondary treatment, drying of sludge, conditioning of digestate, treatment of digestate, storage of liquid and solid effluent, disposal of liquid and solid effluents, purification, utilization and storage of combustible gas. The program uses mass balance equations to compute the amount of CH4, NH3, CO2 and H2S produced from anaerobic digestion of organic waste, and hence the energy available. Case studies are also presented.
Genetic diversity among farmer-preferred cassava landraces in Uganda
(African Crop Science Society Journal, 2012) Kizito, Elizabeth B.; Turyagyenda, L.F.; Ferguson, M.E.; Baguma, Y.; Harvey, J.W.; Gibson, P.; Wanjala, B.W.; Osiru, D.S.O.
Understanding of genetic diversity among a breeding population is an important requirement for crop improvement as it allows for the selection of diverse parental combinations and formation of heterotic pools for genetic gain. This study was carried out to determine genetic diversity within and among 51 farmer-preferred cassava (Manihot esculenta) landraces and 15 elite accessions grown in Uganda. Twenty six simple sequence repeat (SSR) markers used for genetic diversity assessment in this study revealed a total of 154 alleles, of which 24% were unique alleles present only in landraces. The genetic diversity and observed herozygosity in landraces were slightly higher than in elite accessions. Elite accessions clustered with some of the landraces indicating that there were some alleles in common. However, 58.8% of the landraces fell into 3 different clusters independent of the elite accessions. Including these landraces with unique alleles in cassava breeding schemes will increase the chances of producing farmer preferred adapted elite cultivars. The study also revealed genetic differentiation among accessions from different regions providing an opportunity for establishment of heterotic pools within a breeding programme.
Evaluation of Ugandan cassava germplasm for drought tolerance
(International Journal of Agriculture and Crop Sciences, 2013) Turyagyenda, Laban F.; Kizito, Elizabeth B.; Baguma, Yona; Osiru, David
Increased pressure on prime arable land for agriculture to meet food demand for global population has resulted in shifting agriculture to marginal areas where drought is frequent. Focusing research towards development of drought tolerant varieties is thus necessary. Replicated field trials for farmer preferred cassava genotypes were established to evaluate their morphological and yield trait responses and adaptability to moisture stress. Results showed significant (P<0.05) differences among genotypes for all the parameters evaluated. Moisture stress resulted in a decline in Harvest Index by 22.34%, Fresh Root Yield by 37.04%, Number of Roots by 19.43%, Dry matter content by 16.58%, Root starch content of 20.81%, Leaf Retention by 25.72% and Plant height by 16.62%. Results therefore, evidently showed that water stress has significant devastating effects on vegetative and yield parameters of cassava. Breeding strategies to develop drought tolerant cassava varieties to cope up with increased water scarcity and semi-arid conditions are thus paramount. Varietal variability in response to water stress reported is a cornerstone in the breeding process. Besides genetic effects were dominant indicating breeding objectives would be easily achieved. Genotypes MH96/0686, Magana, Yellow, TME 204, Nyamutukura, MH97/2961, NASE 1, NASE 2 and NASE 12 were least affected by drought and may provide gene sources for cassava improvement. Genotype x Location was significant (P<0.05) suggesting that rational distribution of genotypes to agro-ecological zones with different levels of drought stress is possible. Some genotypes had stable yield and its components suggesting that cassava can easily adapt to dry environments
Physiological and molecular characterization of drought responses and identification of candidate tolerance genes in cassava
(aobplants.oxfordjournals.org, 2013-02) Turyagyenda, Laban F.; Kizito, Elizabeth B.; Ferguson, Morag; Baguma, Yona; Agaba, Morris; Harvey, Jagger J. W.; Osiru, David S. O.
Cassava is an important root crop to resource-poor farmers in marginal areas, where its production faces drought stress constraints. Given the difficulties associated with cassava breeding, a molecular understanding of drought tolerance in cassava will help in the identification of markers for use in marker-assisted selection and genes for transgenic improvement of drought tolerance. This study was carried out to identify candidate drought-tolerance genes and expression-based markers of drought stress in cassava. One drought-tolerant (improved variety) and one drought-susceptible (farmer-preferred) cassava landrace were grown in the glasshouse under well-watered and water-stressed conditions. Their morphological, physiological and molecular responses to drought were characterized. Morphological and physiological measurements indicate that the tolerance of the improved variety is based on drought avoidance, through reduction of water loss via partial stomatal closure. Ten genes that have previously been biologically validated as conferring or being associated with drought tolerance in other plant species were confirmed as being drought responsive in cassava. Four genes (MeALDH, MeZFP, MeMSD and MeRD28) were identified as candidate cassava drought-tolerance genes, as they were exclusively up-regulated in the drought-tolerant genotype to comparable levels known to confer drought tolerance in other species. Based on these genes, we hypothesize that the basis of the tolerance at the cellular level is probably through mitigation of the oxidative burst and osmotic adjustment. This study provides an initial characterization of the molecular response of cassava to drought stress resembling field conditions. The drought-responsive genes can now be used as expression-based markers of drought stress tolerance in cassava, and the candidate tolerance genes tested in the context of breeding (as possible quantitative trait loci) and engineering drought tolerance in transgenics.
Novel Intact Bitter Cassava: Sustainable Development and Desirability Optimisation of Packaging Films
(Food Bioprocess Technol Journal, 2016) Tumwesigye, Kashub Steven; Oliveira, J.C.; Sousa-Gallagher, Maria Jose; Montañez, J. C.
Novel biomaterials and optimal processing conditions are fundamental in low-cost packaging material production. Recently, a novel biobased intact bitter cassava derivative was developed using an intrinsic, high-throughput downstream processing methodology (simultaneous release recovery cyanogenesis). Processing of intact bitter cassava can minimise waste and produce low-cost added value biopolymer packaging films. The objective of this study was to (i) develop and characterise intact bitter cassava biobased films and (ii) determine the optimal processing conditions, which define the most desirable film properties. Films were developed following a Box-Behnken design considering cassava (2, 3, 4 % w/v), glycerol (20, 30, 40 % w/w) and drying temperature (30, 40, 50 °C) and optimized using multi-response desirability. Processing conditions produced films with highly significant (p < 0.05) differences. Developed models predicted impact of processing conditions on film properties. Desirable film properties for food packaging were produced using the optimised processing conditions, 2 % w/v cassava, 40.0%w/w glycerol and 50 °C drying temperature. These processing conditions produced films with 0.3 %; transparency, 3.4 %; solubility, 21.8 %; water-vapour-permeability, 4.2 gmm/m2/day/kPa; glass transition, 56 °C; melting temperature, 212.6 °C; tensile strength, 16.3 MPa; elongation, 133.3 %; elastic modulus, 5.1MPa and puncture resistance, 57.9 J, which are adequate for packaging applications. Therefore, intact bitter cassava is a viable material to produce packaging films that can be tailored for specific sustainable, low-cost applications.
Quantitative and Mechanistic Analysis of Impact of Novel Cassava-Assisted Improved Processing on Fluid Transport Phenomenon in Humidity-Temperature-Stressed Bio-Derived Films
(European Polymer Journal, 2016) Tumwesigye, Kashub Steven; Oliveira, J.C.; Sousa-Gallagher, Maria Jose
Bio-derived films’ realistic performance integrity is ascertained by their resilience in highly stressful storage conditions, a function of its ability to respond timely and manages fluid barrier appropriately. Bio-derived films’ moisture and temperature sensitivity often posed mass transport challenges, thus decreasing their lifespan. Quantifying bio-derived film mass transport behaviour has been limited to mass transfer representations, which can be imperfect to understand fully mass transport phenomenon. This study reported quantitative and mechanistic analysis of fluid-phase mass transport phenomenon in Simultaneous Release Recovery Cyanogenesis-produced intact bitter cassava (IBC) bio-derived films under stressful conditions. Films were tested for solvent solubility, swelling ratio, sorption and permeability to water vapour and oxygen at 10-40°C and 10-95% RH. Film’s structural alterations were characterised by their thermal and chemical properties. Modified-BET, Peleg, Oswin models best described sorption data. Temperature-dependence of film water vapour permeability was simulated best by Arrhenius model, while oxygen permeability was influenced highly by crystallinity and RH. Non-organic and organic film-solvent diffusion followed case II and Fickian diffusional patterns respectively. Solvents induced structural changes in IBC films with concentration-dependent diffusion. Cassava bio-derived films’ integrity will depend on the host environment, thus maximum care should be ensured to minimise environment impact during applications. Nonetheless, IBC films hold potential as biomaterials for broad range product use.
Integrated Process Standardisation as a Zero-Based Approach to Bitter Cassava Waste Elimination and Widely-Applicable Industrial Biomaterial Derivatives
(Chemical Engineering and Processing Journal, 2016) Tumwesigye, Kashub Steven; Peddapatla, R.V.G.; Crean, A.; Oliveira, J.C.; Sousa Gallagher, Maria Jose
Integrated standardised methodology for biopolymer derivatives (BPD) production from novel intact bitter cassava was demonstrated by desirability optimisation of simultaneous release, recovery, cyanogenesis (SRRC) process. BPD were evaluated for yield and colour using buffer (0,2,4 % v/v), cassava waste solids (15,23,30 % w/w), and extraction time (4,7,10 minutes). Nearly all the root was transformed into BPD, with higher yield and colour in comparison to starch extrinsically processed. Maximum global desirability, predicted efficient material balance, buffer 4.0 %w/v, cassava waste solids 23 %w/w and extraction time, 10 minutes, producing BPD yield, 38.8 % wb Validation using buffer, 3.3% w/v, cassava waste solids, 30 % w/w and extraction time, 10 minutes, produced 40.7 % wb BPD. SEM, DSC, TGA, FTIR and moisture barrier analyses revealed a uniform microstructure and high thermal stability of BPD and film, thus demonstrating efficient performance of the standardised integrated methodology. Hence, processing intact cassava root as a standardised integrated methodology could be used to produce sustainable low cost BPD for a broad range of applications. Methodologies designed around standard integrated procedures, matching zero-based approach to contamination, are novel strategies, and if used effectively can eliminate cassava wastes and recover BPD resources as sustainable biomaterials.
New Sustainable Approach to Reduce Cassava Borne Environmental Waste and Develop Biodegradable Materials for Food Packaging Applications
(Food Packaging and Shelf Life Journal, 2016) Tumwesigye, Kashub Steven; Oliveira, J.C.; Sousa-Gallagher, Maria Jose
Transforming waste cassava into a sustainable resource requires a new approach and redesign of the current processing methodologies. Bitter cassava cultivars have been employed mainly as an emergency famine food, but could also be used as a value-added material for packaging. Processing of intact bitter cassava can minimize waste, and produce low-cost added value biopolymer packaging films for targeted applications. This study developed an improved simultaneous release, recovery and cyanogenesis (SRRC) downstream processing methodology for sustainable reduction of waste and development of film packaging material using intact bitter cassava. SRRC approach produced peeled (BP) and intact (BI) bitter cassava biopolymer derivatives. BI showed significantly higher yields ensuring 16% waste decrease with no environmental impact caused by discard residues. SRRC was very effective in reducing the total cyanogen content to within Codex minimum safety limits, demonstrating that the peeling of bitter cassava process can be avoided. Transparent films were produced using the casting method from both BP and BI derivatives. BI films were more transparent and homogeneous, less soluble, less permeable to moisture, less hydrophilic, more permeable to oxygen and carbon-dioxide, sealable, lower cost, than the BP. Hence, intact bitter cassava and SRRC can be used as sustainable, safe, integrative process solution for high value-added product (e.g., packaging film) production from low-cost biobased materials.
Effective Utilisation of Cassava Bio-Wastes Through Integrated Process Design: A Sustainable Approach to Indirect Waste Management
(Process Safety and Environmental Protection Journals, 2016) Tumwesigye, Kashub Steven; Morales-Oyervidesa, L; Oliveiraa, J.C.; Sousa-Gallagher, M.J.
An integrated process design, which can be applied in small-to-medium batch processing,was proposed. The process is based on the exploitation of intact (whole) cassavaroot, through optimisation of simultaneous release recovery cyanogenesis downstreamprocessing for sustainable wastes minimisation and packaging material development.An integrative seven unit process model flow was considered in the process design mod-elling. Using the release process models, it was possible to predict the maximum yield(45.8%) and the minimum total cyanogens (0.6 ppm) and colour difference (4.0) needed toavoid wastes and unsafe biopolymer derivatives. The process design allowed saving on theenergy and water due to its ability to reuse wastewaters in the reactions and release pro-cesses. Drying rates, Scanning electron micrograph, Differential scanning calorimetry, Watervapour transmission rate and Fourier transmission infrared spectroscopy analyses havedemonstrated the practical advantage of laminar flow hood air systems over oven-dryingheat for integrated process design.Thus, the integrated process design could be used as a green tool in production of cassavaproducts with near zero environmental waste disposal.
Integrated Sustainable Process Design Framework for Cassava Biobased Packaging Materials: Critical Review of Current Challenges, Emerging Trends and Prospects
(Trends in food science and technology, 2016) Tumwesigye, Kashub Steven; Oliveira, J.C.; Sousa-Gallagher, Maria Jose
Background: Cassava represents a reasonable share in biobased material development globally. The production of its biopolymer derivatives using conventional techniques/methods is accompanied by significant wastes with potential negative environmental impact. Among the biopolymer derivatives, starch dominates as lone additive in cast matrices with packaging limitations, requiring other biopolymer derivatives, and/or external-source modifiers for matrix improvement. exploiting integrated sustainable engineering process design of all biopolymer derivatives, is a novel approch in deaigning efficient system of cassava biobased materials for food and non-food applications. Scope and approach: A critical review on the current and emerging techniques and methodologies to address cassava wastes and challenges of cassava research for application on biobased packaging are provided. The potential of integrated sustainable engineering process design framework for packaging system is discussed, and prospects for improvement suggested. Key findings and conclusions: Challenges of significant waste generated during conventional processing and on the application process aiming at tailoring materials to industrial needs are reported. These materials should be improved using a holistic approach reflecting the target products, variable environment, minimising production costs and energy. Use of novel material resources, eliminating waste, and employing a standardised methodology via desirability optimisation, present a promising process integration tool for development of sustainable cassava biobased systems.
Abundance, distribution and effects of temperature and humidity on arthropod fauna in different rice ecosystems in Uganda
(Journal of Entomology and Zoology Studies, 2017) Kizito, Elizabeth B.; Masika, Fred Bwayo; Masanza, Michael; Aluana, Goncalves; Barrigossi, Jose Alexandre Freitas
The study on abundance, distribution and effects of temperature and humidity on arthropod fauna was conducted in smallholder rice farming areas in three agro ecological zones of Lake Victoria basin, Northern moist farmlands and Western Savannah grasslands in Uganda. Arthropods were collected using a standard sweep net and a total of 17 orders representing 13,272 arthropods were recorded from the three agro – ecological zones during the study. Most arthropod fauna were collected in Bugiri, Lira and Kasese respectively. The most abundant orders throughout the survey included Homoptera, Coleoptera, Hemiptera, Diptera, Hymenoptera and Orthoptera. While the least abundant included Dermaptera, Zoraptera, Phasmatoda, Mantodae, Embioptera and Neuroptera. All orders except Embioptera, Mantodae, Neuroptera and Phasmatoda were collected in all the three agro ecological zones. The orders Diptera (p = 0.0282), Hymenoptera (p = 0.0051), Lepidoptera (p = 0.0149), Odonata (p = 0.0356) showed a significant difference in abundance in the three agro – ecological zones. Temperature and humidity had a significant effect on the arthropod population for example Aranea showed a positive correlation in their abundance with increase in temperature in all the agro – ecologies
Evaluation of Novel Bitter Cassava Film for Equilibrium Modified Atmosphere Packaging of Cherry Tomatoes
(Food Packaging and Shelf Life Journal, 2017) Tumwesigye, Kashub Steven; Sousaa, A.R.; Oliveiraa, J.C.; Sousa-Gallaghera, Maria Jose
Equilibrium modified atmosphere packaging (EMAP) technology offers the possibility to maintain produce postharvest quality and extend its shelf-life. However, EMAP stability depends on well-tuned packaging design parameters to match environmental conditions. This study defined the design requirements of a biobased film EMAP that can preserve the quality and prolong the shelf-life of fresh cherry tomatoes under recommended and simulated abuse supply chain conditions. Optimum EMAP was evaluated based on headspace gas composition at 10–20 °C, 75–95% RH and verified by determining quality changes of packed cherry tomatoes in using a continuous or micro-perforated (0.27 μm) bio-based intact bitter cassava (IBC) film. This was compared with a non-bio-based polymer film (oriented polypropylene, OPP). The IBC film attained equilibrium O2 (2–3%) after 180 h at 10 °C, with 0 and 1 perforation, for 75 and 95% RH while OPP film maintained a downward O2 fall. Continuous and micro-perforated IBC film did not show any major differences in equilibrium headspace O2, thus perforation can be neglected. Based on desirability optimisation results, biobased IBC film demonstrated a better optimized EMAP system in attaining recommended gas and stretching cherry tomato shelf-life as compared to non-biobased (OPP) film. The application of bio-based IBC film offers new possibilities in packaging fresh produce under an equilibrium modified atmosphere without compromising its quality.
Morphological distinctiveness between Solanum aethiopicum Shum group and its progenitor
(Academic Journals, 2017-08) Kizito, Elizabeth B.; Sseremba, Godfrey; Tongoona, Pangirayi; Eleblu, John Savior Yaw; Danquah, Eric Yirenkyi; Kabod, Nahamya Pamela
Use of morphological markers offers an alternative in germplasm discrimination of research-neglected crop species. A collection of 25 accessions including five wild progenitors was evaluated in screen house to identify the morphological difference between Solanum aethiopicum Shum and Solanum anguivi. An Unweighted Pair Group Method with Arithmetic mean hierarchical clustering revealed presence of moderate structure with a cophenetic correlation coefficient of 0.73. Five distinct clusters were produced; the progenitor accessions for the S. aethiopicum Shum were grouped in their own cluster. The Richness, Shannon-Weaver and Simpson indices were also different among qualitative variable categories. A ‘prcomp’ function based Principal component analysis (PCA) in R on quantitative variables indicated that days to germination and emergence, cotyledonous leaf length, cotyledonous leaf width, shoot biomass, plant height, petiole length, days to first flowering opening, plant width, plant branching, and number of leaves per plant are the major drivers of variability in the study accessions. Further, results from canonical discriminant analysis to discern between the S. aethiopicum and its progenitor accession groups showed that the days to germination and emergence provide the best separation; with the former emerging earlier than the latter. The mean values for flowering time, leaves per plant, number of branches per plant and plant height were more favorable for the Shum than its wild progenitor accessions. The study revealed that morphological markers are useful in distinguishing between the S. aethiopicum Shum and its progenitor accessions.

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