Highland Banana Research Articles

The Genetic Homogeneity of Uganda’s East African Highland Bananas (Mutika/Lujugira) Does Not Match the Extensive Morphological Variation Identified in this Subgroup

The East African Highland banana (Mutika/Lujugira subgroup) is composed of triploid (AAA) cooking and beer banana varieties that are adapted to the high-altitude region of the Great Lakes region of East Africa. Banana production is affected by several biotic and abiotic factors. Breeding opportunities in bananas are limited due to female sterility and parthenocarpy. The genetic diversity of crops enables breeders to develop new germplasm. Molecular markers have been used widely to dissect crop plants’ genetic diversity. This study assessed the genetic variation in 27 varieties from the Mutika/Lujugira subgroup using random amplified polymorphic DNA (RAPD). No genetic variation was observed among the banana varieties, and the 18 ten-mer primers produced monomorphic banding profiles. The genetic homogeneity of this banana subgroup is not congruent with their extensive morphological variation. Domestication and the bottleneck effect are often cited as the cause of reduced diversity in crop plants. On the other hand, several mechanisms, including somatic mutations, transposable elements, polyploidy, genome plasticity, and epigenetic mechanisms, are known to increase plant phenotypic variability. Further in-depth research is needed to explain the puzzle between the genetic and morphological diversity in the Mutika/Lujugira subgroup.

Pseudocercospora fijiensis mycelia-based infection system enhances investigational efficacy of P. fijiensis-banana pathosystem

Screening procedures for black Sigatoka have limitations. Thus, there is need for alternative screening procedure. A robust controlled-environment methodology for testing reaction of banana genotypes to Pseudocercospora fijiensis is, thus, still required. The objective of this study was, therefore, to assess the effect of P. fijiensis fragmented mycelia-based inoculum on black Sigatoka development in banana under screen house conditions with the view of developing a procedure for early assessment of resistance. Black Sigatoka severity increased significantly (P < 0.05) over time in all genotypes apart from Kayinja. Significant differences (P < 0.05) in severity were also recorded among the genotypes at 3, 4, 5 and 6 weeks after inoculation. All east African highland banana and plantain genotypes tested exhibited susceptible reaction, characterized by rapid progression of symptoms to necrotic lesions. Kayinja and M9 hybrids exhibited resistant reactions, characterized by small necrotic specks and chlorotic or brown blotches, respectively. The fragmented mycelia-based infection system classified the banana genotypes into resistant and susceptible clones, making it a reliable and efficient infection technique to assess black Sigatoka disease damage. The infection system is recommended for early screening for black Sigatoka resistance.

Analysis of essential oil and volatile components of different organs of isgin (Rheum ribes L.) plant by ultrasound-assisted extraction method

Rheum ribes L. belongs to the family Polygonaceae and is locally known as "ışkın, ucgun, highland banana". In this study, ultrasound-assisted extraction with a solvent mixture of methanol: ethyl acetate was used to isolate the volatiles of the plant from the root, stem, and leaf organs. The essential oils were extracted from the plant roots by water distillation to determine the essential oil content and composition. GC-MS (Gas Chromatography-Mass Spectrometry) was used to analyse the content of essential oils and extracts. Carvacrol (40.41%) and gamma-terpinene (%22.90) were used in the root extracts of the plant., 2,4-ditert-butylphenol (20.76%) and carvacrol (13.52%) in the stem extracts and 2,4-ditert-butylphenol (25.87%) and methyl formate (6.87%) in the leaf extracts. The volatile components of 6-butyl-3-methoxy-2-cyclohexen-1-one (30.06%) and 3-carene (16.42%) were found in the essential oil. When the structure of the volatile components in both the extract and the essential oil of the plant is examined, the presence of versatile volatile components that can be used in the production of pharmacological, bioactive, flavouring, dye material, and perfume indicated that the plant can be used as an important medicinal and aromatic plant source.

Analysis of association of sensory and laboratory assessments for quality and consumer acceptability of steamed East Africa highland bananas.

The relevance of several characteristics for the acceptability of steamed East Africa bananas (matooke) was assessed using consumer-preferred characteristics, the overall liking scores, check-all-that-apply (CATA) and the Just About Right scale. The study was conducted in rural and urban locations in three banana growing regions of Uganda. Two landraces and two hybrids were processed into matooke. Twelve trained panellists evaluated color, taste and texture sensory characteristics. Consumers scored matooke from landraces as the most liked. The CATA test showed that the most important characteristics were: smooth mouthfeel, soft to the touch, not sticky, moldable, deep yellow color, attractive, good matooke taste and smell. Principal component analysis confirmed that most of the preferred sensory characteristics were associated with the local genotypes, whereas the less preferred characteristics were associated with hybrids. Correlation analysis revealed strong positive correlations between the consumer assessed characteristics, hardness by touch, softness to touch and yellowness, as well as quantitative laboratory characteristics (moldable, hardness by touch, softness and yellowness) of the steamed matooke. Color assessed by consumers was strongly correlated with the laboratory-assessed color indicators. The strong associations observed between laboratory-assessed and consumer-based characteristics (moldable by touch and yellowness) suggest the possibility of predicting consumer characteristics using quantitative laboratory sensory assessments. Matooke taste as assessed by consumer panel is strongly associated with smooth texture and deep yellow color, which were the characteristics associated with landraces in the laboratory sensory assessment. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Transgenic East African Highland Banana Plants Are Protected against Radopholus similis through Host-Delivered RNAi.

The burrowing nematode Radopholus similis is considered a major problem of intensive banana cultivation. It can cause extensive root damage resulting in the toppling disease of banana, which means that plants fall to the ground. Soaking R. similis in double-stranded (ds) RNA of the nematode genes Rps13, chitin synthase (Chs-2), Unc-87, Pat-10 or beta-1,4-endoglucanase (Eng1a) suppressed reproduction on carrot discs, from 2.8-fold (Chs-2) to 7-fold (Rps13). The East African Highland Banana cultivar Nakitembe was then transformed with constructs for expression of dsRNA against the same genes, and for each construct, 30 independent transformants were tested with nematode infection. Four months after transfer from in vitro culture to the greenhouse, the banana plants were transferred to a screenhouse and inoculated with 2000 nematodes per plant, and thirteen weeks later, they were analyzed for several parameters including plant growth, root necrosis and final nematode population. Plants with dsRNA constructs against the nematode genes were on average showing lower nematode multiplication and root damage than the nontransformed controls or the banana plants expressing dsRNA against the nonendogenous gene. In conclusion, RNAi seems to efficiently protect banana against damage caused by R. similis, opening perspectives to control this pest.

Genetic Mapping, Candidate Gene Identification and Marker Validation for Host Plant Resistance to the Race 4 of Fusarium oxysporum f. sp. cubense Using Musa acuminata ssp. malaccensis.

Fusarium wilt of banana is a devastating disease that has decimated banana production worldwide. Host resistance to Fusarium oxysporum f. sp. Cubense (Foc), the causal agent of this disease, is genetically dissected in this study using two Musa acuminata ssp. Malaccensis segregating populations, segregating for Foc Tropical (TR4) and Subtropical (STR4) race 4 resistance. Marker loci and trait association using 11 SNP-based PCR markers allowed the candidate region to be delimited to a 12.9 cM genetic interval corresponding to a 959 kb region on chromosome 3 of 'DH-Pahang' reference assembly v4. Within this region, there was a cluster of pattern recognition receptors, namely leucine-rich repeat ectodomain containing receptor-like protein kinases, cysteine-rich cell-wall-associated protein kinases, and leaf rust 10 disease-resistance locus receptor-like proteins, positioned in an interspersed arrangement. Their transcript levels were rapidly upregulated in the resistant progenies but not in the susceptible F2 progenies at the onset of infection. This suggests that one or several of these genes may control resistance at this locus. To confirm the segregation of single-gene resistance, we generated an inter-cross between the resistant parent 'Ma850' and a susceptible line 'Ma848', to show that the STR4 resistance co-segregated with marker '28820' at this locus. Finally, an informative SNP marker 29730 allowed the locus-specific resistance to be assessed in a collection of diploid and polyploid banana plants. Of the 60 lines screened, 22 lines were predicted to carry resistance at this locus, including lines known to be TR4-resistant, such as 'Pahang', 'SH-3362', 'SH-3217', 'Ma-ITC0250', and 'DH-Pahang/CIRAD 930'. Additional screening in the International Institute for Tropical Agriculture's collection suggests that the dominant allele is common among the elite 'Matooke' NARITA hybrids, as well as in other triploid or tetraploid hybrids derived from East African highland bananas. Fine mapping and candidate gene identification will allow characterization of molecular mechanisms underlying the TR4 resistance. The markers developed in this study can now aid the marker-assisted selection of TR4 resistance in breeding programs around the world.

What future for banana-based farming systems in Uganda? A participatory scenario analysis

CONTEXTPopulation pressure, land scarcity and encroachment of nature reserves are challenging sustainable intensification of agriculture in Uganda. One of the main staple crops in Uganda is East African Highland banana. Area expansion and improved management have enhanced the economic performance of banana, yet at the expense of food security, environmental and social sustainability. While a transition of banana-based farming systems to a more sustainable future seems necessary, the desired future state and pathways of getting there may differ among actors involved. OBJECTIVESOur study aimed to co-design potential transition pathways with stakeholders along the banana value chain in Uganda, and to assess the effects of these pathways on sustainability indicators at the household level. METHODSWe conducted a participatory scenario analysis consisting of: 1) stakeholders envisioning and backcasting a sustainable future for two banana-based farming systems in Uganda; 2) researchers developing and quantifying plausible future scenarios to assess their effects on locally-relevant sustainability indicators at the household level; 3) stakeholders reflecting on the results, including synergies and trade-offs between sustainability indicators. RESULTS AND CONCLUSIONSStakeholders' envisioned future combined with main trends influencing banana-based farming systems resulted in four contrasting scenarios: Marginalisation (stagnation compared with the reference baseline); Business as usual (extrapolation of historic trends); Intensification (including Integrated Soil Fertility Management and collective marketing of banana); and Transformation (irrigation in banana, balanced crop nutrient management, cooperatives, and increased farm sizes for some as other households leave agriculture).Compared with the current baseline situation, selected sustainability indicators food self-sufficiency and farm gross margins decreased in Marginalisation, but improved in all other scenarios. Soil nutrient balances were unfavourable in all scenarios, except with balanced crop nutrition in Transformation. Stakeholders recognised labour as a main trade-off for desired improvements in other sustainability domains. Stakeholders also reflected on benefits and risks of a continued specialisation in banana, and fiercely debated the desirability of mineral fertilizer use.The active involvement of stakeholders in providing the building blocks for the scenarios, identifying relevant indicators and reflecting on the results, aimed to guide stakeholders on concrete entry points for improving sustainability of the system. SIGNFICANCEIndications of stakeholder commitment towards a more sustainable future included a convergence of ideas on the need for Integrated Soil Fertility Management, collaboration in cooperatives and the need for savings to overcome risks of specialising in banana. Meanwhile, higher-level advocacy and support is required in decision-making on more complex, long-term challenges.

Evaluating combined effects of pesticide and crop nutrition (with N, P, K and Si) on weevil damage in East African Highland Bananas.

Banana weevil (Cosmopolites sordidus, Germar) is a major pest in East African Highland Banana. The influence of crop nutritional status on weevil damage is poorly understood. Nutrient availability affects the nutritional quality of plants for weevils and may affect weevil damage. Here, we evaluate the effect of insecticides alone and in combination with fertilisers (N, P, K and Si) on weevil damage using data from two experiments in central and southwest Uganda. In the first experiment, we varied chlorpyrifos and application rates of N, P and K. In the second experiment, we varied the application rates of K and Si. Treatment effects were analysed using generalised linear mixed models with a negative binomial distribution. In the first experiment, chlorpyrifos reduced and N increased weevil damage, while P and K had no significant effect. In the K or Si application rates reduced weevil damage compared with the control. We conclude that the combined application of chlorpyrifos with K and Si fertilisers can contribute to weevil damage control on sites with low nutrient availability and should form part of integrated weevil management in bananas. Future studies should assess how much reduction in insecticide use is possible in EAHB with judicious input rates.

Endophytic fungi improve management of the burrowing nematode in banana (Musa spp.) through enhanced expression of defence-related genes

Summary The root-burrowing nematode, Radopholus similis, is reputedly the most damaging nematode pest of banana and responsible for major production losses. In this study, the endophytic potential of 13 fungal isolates was assessed for the management of R. similis in East African Highland bananas (‘Ng’ombe’). All isolates successfully colonised tissue-cultured banana roots, with isolates from Trichoderma, Fusarium and Hypocrea producing the highest (⩾49.1%) and Beauveria isolates the lowest (⩽14.4%) colonisation. The fungal endophytes T. asperellum (ICIPE 700) and H. lixii (ICIPE 697) were the most effective in reducing R. similis densities (>81%) relative to the non-inoculated control. However, the combined inoculation of ICIPE 700 and ICIPE 697 led to greater suppression of R. similis (>21%) relative to individual inoculation. Suppression of R. similis following inoculation of banana roots with ICIPE 700 and/or ICIPE 697 was associated with the significant upregulation of the defence-related gene PR-1, the cell signalling gene calmodulin Ca2+ and the cell-wall-strengthening gene β-1,3-glucan synthase. This study demonstrates the potential for nematode management in bananas with fungal endophytes, especially using the isolates ICIPE 700 and ICIPE 697 when combined.

Comparative effects of nitrogen, phosphorus and potassium on Radopholus similis infection in East African highland banana plants as influenced by rhizosphere biota

Root parasitism by Radopholus similis may vary under different nutritional conditions and soil substrates. Such variations in nematode infection may affect deductions from evaluations of pest control measures. Three parallel factorial experiments (nutrients × soil sterility × nematode) were conducted to investigate the effects of N-P-K and soil biota on R. similis infection and banana plant growth. Chlorophyll content was lower in plants receiving N-deficient solution or water only, especially in non-sterile soil. Plants were larger in non-sterile than in sterile soil; but smaller when receiving N-deficient solution or water only. Compared to complete nutrient solution (CNS), R. similis density was higher and root death lower in plants receiving N-deficient solution or water, but not different when P-deficient and K-deficient solutions were applied. Compared to CNS, root necrosis was higher in P-deficient and lower in K-deficient plants, but not different in plants treated with N-deficient solution or water only. Root damage and R. similis density were lower in non-sterile than in sterile soil. Plants inoculated with R. similis were larger and appeared greener with tendency to have higher leaf concentrations of N, P, K, Ca, Mg and Zn, than those without the nematode inoculant when treated with N-deficient solution. Deficiency in N, P or K was associated with reduced root colonization by native Fusarium, but was enhanced by R. similis under N-deficiency. Optical density of root extracts was lower in R. similis-inoculated banana plants when grown in sterile soil, but was higher in the nematode-inoculated banana plants in non-sterile soil. It is concluded that, the multiplication of R. similis in banana roots and its associated root damage and plant growth suppressive activities can vary due to plant N-P-K nutrition and the presence of rhizosphere biota, with the nematode pest even being potentially beneficial to banana plants, especially those growing under nitrogen-limited conditions.

The Status of Research for the Management of the Banana Weevil, Cosmopolites sordidus (Germar) (Coleoptera: Curculionidae) in Sub-Saharan Africa

The banana weevil Cosmopolites sordidus (Germar) (Coleoptera: Curculionidae] is a major pest of East African highland bananas and plantains. Its larvae bore in corm tissue damaging the root system, disrupting nutrient and water uptake, compromising plant anchorage, reducing yield, and shortening plantation life. Yield losses in bananas and plantains may exceed 50%. Available technologies for the management of the pest include cultural control, biological control, and chemical control. These methods may be costly, labor intensive, or ecologically unsustainable. Such effects, together with developed pesticide resistance, have led to various efforts searching for sustainable alternatives. To achieve this, there is a need to understand the biology of the pest and the currently available management options which includes use of cultural practices, resistant banana varieties, biological and microbial control, pheromone trapping and chemical and botanical insecticides. This article reviews the research status concerning C. sordidus biology, distribution, management options, including current innovations such as genome editing, and suggests future research directions for the management of the pest. Research findings suggest that no single control strategy will provide complete control. The integration of appropriate conventional C. sordidus management options with genetic engineering and other ecologically friendly methods such as use of botanicals and infochemicals will manage the pest and sustainably increase banana production.

First Report of Banana Bunchy Top Virus in Banana and Plantain (Musa spp.) in Tanzania.

Banana (including plantain; Musa spp.) is an important vegetatively propagated food staple grown as a semi-perennial crop in fields and backyard gardens in Tanzania. Banana bunchy top disease (BBTD), caused by the banana bunchy top virus (BBTV, genus Babuvirus), is the most economically important viral disease of banana, infection of which results in severe stunting and reduction in fruit production by 90-100% within two seasons. The virus is spread by the banana aphid, Pentalonia nigronervosa, and through vegetative propagation of infected sources. BBTV is an introduced virus first reported in sub-Saharan Africa (SSA) in the 1960s in the Democratic Republic of Congo. Since then, BBTV spread was confirmed in 15 countries in Central, Southern, and Western African regions but was not detected in any previous surveys in the East African sub-region. During banana pests and disease surveys conducted in December 2020 - January 2021 in Buhigwe District in the Kigoma Region of Tanzania revealed banana plants with typical BBTV symptoms (severe stunting, leaves with shortened petioles, chlorotic streaks, and yellow leaf margins) in several banana fields in Muhinda (lon. 29.78662, lat. -4.53672) and Mwayaya (lon. 29.8218, lat. -4.49203) villages. Most of the affected plantations were 5 to 15 years old. Leaf samples (N=21) from symptomatic (N=6) and asymptomatic (N=15) banana plants were collected and used for total DNA extraction and BBTV detection by polymerase chain reaction (PCR) using the primer pair BBTV-1 and BBTV-2 to amplify ~240 bp sequence of DNA-R encoding for core master replication initiator protein gene. All samples from symptomatic plants tested positive and asymptomatic plants were negative. To further confirm the virus identity, four samples, each from symptomatic (PCR positive) and asymptomatic (PCR negative) plants from Muhinda and Mwayaya villages, were tested by Triple Antibody Sandwich-Enzyme-linked Immunosorbent Assay (TAS-ELISA) using BBTV ELISA reagent set (Cat. # SRA24700-1000, Agdia, France) following the manufacturer's protocol. Samples from symptomatic plants reacted positively in TAS-ELISA, and asymptomatic plants were negative. The 240-bp PCR product of two isolates was purified, and both strands were sequenced. A BLAST search of the nucleotide sequences (NCBI GenBank Acc.# MW711671 and MW711672) revealed 99% identity with DNA-R sequences of several other BBTV isolates from Africa (Acc. No# JF755994). Further analysis of the 240-bp nucleotide sequences with Maximum-likelihood phylogenetic analysis using MEGA-X software has grouped the two BBTV sequence isolates with the SSA sub-clade of the South-Pacific group. To our knowledge, this is the first report of BBTV infecting bananas in Tanzania, and East Africa endowed with rich banana diversity and popular East African Highland banana clone. BBTV presents a new threat to banana production in this sub-region due to the high risk of further spread through vegetative propagation, traditional planting material exchange practices, and the ubiquitous banana aphid vector. This study warrants delimitation surveys to assess the extent of spread, with simultaneous efforts to raise awareness about BBTD recognition and control measures among banana growers, including eradicating infected mats and replanting with healthy planting material to recover banana production.

Mapping spatial distribution and geographic shifts of East African highland banana (Musa spp.) in Uganda.

East African highland banana (Musa acuminata genome group AAA-EA; hereafter referred to as banana) is critical for Uganda’s food supply, hence our aim to map current distribution and to understand changes in banana production areas over the past five decades. We collected banana presence/absence data through an online survey based on high-resolution satellite images and coupled this data with independent covariates as inputs for ensemble machine learning prediction of current banana distribution. We assessed geographic shifts of production areas using spatially explicit differences between the 1958 and 2016 banana distribution maps. The biophysical factors associated with banana spatial distribution and geographic shift were determined using a logistic regression model and classification and regression tree, respectively. Ensemble models were superior (AUC = 0.895; 0.907) compared to their constituent algorithms trained with 12 and 17 covariates, respectively: random forests (AUC = 0.883; 0.901), gradient boosting machines (AUC = 0.878; 0.903), and neural networks (AUC = 0.870; 0.890). The logistic regression model (AUC = 0.879) performance was similar to that for the ensemble model and its constituent algorithms. In 2016, banana cultivation was concentrated in the western (44%) and central (36%) regions, while only a small proportion was in the eastern (18%) and northern (2%) regions. About 60% of increased cultivation since 1958 was in the western region; 50% of decreased cultivation in the eastern region; and 44% of continued cultivation in the central region. Soil organic carbon, soil pH, annual precipitation, slope gradient, bulk density and blue reflectance were associated with increased banana cultivation while precipitation seasonality and mean annual temperature were associated with decreased banana cultivation over the past 50 years. The maps of spatial distribution and geographic shift of banana can support targeting of context-specific intensification options and policy advocacy to avert agriculture driven environmental degradation.

Increased Yield and High Resilience of Microbiota Representatives With Organic Soil Amendments in Smallholder Farms of Uganda.

Organic matter inputs positively affect soil fertility and quality but management effects on the soil and plant microbiome are less understood. Therefore, we studied the response of microbial colonization of the East African highland banana cultivar “Mpologoma” (AAA genome) under different mulch and manure treatments on three representative smallholder farms in Uganda. In general, the gammaproteobacterial community appeared stable with no significant response to organic matter inputs after 24 months of treatment. Significant differences (p < 0.05) in the plant-associated carpo-, phyllo-, and rhizosphere microbial community composition and diversity were found among individual sampled farms, independent of added soil inputs. Across farms, banana fruit harbored a richer and more balanced gammaproteobacterial community than the rhizo- and endospheres. Gammaproteobacterial beta diversity was shaped by the microenvironment (44%) as well as the sampling site (4%). Global effects of treatments in the rhizosphere analyzed using linear discriminant analysis effect size showed significantly enriched genera, such as Enterobacter, under manure and mulch treatments. As shown in previous works, bunch size and total yield were highly increased with manure and mulch, however, our results highlight general short-term microbial stability of Ugandan banana cropping systems with increases in the gammaproteobacterial community.

Effects of Ripeness and Blending Speed on the Extraction Yield and Physical Chemical Properties of Low Viscosity Banana Juice

Low viscosity banana juice can be extracted from banana by blending and pressing the resulted semi-solid pulp to separate the juice. This juice extraction technology is relatively new and further studies to understand key parameters for juice release is vital for scaling up production and commercialisation. This study, investigated the influence of blending speed and ripeness stage on banana juice yield using two banana cultivars; the East African highland banana (Mbile) and the exotic banana (Pisang awak). Types of sugars and organic acids in the juice were analysed using an HPLC. Changes with ripening of fruit firmness, juice pH and soluble solids were also examined. The juice yield increased significantly (p &lt; 0.05) with increasing blending speed and ripeness stage for all cultivars. The Mbile cultivar from Kagera had the highest juice yield of 82.35%, followed by Mbile cultivar from Kilimanjaro with 75.30% and Pisang awak cultivar with juice yield of 62.50%. The highest juice yield for all cultivars was achieved at 3500 rpm blending speed and ripeness stage 5. Fructose and glucose sugars increased significantly (p &lt; 0.05) with ripeness, while sucrose showed insignificant changes. Malic and citric acids were observed to increase significantly (p &lt; 0.05) during ripening in all banana cultivars.&#x0D; Keywords: East African highland banana, Banana juice extraction, Blending speed, Low viscosity banana juice.

Separate and Joint Interests: Understanding Gendered Innovation Processes in Ugandan Farm Systems

Agricultural innovation is considered paramount in solving poverty, food insecurity and malnutrition in the global south and notably in the East-African highlands. However, processes of change surrounding innovation in agriculture, and potential gender differences in their impacts, are often poorly understood. This paper resorts to principles from Farming Systems Research (FSR) and social gender analysis to study agricultural innovation processes and increase the understanding of the differential ways men and women engage with and are impacted by agricultural innovation(s). We analyze qualitative data from six Focus Group Discussions conducted in each of the two study communities located in Central and Western Uganda. These data focus on the most important agricultural innovations as perceived and assessed by men and women in their community. We list and discuss these most important innovations and further zoom in on one innovation per site: “Use of herbicides in maize production” in Central Uganda and “New agronomic practices for intensified highland banana production” in Western Uganda. Results clearly show that women's and men's domains are not separated as superficially might appear. Women and men have both separate and joint interests and adoption of an innovation by one gender, will affect the other too. The effects are multifold, with positive and negative elements. Women's ability to innovate is constrained as compared to men because gender norms limit women's agency in relation to mobility and financial independence amongst others. The two innovations studied were found to alter some gender roles and relations but did not unambiguously contribute to increasing gender equality.

Manure matters: prospects for regional banana-livestock integration for sustainable intensification in South-West Uganda

ABSTRACT In South-West Uganda, manure is highly valued for sustaining yields of East African Highland Banana, but it is in short supply. As a result, banana growers import manure from rangelands up to 50 km away. We aimed to explore the potential of this regional banana-livestock integration to meet crop nutrient requirements for sustainable intensification of banana cropping systems. We used a mixed-methods approach supported by detailed data collection. Multiple spatial levels were integrated: field-level modelling to determine long-term nutrient requirements, a household-level survey to characterize farmer practices, and a regional-level spatial analysis to map banana production and manure source areas. For median to 90th percentile banana yields (37-52 t FW/ha/year), minimum K requirements were 118–228 kg/ha/year. To supply this with manure, 10.5–20.5 t DM manure/ha/year would be needed, requiring 47–91 tropical livestock units and 27–52 ha of rangeland, far more than what is potentially available currently. However, using only manure to satisfy potassium requirements increases the risk of N losses due to nutrient imbalances likely to result from large manure applications. For sustainable intensification, manure supplemented with K-based fertilizers is a better option than manure alone, as it is more cost-effective and reduces potential N losses.

English

Allometric relationships have been used widely as a fast approach to estimate biomass and leaf area in many plant species without destructive sampling. Several allometric functions have been developed to estimate above-ground biomass (AGB) in field-grown East African Highland Bananas (EAHB). However, it is not clear if these functions apply to potted apple bananas hence the need for this study. Plants were randomly selected from different treatments to make a representative sample (n=60) across the range of plant heights and vigor in the trial. For each plant, one fully expanded and unfurled leaf was randomly selected to measure and record its length (L) and width (W) at the widest point. The leaf was drawn to scale on squared paper to determine its true area, which was later compared with the area estimated as the product of L, W and an allometric correction factor. The existing and developed functions were evaluated qualitatively using unit plots and quantitatively using the root mean square error (RMSE) and squared correlation coefficient (r2). Girth at 30 cm (G-30) was the best (p&lt;0.001 and R2 = 89%) input variable for estimating apple banana AGB. It was recommended that leaf area for the potted apple banana plants can be estimated using the existing function but the developed function should estimate AGB with G-30 as the independent variable. Key words: Destructive sampling, dry matter accumulation, Musa spp-AAB, plant girth, plant height.

Traits that define yield and genetic gain in East African highland banana breeding

East African highland bananas (Musa spp. AAA group) are an important staple in the Great Lakes region of East Africa. Their production has declined due to pests and diseases. Breeding for host plant resistance is a sustainable option for addressing this challenge. Understanding the relationships between growth parameters and bunch weight (i.e., yield) is crucial to guide breeding efforts for this crop. We investigated cause-effect relationships, through path analysis, in bunch weight of East African highland banana derived hybrids, their parents and grandparents. These family structures were planted in a 7 × 8 rectangular lattice design, replicated twice. Genetic gains for bunch weight (kg plant−1) and yield potential (t ha−1 year−1) were estimated. Significant increases of bunch weight and yield potential were noted from the landrace triploid germplasm, their derived primary tetraploid hybrids and secondary triploid bred-germplasm. Path analysis revealed that fruit length, circumference and number, number of hands and plant cycle number had a direct positive effect on the bunch weight. Days to fruit filling, days to maturity and index of non-spotted leaves had indirect effects on bunch weight. The average genetic gains for bunch weight and yield potential were 1.4% and 1.3% per year, respectively. This is the first report about genetic gains in banana breeding. Our findings may be useful for assessing progress and directing future breeding efforts in banana breeding.

Infectivity of an Infectious Clone of Banana Streak CA Virus in A-Genome Bananas (Musa acuminata ssp.).

We have characterized the complete genome sequence of an Australian isolate of banana streak CA virus (BSCAV). A greater-than-full-length, cloned copy of the virus genome was assembled and agroinoculated into five tissue-cultured plants of nine different Musa acuminata banana accessions. BSCAV was highly infectious in all nine accessions. All five inoculated plants from eight accessions developed symptoms by 28 weeks post-inoculation, while all five plants of M. acuminata AA subsp. zebrina remained symptomless. Symptoms were mild in six accessions but were severe in Khae Phrae (M. acuminata subsp. siamea) and the East African Highland banana accession Igisahira Gisanzwe. This is the first full-length BSCAV genome sequence reported from Australia and the first report of the infectivity of an infectious clone of banana streak virus.