The Canary Islands are a Spanish archipelago, where the greatest water demand comes from agriculture. Being an outermost European region that receives a large number of tourists per year, the need for greater food sovereignty becomes more important. It is vital to undertake studies on the water footprint (WF) of the main crops, in order to identify the irrigation practices of local farmers and establish recommendations for water saving through improvement of these practices. The results of this study show that the average WF for bananas in the Canary Islands is 340.80 m3 t−1 ± 34.07 and for avocadoes is 1741.94 m3 t−1 ± 286.16. The WF models proposed can explain 92 and 86% of the total variance of the WF for banana and avocado crops, respectively. The WF of both crops can be reduced, and this work can be a starting point for improvement. Farmers will face a change in temperature and water availability due to climate change; useful water saving strategies for local farmers can now be made based on estimation of the WF with yield and net needs data.

Seed conservation of banana crop wild relatives (Musa L. spp.) is limited because of lack of knowledge about their germination ecology. Musa acuminata Colla, the most important banana crop wild relative, is distributed in tropical and subtropical Asian and Pacific rainforests and colonizes disturbed sites. The role of temperature in stimulating/inhibiting germination to detect disturbance when canopy gaps are formed is not well known. We assessed seed germination thermal requirements of three subspecies of M. acuminata using nine seed accessions which had been stored in the Millennium Seed Bank. Diurnally alternating temperature cycles were almost completely essential for germination compared with constant temperatures. Germination was optimal when the upper temperature of a diurnal cycle was at 35°C; the lower temperature of the cycle was less important. Subspecies occurrence coordinates were used to extract climate temperature data which were then compared against the temperature requirements for germination from our experiment results. Maximum temperatures of the warmest month across subspecies ranges were close to but below optimal germination temperatures, as were diurnal ranges, suggesting soil-warming at the micro-climate level following gap creation is important for M. acuminata seed germination. Additionally, pre-treatment for 3 months at 60% relative humidity at constant 25°C improved germination from 14 ± 10 (mean, standard deviation) to 41 ± 29% suggesting a period in the soil seed bank under the canopy may increase sensitivity to alternating temperature cycles. Overall viability was low (49 ± 28%), and considerable variance was caused by the different accessions. Germination remained somewhat inconsistent.

Crop wild relatives (CWRs) play a key role in crop breeding by providing beneficial trait characteristics for improvement of related crops. CWRs are more efficiently used in breeding if the plant material is genetically characterized, but the diversity in CWR genetic resources has often poorly been assessed. Seven seed collections of Musa balbisiana, an important CWR of dessert and cooking bananas, originating from three natural populations, two feral populations and two ex situ field collections were retrieved and their genetic diversity was quantified using 18 microsatellite markers to select core subsets that conserve the maximum genetic diversity. The highest genetic diversity was observed in the seed collections from natural populations of Yunnan, a region that is part of M. balbisiana's centre of origin. The seeds from the ex situ field collections were less genetically diverse, but contained unique variation with regards to the diversity in all seed collections. Seeds from feral populations displayed low genetic diversity. Core subsets that maximized genetic distance incorporated almost no seeds from the ex situ field collections. In contrast, core subsets that maximized allelic richness contained seeds from the ex situ field collections. We recommend the conservation and additional collection of seeds from natural populations, preferentially originating from the species' region of origin, and from multiple individuals in one population. We also suggest that the number of seeds used for ex situ seed bank regeneration must be much higher for the seed collections from natural populations.

Precision agriculture for banana crops has been little investigated so far. The main difficulty to implement precision agriculture methods lies in the asynchronicity of this crop: after a few cycles, each plant has its own development stage in the field. Indeed, maps of agronomical interest are difficult to produce from plant responses without implementing new methods. The present study explores the feasibility to derive a spatially relevant indicator from the date of flowering and the date of maturity (time to harvest). The time between these dates (TFM) may give insight in spatial distribution of vigor. The study was carried out using production data from 2015 acquired in a farm from Cameroon. Data from individual plants that flowered at different weeks were gathered so as to increase the density of TFM sampling. The temporal variability of TFM, which is induced by weather and operational constraints, was compensated by centering TFM data on their medians (TFMc). The mapping of TFMc was obtained using a classical kriging method. Spatial structures highlighted by TFMc either at the farm level or at the plot level, suggest that such maps could be used to support agronomic decisions.

Small-scale African farmers typically have few resources for the management of weeds and soil fertility. Weed composition varies with soil properties and crops compete with weeds for available nutrients. We conducted field surveys in four districts to study the effects of cropping systems, fallow, landscape position, and soil characteristics on weed composition and evaluated the value of weed species density in predicting soil fertility conditions. Weed density was higher with annual than for banana-based cropping systems with higher relative densities of hairy beggarticks and garden spurge and lower relative densities for Cyperus spp. and johnsongrass in the banana-based systems. The relative densities of weed species varied with the length of the postfallow period, landscape position, drainage, and soil properties. Long-term rotation of annual and perennial cropping systems may be more effective than fallow in reducing total weed numbers, but fallow may be effectively used to reduce the relative densities of tropical spiderwort, Cyperus spp., and goosegrass. Relative densities of blue couch, goosegrass, garden spurge, Cyperus spp., oxalis, and johnsongrass varied more with nutrient supply than for other species. Soil properties had less effect on the distributions of tropic ageratum, hairy beggarticks, tropical spiderwort, and smallflower galinsoga. High relative densities of blue couch and garden spurge were generally associated with low soil nutrient levels. Goosegrass, johnsongrass, and oxalis were associated with higher nutrient levels. Information on the relationship of soil nutrient levels with weed flora was used to develop a decision guide to aid farmers in the identification of areas in their fields with severe nutrient deficiencies.

Musa L. was previously separated into five sections (Eumusa, Rhodochlamys, Callimusa, Australimusa and Ingentimusa) based on basic chromosome numbers and morphological characters. However, several molecular analyses currently support restructuring of Musa species into two sections, Musa and Callimusa. The application of simple sequence repeat molecular marker analysis to Musa phylogeny provided valuable, supplemental information about the classification of, and relationships between, Musa species and subspecies. Totally, 28 accessions of Musa acuminata Colla subspecies and varieties and 25 accessions of other Musa species were evaluated; 12 primers produced 91 polymorphic bands, polymorphic information content ranged from 0.4473 to 0.8394 (average = 0.7226), indicating that the primers showed a high level of polymorphism. Our results generally agreed with previous phylogenetic analyses based on molecular data. One clade comprised species of sections Australimusa and Callimusa (X= 10/9); most species of sections Eumusa and Rhodochlamys (X= 11) formed the other clade. The relationships between most species were as expected; however, some species did not conform to findings of previous studies. A wide range of variability was observed in the M. acuminata complex. M. acuminata var. chinensis and M. acuminata subsp. 522 showed the most distant relationships to other subspecies: Musa laterita, Musa ornata and Musa velutina clustered with M. acuminata var. chinensis, suggesting that they may constitute a secondary gene pool for the improvement of cultivated bananas. Molecular data indicated that Musa tongbiguanensis Chen You & Yao-Ting Wu, which was observed and described by our research group in Yunnan, China, was a distinct, new species.

This article addresses the issues of the potential impacts of the introduction of black sigatoka into Puerto Rico under situations in which the government assists growers in managing the spread of the disease, with and without prohibitions on imports of plantains and bananas. An equilibrium displacement model is used to quantify the impact of black sigatoka. The results indicate that under both scenarios the net economic benefits to society were negative. Over the long term, the government would be well-advised to invest in research to develop plantain and banana varieties that are resistant to black sigatoka.

Because the fate of the seed rain has long been shown to be critical to understanding forest recruitment and regeneration, seed predation, seed pathogens and germination among different species was examined in primary (closed-canopy vs. tree-fall gap) and in secondary (banana vs. sugarcane vs. seeded pasture) cloud forest at Maquipucuna Reserve, Ecuador. I found (1) seed predation took more seeds than either seed pathogenic disease or germination for all tree seed species and in both forests, where the level of seed loss to predation was greatest in the closed-canopy primary forest, second largest in the tree-fall gaps and less in recovering banana, sugarcane and pasture; (2) for pathogens these trends were reversed; and (3) most seeds, that were not taken by predators or pathogens, germinated. Cecropia sp. seeds in the tree-fall gaps and Otoba gordoniifolia seeds in both closed-canopy forest and tree-fall gaps were the most significantly different among all treatments in primary forest and Solanum ovalifolia seeds in banana fields and Piper aduncum in all fields were the most significantly different among all treatments in secondary forest. I conclude that forests may recover faster after human disturbance (here agriculture) than after natural disturbances (here tree-fall).

Bananas and plantains (Musa spp.) constitute staple food for over 20 million people in Democratic Republic of Congo (DRC). Since 1960, DRC is considered as a secondary centre of plantain diversification with few unknown accessions kept in the INERA-Mulungu genebank. Through similarity coefficients, cluster (unweighted pair group method with arithmetic mean, single, complete, sequential, agglomerative, hierarchical and nested design/clustering procedure) and/or multivariate analyses, numerical morpho-taxonomy has established that this diversity is composed of 37 different accessions. Each accession expressed 98 characters among the 401 possible character states, thus providing 39,298 feature patterns (data points). The 98 characters included 32 vegetative and 66 male and female inflorescences. The accessions were clustered into three genomic groups (AAA, AAB and AABB). Subjective classification ascertained nine subgroups: AAB-Silk, AAB-Pome, AAB-Plantain, AABB-Pisang Awak, AAA-Cavendish, AAA-Ibota, AAA-Gros Michel, AAA-Green-Red and AAA-Lujugira-Mutika. Three subgroups were further divided into nine clone sets which consisted of: Dwarf and Giant Cavendish, French and Horn Plantains, and Musakala, Nfuuka, Nakitembe, Nakabululu and Beer/Mbidde within Lujugira-Mutika. Numerical morpho-taxonomy effectively indicated a relationship between the DRC and Tanzania's Musa diversity. For example, the accessions ‘Kamaramasengi’ and ‘Isangi’ were found to be similar to ‘Kisukari’ (AAB-Silk) and ‘Ngego I’ (AAB-French) common in the Tanzanian Southern Highland. Likewise, the accessions Kimalindi-fupi, Kimalindi-ndefu and Jamaica of Tanzania were duplicates of Bakurura (Kigurube), Cavendish of Butuza and Gros Michel in DRC, respectively. Moreover, numerical morpho-taxonomy confirmed the pedigree of AAB-Prata (Cibwalo) in FHIA 17 and FHIA 23 and the closeness of the ancestors of Yangambi Km5 and Gros Michel. Furthermore, numerical morpho-taxonomy established AA-Mshale malembo as one of the AAA-Lujugira-Mutika parents. Molecular investigations are finally required to confirm the genomes.

Here is a major research project that is peopling the Indian Ocean with prehistoric seafarers exchanging native crops and stock between Africa and India. Not the least exciting part of the work is the authors' contention that the prime movers of this maritime adventure were not the great empires but a multitude of small-scale entrepreneurs.

Ecosystems have long been categorized by their function and structure (Odum 1953) and dominance and diversity are among the most common structural parameters measured in plant communities. The dominance of a plant species over another has been defined by having (1) more individual plants in a given sampling plot, (2) more collective biomass, or (3) greater cover (i.e. leaf area), but implicit in all definitions is a better ability to capture resources, grow and compete. Alternatively, diversity is a community-wide parameter encompassing both the raw number of species and the distribution of individual plants among them. Combining dominance and diversity together gives curves that show the distribution of abundances within a community (Whittaker 1965, Wilson 1991) and explore how these two aspects of structure relate to each other, change over time, and compare between communities separated in time or space. These curves are also effective in displaying contrasting patterns of species richness, highlighting differences in evenness among assemblages, and comparing species abundance patterns across communities (Magurran 2004). Indeed combining the dominance of particular species and the relative importance of that species within a community can suggest a ranking in competitive success and niche differentiation.

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.

Did the banana, yam and taro arrive in Australia at the hands of Europeans or come across the Torres Strait 2000 years before? Reviewing the evidence from herbaria histories and anthropology, the authors propose a ‘hierarchy of hypotheses’ and consider a still earlier option, that these food plants were potentially grown in Australia at least 8000 years ago, while it was still joined to New Guinea. This hypothesis, first proposed by Jones and Meehan in 1989, locates early horticultural experiments among peoples too often seen as inveterate hunter-gatherers.

Black Sigatoka, caused by the leaf fungus Mycosphaerella fijiensis Morelet, is a major constraint to banana production around the world. In Ecuador, the biggest banana-exporting country in the world, this disease has become increasingly aggressive. This has resulted in more fungicide applications, which have significantly increased costs in production and for the environment. Consequently, many banana growers have shifted to organic production, which produces greater economic returns as a result of higher sale prices. In addition, production costs are lower as no fungicides are applied. These organic bananas receive substantial amounts of organic products. This study describes the black Sigatoka disease and nutrient status in an organic banana plantation and compares it with a conventionally fertilized and fungicide-treated plantation. Black Sigatoka symptoms were evaluated in the vegetative and flowering stages under both production conditions and in vitro conditions. Univariate and multivariate descriptive statistics were used to analyze the parameters. Disease symptoms were more severe in leaves from the organic field than in leaves from the inorganic field, but the nutrient status (soil and foliar) did not differ between the two farms. Banana plants from the organic farm had 12 functional leaves at flowering and eight functional leaves at harvest. Average banana yields were over 40% lower for organic versus inorganic management; however, the average price received for organic bananas was over two times higher. Profit–cost analysis has shown that the organic banana farm was substantially more profitable than the inorganic one during the time period analyzed. These results indicated that bananas can be grown commercially without fungicides, and the lower productivity levels are compensated by higher prices of organic fruits in international markets. In addition, organic production has beneficial impacts on social and environmental issues.

Aspidiotus destructor Signoret (coconut scale) occurs on bananas in Hawaii, infesting leaves and fruit. Seasonal population fluctuations on two banana varieties and a preliminary sampling plan for management decision making are described. There were distinct seasonal variations in A. destructor numbers on bananas in Hawaii and varietal differences in population densities and proportions of plants infested, with cv. Cavendish incurring highest A. destructor populations. An aggregated dispersion was found for A. destructor. A preliminary sequential sampling plan based on a nominal threshold is provided.

The effect of covering post-harvest banana stumps with soil on banana weevil Cosmopolites sordidus (Germar) oviposition levels was investigated at three locations, Sendusu, Kawanda Agricultural Research Institute (KARI) and Ntungamo district of southwestern Uganda. In the first experiment oviposition levels were assessed in a banana system comprising growing plants and residues. Oviposition increased on sword suckers, reaching a peak 1–7 days after harvest and decreased thereafter. In the second experiment conducted on farmers' fields, corms received 70% of the eggs and pseudostems 30%. The area 5–10 cm below the collar received 27% of the eggs, the area 0–5 cm above the collar 30% and the area 5–10 cm above the collar 0.3%. The remaining eggs (43%) were laid 0–5 cm below the collar. The effect of stump height and covering the stumps was evaluated in both the wet and the dry seasons at Kawanda and Ntungamo. Cutting stumps to the ground level alone had no effect on oviposition. Covering post-harvest banana stumps reduced C. sordidus oviposition in the wet but not in the dry season.

The banana weevil, Cosmopolites sordidus (Germar), is a nocturnal insect that is not readily observed in banana fields. Knowledge on its distribution is essential for the design of management strategies that target the adult stage. Marked weevils were released into seven-year-old banana plots. Ten days later the plots were systematically sampled for adult weevils by first removing the banana leaf mulch and residues, searching subsections of the soil to depths of 3 and 25 cm and, finally, removal and dissection of the banana mats. Of the marked weevils, 62, 56 and 82% respectively, were recovered in three trials. Most weevils were found in close association with either the banana mat (46–66%) or with cut residues lying on the ground between the mats (24–31%). Lesser numbers were found in the leaf mulch and in the top 3 cm of soil away from the mat. The distribution of weevils is likely to be influenced by crop management practices and the availability of residues and by the presence of mulch. Implications for banana weevil IPM are discussed.

The influence of banana weevil, Cosmopolites sordidus (Germar)(Coleoptera: Curculionidae), population density on oviposition rates and larval survivorship was studied in the laboratory at the Kawanda Agricultural Research Institute in Uganda. This study was undertaken to elucidate the relationship between density-dependent factors and rates of banana weevil increase in the field. Oviposition substrates (corm pieces) were offered to a range of densities of weevils maintained in buckets. Mean oviposition rates per female at densities of 10, 20 and 40 females per bucket were 29, 37 and 53%, respectively, lower than that at a density of 5 females. Nevertheless, total oviposition for the same groups was 1.4, 2.5 and 3.7 times higher than that of the 5-female group. Providing fresh corms daily instead of every five days did not increase oviposition. Larval survivorship was slightly higher at lower densities of immatures following insertion of different densities of eggs or first instars into banana corms. The results suggest that density-dependent factors can influence oviposition rates of individual weevils and survivorship of immatures, but appear to exert only modest influence in reducing banana weevil population growth. More likely, high mortality of weevil immatures under field conditions and/or higher rates of adult mortality and emigration than previously postulated contribute to the slow population build-up of this pest.

Very little is known about the physiological interactions between plant hosts and symptomless endophytic fungi despite their widespread occurrence. We investigated the impact of two such fungi, Colletotrichum musae and Fusarium moniliforme, upon the photosynthetic capacity of two crop plants, banana and maize, respectively. Endophyte-free plants were obtained first and then infected with the fungi. Measurements of total chlorophyll content revealed very little difference between endophyte-free and infected plants of banana, whereas in maize they showed 50% reductions in the endophyte-infected plants. The maximum photochemical capacity (Fv/Fm ) was measured in order to determine if the plants had any photoinhibitory effect caused by biotic or abiotic factors. After 45 d of growth, endophyte-free banana plants had similar values of Fv/Fm to plants typical of nonstressed conditions, whereas the endophyte-infected plants showed a reduction of approx. 15%. Unlike banana, infected maize plants displayed values of Fv/Fm similar to those of control and endophyte-free plants, indicating that the maximum photochemical capacity was not affected by infection. The light response curves of both species showed that the photosynthethic capacity was severely reduced in endophyte-infected plants, reaching saturation at c. 400 μmol m−2s−1 whereas the control and endophyte-free plants were saturated at much higher photon flux densities. In banana the effect seemed to be due to an impairment of electron transport in the thylakoid membranes. By contrast, reduction of the photosynthetic capacity in maize was due to a reduction in chlorophyll content, leading to a decrease in the electron transport components and a consequent reduction in carbohydrate synthesis. It is possible that the reduction in the maximum yield of photosynthesis in both crops was caused by toxins produced by the fungi. Nevertheless there were no major macroscopic effects on the plants to indicate disease symptoms.