Introduction. Nos travaux ont eu pour objectif de comparer les performances agronomiques des plants d’un hybride de bananier plantain (CRBP-39, Musa cv. AAAB) obtenus par utilisation de deux méthodes de multiplication végétative : la culture de tissus in vitro (CIV) et une technique de propagation par multiplication de plants à partir de fragments de tiges (dite technique des PIF) développée récemment. L'étude, effectuée au Cameroun, a été menée en altitude (1250 m) ; elle a porté sur un cycle de culture. L'hybride CRBP-39 a été choisi en raison de sa résistance à la maladie des raies noires et de ses performances agronomiques. Matériel et méthodes. Des vitroplants et des plants obtenus par la technique des PIF, technique de propagation horticole développée au CARBAP (Cameroun), ont été plantés séparément en blocs, dans des parcelles de terrain élémentaires de 16 plants. Aucun traitement chimique n'a été appliqué contre la maladie des raies noires. Les observations ont été faites essentiellement sur des caractéristiques agronomiques. Résultats et discussion. Pour le pied-mère, il n'y a eu aucune différence significative entre les plantes obtenues à partir de l'une ou de l’autre méthode de multiplication végétative quant à la taille et au périmètre de la pseudo-tige ; le nombre de feuilles fonctionnelles à la floraison ; la durée du cycle de production ; le poids de régime ; le nombre de mains et de fruits du régime ; la longueur et la circonférence du fruit. Pour le rejet successeur, il y a eu des différences significatives de taille et de périmètre de la pseudo-tige, ainsi que du nombre de feuilles émises et fonctionnelles à la récolte. Ces résultats montrent globalement une grande similitude des caractéristiques agronomiques des plants issus des deux méthodes de multiplication végétative. La technique des PIF, de plus en plus utilisée compte tenu de sa simplicité, son faible coût de production et sa rapidité de mise en œuvre, est donc une technique horticole qui permet de produire des plants de qualité agronomique comparable aux vitroplants.

Introduction. In the French West Indies, farmers generally consider that periodical soil tillage is necessary to increase soil porosity and maintain high yield. However, in the non-tilled perennial banana plantations of the highlands, the soil exhibits better physical and biological properties than in the conventional banana plantations. To determine if tillage before banana planting is necessary for proper banana crop functioning and to assess the effect of tillage on soil quality, banana planting after conventional tillage was compared with no-till banana planting on crop residue mulch on an experimental plot. Materials and methods. Soil quality was assessed through indicators such as porosity, organic status, microbial biomass and structure of nematode communities. Crop functioning was assessed through plant growth, root distribution, and soil water and nitrogen availability. Results. We found that tillage reduced soil microbial biomass and the number of nematode functional guilds. Tillage had only a short-term effect on soil porosity and did not allow deeper extension of the root system. Although soil organic nitrogen mineralization was higher with conventional tillage, banana nitrogen nutrition was not better, probably because the high nitrogen fertilization offset the variations in availability of nitrogen from organic origin. We found that banana growth was better with no-till treatment. This could be explained by less drying out of soil due to the crop residue mulch left on the soil surface with no-till treatment. Conclusion. Relative to conventional tillage, no-till banana planting improved soil quality and crop performance.

Introduction. Rose apple fruit ripens on the tree, has a thin peel, soft flesh and deteriorates quickly after harvest. Water loss contributes to rapid deterioration. 1-MCP can extend the postharvest life of non-climacteric fruits either directly through its effect as an ethylene blocker or through indirect effects. Materials and methods. We investigated the effect of 1-MCP (1 µL·L–1) on shelf life and quality of Rose apple fruits (Syzygium jambos Alston) cv. Tabtim Chan. Fruit were exposed to 1-MCP for (0, 6, 12, 18 or 24) h, then stored at (15 ± 1) °C for 12 days. Subsequently, we investigated the effect of 1-MCP (1 µL·L–1) for 12 h on fruit stored at 5 °C or 10 °C. Weight loss, skin colour, total soluble solids, fruit firmness and percentage of diseased fruit were measured during storage. Results. 1-MCP reduced weight loss from about 13% of initial weight to 6%, irrespective of the time of exposure. 1-MCP applied to fruit for 12 h or 18 h increased firmness from 3.2 N to 3.8 N and more than halved the percentage of fruit showing disease. Exposure to 1-MCP for 12 h or 18 h was optimum for reducing disease. 1-MCP for 12 h and storage at (10 ± 1) °C doubled shelf life to 24 days compared with fruit stored at the same temperature, but without 1-MCP. Storage at less than 10 °C did not extend shelf life any further. Conclusion. 1-MCP extended the shelf life of Rose apple fruit by reducing weight loss, maintaining flesh firmness and slowing disease development.

Introduction. Black Leaf Streak Disease (BLSD) is regarded as the most economically important threat that the banana industry has to face. Effectively, this foliar disease affects leaf photosynthesis but, above all, reduces the greenlife of fruits, that cannot be exported in cases of severe infestation. Main characteristics of Black Leaf Streak Disease. More than 20 Mycosphaerella species have been described on bananas. Leaf spot diseases of bananas are caused by some species of this complex, of which M. fijiensis (BLSD) and M. musicola (Sigatoka disease) are the most important. M. fijiensis is an invasive species that has totally replaced M. musicola in most banana-exporting countries, which was conducive to increasing difficulties in banana leaf spot control. BLSD causes increasing difficulties for control. Since all banana cultivars grown in the banana industry are highly susceptible to BLSD, the control of this disease relies on aerial applications of fungicides according to either systematic frameworks (mostly contact fungicides) or forecasting strategies (mostly systemic fungicides). In a banana-exporting country where M. fijiensis has been reported, BLSD control becomes increasingly more difficult. This evolution is essentially due to the rapid emergence of fungicide resistance, and is conducive to a significant increase in the cost of disease control but, above all, to increasing negative environmental effects. Challenges for the banana industry. Because of the rapid adaptation of M. fijiensis, the banana industry must be prepared for significant evolution. We propose various parameters that should be monitored at different levels (disease assessment parameters, evaluation of chemical control efficiency, global evaluation of BLSD economic incidence) to rationalize such evolution. The modelization of BLSD effects on bunch mass and greenlife should enable defining acceptable disease thresholds and optimizing bunch weight and harvest stage according to agronomic practices. On the other hand, fungicide use is conducive to significant environmental impact and must be limited. Forecasting strategies should be used wherever systemic fungicides are still efficient. Finally, the predominance of a unique type of susceptible cultivar is unsustainable and the recourse to resistant varieties in an integrated strategy is undoubtedly the future of BLSD control.

Introduction. Leaf area is often related to plant growth, development, physiology and yield. Many non-destructive models have been proposed for leaf area estimation of several plant genotypes, demonstrating that leaf length, leaf width and leaf area are closely correlated. Thus, the objective of our study was to develop a reliable model for leaf area estimation from linear measurements of leaf dimensions for citrus genotypes. Materials and methods. Leaves of citrus genotypes were harvested, and their dimensions (length, width and area) were measured. Values of leaf area were regressed against length, width, the square of length, the square of width and the product (length × width). The most accurate equations, either linear or second-order polynomial, were regressed again with a new data set; then the most reliable equation was defined. Results and discussion. The first analysis showed that the variables length, width and the square of length gave better results in second-order polynomial equations, while the linear equations were more suitable and accurate when the width and the product (length × width) were used. When these equations were regressed with the new data set, the coefficient of determination (R2) and the agreement index ‘d’ were higher for the one that used the variable product (length × width), while the Mean Absolute Percentage Error was lower. Conclusion. The product of the simple leaf dimensions (length × width) can provide a reliable and simple non-destructive model for leaf area estimation across citrus genotypes.

Introduction. Fruit green-life is a major postharvest attribute on which conservation on commodity chains depends. For climacteric fruits such as banana, green-life must be optimized to fit the transport and market requirements. Calcium was assumed to strengthen cellular tissue and increase the green-life of fruits. Materials and methods. In our study, we tested the effect of preharvest and postharvest calcium applications on attributes of banana fruit for two cultivars (Musa spp., AAA group, cv. Cavendish Grande Naine and Flhorban920 cultivar, AAA group). Results and discussion. Extra calcium in fertilization of Flhorban920 cv. did not significantly affect the green-life of fruits (36 days) or the hardness and thickness of the Flhorban920 cv. skin (63.7 N and 3.94 mm, respectively). The field calcium applications, by fertilization or spraying, did not alter pulp or peel chemical composition. For postharvest treatments, the green-life of Cavendish and Flhorban920 banana was not significantly altered by the presence or absence of calcium, or by the type of application, 45 and 26 days for the Cavendish and Flhorban920 cultivars, respectively.

L’arbre. Les arbres du genre Carapa (Meliaceae) sont présents dans toutes les forêts d’Afrique tropicale au niveau de l’équateur, du rift d’Albertine jusqu’au Sénégal et au Mali pour sa distribution la plus septentrionale. En Afrique comme en Amérique tropicale, le carapa est une source importante de Produits Forestiers ligneux (bois) et Non-Ligneux (PFNL). Le fruit et les graines. Le fruit typique de carapa est une capsule à quatre ou cinq valves qui renferment chacune deux à cinq graines, soit un total de huit à vingt graines par fruit. L’extraction de l’huile. Les villageois ramassent les graines tombées au sol avant qu’elles ne soient parasitées ou germées, ce qui est défavorable à la production d’une huile de qualité. L’extraction de l’huile se fait par ébouillantage des graines. L’huile extraite, polyvalente, est la substance issue de la plante qui est la plus utilisée devant les extraits de feuilles, d’écorce et de racines. Le marché. En Afrique, le commerce de l’huile de carapa est essentiellement local et reste une activité très marginale. Une demande accrue émane toutefois de l’utilisation de cette huile comme insecticide naturel dans la culture du coton biologique. Discussion. Compte tenu du potentiel économique de l’huile de carapa, sa commercialisation devrait respecter une rétribution équitable des paysannes afin de mieux rentabiliser la production. Des mesures de protection des arbres de carapa et de leur habitat doivent également être prises pour permettre une gestion de la production d’huile à long terme. La plantation semble être une option durable en vue de la conservation des peuplements naturels de carapa.

Introduction. The peel of bananas that ripen at ≥ 24 ℃ does not turn fully yellow, but retains a green colour, reducing the commercial value of the fruit. Historically, in experimental studies of this problem, fruit are ripened at constant temperatures; for example, either 20 ℃ or 30 ℃. In our experiments, we systematically varied the temperature of banana storage during ripening to investigate early events in ripening that may determine whether or not the peel remained green. Materials and methods. Fruits were exposed to temperatures of 20 ℃ or 30 ℃ for short periods before then storing at 30 ℃ or 20 ℃ to complete ripening. The L* a* b* colour system was used to measure change in green colour in the banana peel. Results. If the temperature of the fruit stored was 20 ℃ for the first few hours (≥ 14 h), then the peel became fully yellow, even in fruit subsequently ripened at 30 ℃. Conversely, if the temperature of the bananas stored was 30 ℃ for the first few hours of ripening, then full yellow colour was not obtained even if fruits were subsequently ripened at 20 ℃. Conclusion. The temperature of the first few hours of banana ripening determines whether or not the peel reaches full yellow colour.

Introduction. The conservation status of many wild fruit tree species that support rural people in Africa remains poorly documented despite its importance for their management. We compared the viability of tamarind (Tamarindus indica) populations, a dry land species that has nutritional, medicinal and cultural importance for rural communities, under different human-pressure levels. Materials and methods. The data relative to the tree diameter and height as well as the number of adults and stems were collected in plots of inventory and made it possible to calculate the dendrometric parameters for each targeted population, and to establish their diameter distribution. The dendrometric characteristics were analyzed by using nonparametric tests and the diameter distribution was adjusted to a truncated normal distribution. Results and discussion. Numbers of mature tamarind trees per hectare and regeneration (expressed as stem·ha–1) were relatively low, suggesting tamarind populations may not be self-rejuvenating. Nonetheless, significant variation occurred between habitat types (P < 0.001). Mature tree density in gallery forests [(18.2 ± 10.1) trees·ha–1] was three to eight times higher than that of savannah woodlands [(5 ± 4.5) trees·ha–1] and farmlands [(2.5 ± 0.4) trees·ha–1]. Young plants followed the same trend, with (11.2 ± 9.3) plants·ha–1, (1.1 ± 0.6) plants·ha–1, and 0.00 plants·ha–1, respectively. Diameter size class distributions departed from normality (P < 0.0001) and coefficient of skewness was positive irrespective of habitat type, indicating declining populations. However, median diameter values would suggest the species’ populations in farmlands and savannah woodlands to be more vulnerable than those occurring in gallery forests. These findings would suggest that gallery forests best suit tamarind in situ conservation. The observed severe reduction of trees and juveniles in farmlands and woodlands may negatively impact the long-term viability of tamarind populations. Juveniles’ introduction into farmlands may be needed to ensure conservation in agroforestry systems.

Introduction. Litchi has gained considerable economic importance in Mauritius as it is highly prized on the local and export markets for its size, colour and flavour, although no characterisation work has been performed so far. Materials and methods. In order to optimise litchi germplasm management in Mauritius, we evaluated 34 litchi accessions from three different agroclimatic regions. Phenotypic and morphological characters, and microsatellite markers were studied. Results and discussion. Phenological observations conducted over four consecutive fruiting cycles (2003/2004 to 2006/2007) showed that accessions could be grouped into early- and late-flowering cultivars, which initiated floral panicles from June to July and July to August, respectively. The harvesting season of litchi lasted from mid-November to mid-January with early-maturing cultivars being ready for harvest in the first month of the season. Phenological characters and fruit characterisation showed that the newly-introduced cultivar ‘Yook Ho Pow’ had a high commercial potential. Molecular studies using twelve pairs of SSR primers showed that, despite phenotypic variations among ‘Tai So’ genotypes in different locations (such as percentage of chicken-tongued seeds and leaflet size), the SSR profiles of leaf samples from all the studied ‘Tai So’ accessions were identical, suggesting that phenotypic differences could probably be attributed to environmental conditions rather than to genetic variations. Molecular characterisation revealed different cases of synonymies and homonymies in the genotypes studied.

Introduction. Among the citrus species, C. sinensis has been the most studied given its importance in terms of production and its industrial application in juices. Some of orange juice's organoleptic and functional properties, which make it an attractive product for the consumer, are due to its carotenoid composition. Xanthophylls can be found in either their free form (as the carotenes are found) or in a more stable fatty acid esterified form in the case of mono- and polyhydroxylated xanthophylls. Detection of adulteration of orange juices is of concern to consumers, regulatory agencies and citrus processing industries, and the study of carotenoid ester composition has been proposed to evaluate fruit products' authenticity. In this study, we report on the native (carotenoid esters and free carotenoids) carotenoid profile of orange juices of eight different varieties. Materials and methods. Monovarietal fresh orange juices were obtained from squeezing mid-season oranges (Citrus sinensis varieties: Bionda, Brasiliana, Moro, Ovale, Sanguinello, Tarocco, Valence and Washington) cultivated and supplied by a local producer. After the extraction of the carotenoids from the samples, the analyses were carried out by HPLC-DAD-APCI-MS. Results and discussion. The results showed that, in the juices studied, the xanthophylls were mostly esterified (93% of the total carotenoid mean content). The different varieties investigated showed variations in their carotenoid contents. The total carotenoid contents ranged from 2.42 µg·g–1 in the Washington variety to 15.8 µg·g–1 in the Valencia variety. Among the monoesters, the Valencia variety showed the highest violaxanthin ester amounts (61%), the Brasiliana variety showed the highest β-cryptoxanthin ester content (86.9%) and the Tarocco variety had the highest luteoxanthin ester amount (75.7%). Moreover, in general, in the Brasiliana, Ovale, Sanguinello, Valencia and Washington varieties, the monoester contents were higher than the diesters, whereas in the Bionda, Moro and Tarocco varieties the opposite was determined. To the best of our knowledge, this is the first time that this analytical approach has been applied to characterising, both qualitatively and quantitatively, the whole carotenoid pattern (carotenoid esters and free carotenoids) in orange juices from the Bionda , Brasiliana, Moro, Ovale, Sanguinello, Tarocco, Valence and Washington varieties. This contribution could also be used to establish authenticity markers among orange varieties that could potentially be used to prevent adulteration.

Introduction. The effects of imidacloprid and fenobucarb insecticides on the dynamics of the psyllid Diaphorina citri and on the incidence of Candidatus Liberibacter asiaticus (Ca. L. a.), the putative causal agent of Huanglongbing disease (HLB), were studied in a field experiment. Materials and methods. The experimental design consisted of three independent 0.5-ha Citrus orchards planted with disease-free HLB-susceptible orange trees, located in a Citrus producing area seriously affected by HLB. Imidacloprid was applied monthly to the trunks in one orchard at a rate of 0.15 g a.i.·tree–1; fenobucarb was sprayed fortnightly in a second orchard at a rate of 250 g a.i.·ha–1. The 3rd orchard was managed as a control without insecticide applications. The total number of adult D. citri specimens and the percentages of trees harbouring psyllid eggs and 5th instar nymphs were monitored at fortnightly intervals in each orchard. Ca. L. a. incidence was assessed in each orchard by PCR at 5 months, 12 months and 24 months after planting. Results. Compared with the control, both the fenobucarb and imidacloprid treatments reduced adult psyllid populations by over 90% and reduced the frequency of trees harbouring eggs and 5th instar nymphs. Only imidacloprid treatments totally prevented development of a new generation of adults from eggs. Two years after planting, the prevalence of Ca. L. a. was 0.939, 0.745 and 0.239 in the control and in the orchards treated with fenobucarb and imidacloprid, respectively. Discussion and conclusion. The results indicated that, although both the insecticides used effectively reduced D. citri populations by killing adults and nymphs and by affecting or preventing psyllid reproduction in orchards, neither of the two insecticide treatments totally prevented transmission of Ca. L. asiaticus. However, due to its long-lasting effect and systemic activity, the imidacloprid treatment provided the best protection against infections, and delayed and slowed down the spread of the pathogen. Furthermore, it reduced the number of pesticide applications needed and left the way open for biological integrated pest management programmes.

Introduction. Tamarindus indica est une espèce fruitière d’intérêt économique. Sa domestication au Sahel impose d’évaluer en préalable la variabilité de ses caractères phénotypiques sur l’ensemble de son aire de répartition. L’objectif de notre étude a été de caractériser différentes provenances de tamarinier à partir des caractères phénotypiques de leurs graines et plantules. Matériel et méthodes. L’étude menée en pépinière au Burkina Faso a porté sur l’étude des graines et germinations issues de neuf provenances dont deux d’Afrique de l’Est, deux d’Afrique de l’Ouest, deux d’Asie et trois de zones insulaires. Nous avons mesuré la longueur, la largeur, l’épaisseur et le poids de 100 graines de chaque provenance, et la hauteur, le diamètre au collet et le poids sec de la tige, ainsi que la longueur de la racine principale, le nombre de racines secondaires et le poids sec du système racinaire de 50 plantules âgées de 3 mois. Nous avons effectué une analyse de variance, puis une analyse en composantes principales sur les données centrées réduites de toutes les variables, enfin une classification hiérarchisée ascendante basée sur des indices de similarité. Résultats et discussion. Les différences entre variables ont été hautement significatives. Lors de l’étude des graines, nous avons obtenu un groupe lié à la provenance d’Inde et d’Afrique de l’Est, un autre lié aux provenances ouest-africaines et un groupe intermédiaire en provenance de Thaïlande. Lors de l’étude des plantules, il est apparu un groupe avec croissance aérienne forte et racine principale courte, fortement ramifiée et un groupe avec croissance aérienne faible, racine principale très longue, mais faiblement ramifiée. Le dendrogramme obtenu à partir des ressemblances phénotypiques (variables des graines et plantules) montre une structuration par aire géographique. Conclusion. La variabilité phénotypique inter provenance des plantules et des graines combinée aux corrélations entre variables pourrait permettre de sélectionner de façon précoce les provenances en fonction des objectifs définis pour la sélection.

Introduction. A study of accessions from the major production areas of Dacryodes edulis (Don) Lam. (Burseraceae) in Cameroon was carried out in order to assess the impact of pedoclimatic parameters and genetic factors on the characteristics and the classification of the fruits. The work focused on statistical analysis of fruit morphological and chemical parameters to distinguish accessions. Materials and methods. The fruits were collected from five localities of Cameroon (Obala, Boumyebel, Makenene, Njombe and Kekem). Twenty-six characters, among which were eleven quantitative morphological, nine qualitative morphological and six chemical characters, were the object of a correlation analysis, a principal component analysis and hierarchical classification. Results. Among the twenty-six characters studied, eighteen presented interesting morpho-chemical characters to discriminate the accessions. The fruit quantitative morphological characters were not significantly different, while the qualitative morphological and chemical characters showed significant differences for the localities concerned. A principal component analysis and hierarchical classification distinguished three major groups at a genetic distance of between 5.70 and 6.92: group I consists of accessions from Makenene and Kekem, discriminated by five characters (lipids, protein, grain colour, texture and colour of the mesocarp); group II consists of accessions from Njombe and Obala and was discriminated by six characters (weight of fruits, amino acids, sugars, phenols, epicarp colour and shape of grains); group III consists of the accession from Boumyebel and was discriminated by seven characters (fruit length and diameter; [fruit diameter / fruit length] ratio; weight of fruit, mesocarp and grain; and mesocarp thickness). Discussion and conclusion. Like agro-forestry species such as Ricinodendron heudelotii and Irvingia gabonensis, D. edulis presents intra-specific variations that are related to pedoclimatic conditions and genetic factors.