Introduction. In Cameroon, most subsistence farmers apply a mixed cropping system, resulting in a range of possible nematode host plants. Bananas and plantains (Musa spp.) are an important component of these cropping systems, both as a source of cash income and as a staple food. In order to program future extension projects, our study analyzed the cropping associations and their constraints in the West and Northwest provinces of Cameroon highlands. As nematodes have been identified as a major constraint to Musa production worldwide, we tried to assess the nematode presence. Materials and methods. A survey of over 200 households was done throughout the Cameroon highlands to identify the types of crop associations and preferences, management practices and pest awareness of small-scale farmers. In addition, samples were taken to examine the prevalence of Pratylenchus goodeyi on bananas and plantains in the home garden and one field of each household visited. Results and discussion. Cropping systems were highly variable between households, in so far as they could not easily be typified. Thirty-eight crops were identified planted in association with Musa spp. Bananas and plantains ranked as the most important crop for 43% of the farmers, followed by the staple crop maize (19%) and the traditional cash crop coffee (12%). Pest awareness (% awareness) was relatively high with respect to weevils (72%). The major constraints as perceived by the farmers related to leaf necrosis, weevils and nematode damage. Nevertheless, only 15% of them had heard of a nematode before. All root samples revealed nematode presence (over 40% showed more than 104 individuals·100 g–1 root fresh weight). P. goodeyi was the dominant species found.

Introduction. The causal agent of Panama disease in banana is Fusarium oxysporum f. sp. cubense (FOC). The authors put forward a hypothesis to account for certain disturbances of the natural defence mechanisms of banana plants against Panama disease as a consequence of very low Zn levels which could alter the mechanism of tylose formation. Materials and methods. A long-term experiment was carried out with 2-month-old banana plants in a growth chamber at 23 °C using three different levels of Zn nutrition. The nutrient solutions were inoculated with FOC 1 and FOC 4. Results and discussion. None of the total plants growing in a nutrient solution inoculated with FOC 1 showed infected rhizomes at the end of the experiment, but 75% of the plants growing in pots inoculated with FOC 4 had infected rhizomes. On the other hand, rhizome infection by FOC 4 was influenced by the nutrient solutions. The data showed that the number of plants with damaged rhizomes was significantly higher in the Zn-deficient treatments (100% of plants) than in the normal Zn solution (25% of plants), these internal symptoms being seen to worsen as the presence of Zn decreased in the nutrient solution. Conclusions. The results obtained seem to confirm the role played by Zn nutrition of banana plants in the appearance of Panama disease and are in accordance with our hypothesis concerning the relationships among plant Zn nutrition, plant IAA level, tylose formation and the incidence of the disease. Likewise, under our experimental conditions, race 1 of FOC is confirmed to be non-pathogenic against this banana cultivar, while race 4 is indeed pathogenic.

Introduction. Les agrumes sont sensibles à la salinité. Notre étude a cherché à sélectionner, chez le citrange Troyer, des lignées cellulaires tolérantes à NaCl, à évaluer l’effet du sel sur la croissance des cals et à doser les solutés susceptibles d’être impliqués dans leur réponse au stress salin. Matériel et méthodes. Des cals ont été cultivés sur un milieu de culture contenant du NaCl dont la concentration a été augmentée progressivement jusqu’à atteindre 8 g NaCl·L–1. Ils ont ensuite été transférés sur un milieu sans NaCl pour tester leur indépendance vis-à-vis du sel, puis remis en présence de 8 g NaCl·L–1 pour tester leur stabilité. Des dosages de solutés (Na+, K+, proline et sucres solubles) contenus dans les cals ont été effectués à la fin de l’expérimentation. Résultats et discussion. La salinité a ralenti la croissance et provoqué le brunissement de la plupart des explants (cals sensibles). Les cals tolérants ont présenté une croissance comparable à celle des témoins. Le transfert de ces cals sur un milieu sans NaCl suivi de leur remise en culture sur milieu salin a démontré l’indépendance et la stabilité du caractère de tolérance sélectionné. La teneur en K+ des cals tolérants a été voisine de celle des cals témoins, mais plus élevée que celle des cals sensibles. En revanche, la teneur en ions Na+ des cals tolérants et sensibles a été relativement plus élevée que celle des témoins. Le sodium s’accumulerait donc à deux niveaux cellulaires selon le type de cals : envahissement du cytosol (effet toxique) pour les cals sensibles ou compartimentage vacuolaire pour les cals tolérants. La salinité a provoqué l’accumulation de proline et de sucres solubles dans les cals tolérants mais pas dans les cals sensibles. Conclusions. Des lignées cellulaires stables et tolérantes au NaCl ont été obtenues à partir d’embryons de citrange Troyer. Cette tolérance pourrait être liée à des changements dans les propriétés de transport des ions et dans la capacité de régulation et de compartimentage ionique. L’accumulation de solutés organiques constitue un caractère métabolique à valeur adaptative qui pourrait être un indicateur de tolérance au stress salin des cals.

Introduction. In Mexico, the rambutan is not a well-known fruit tree, but it has great potential for its establishment and development in the Soconusco region because of the local good agro-ecological conditions for the production of its fruit. Currently, there are already 200 ha of plantations in the region with a good adaptation and a rewarding yield. Rambutan history, cultivation practices, post-harvest operation and commercialisation in the Soconusco region were studied to identify the possibilities of an expansion of the species. In particular, the work aimed at identifying different varieties inside the rambutan orchards. Materials and methods. Four areas were studied from a survey in 14 farms. Different parameters of fruit quality were analysed (ten trees sampled per farm): fruit diameter, fruit length, rind colour, spintern appearance, aril diameter, aril length, aril weight, flesh colour, flavour, succulence, adherence of flesh, and presence of pests and diseases. Results. Fruit quality was dissimilar for the four studied areas. Among the different fruit samples collected, it appeared that the environment and cultivation management play an important role in fruit size. The diversity of varieties planted in the different sites was determined by clustering analyses. Independent of their site of origin, at least six well-defined cluster classes could be identified. Conclusion. Fruit weight, spintern appearance and colour, as well as fruit diameter and aril to fruit weight appeared to be good indicators to identify fruit quality. The clustering analyses showed that there is a wide range of overlapping varieties to be found in the Soconusco region. Six major varietal groups were identified. Further varietal differentiation and characterisation of rambutan in the Soconusco region will be necessary for a better establishment of this fruit tree crop.

Introduction. R.heudelotii (Euphorbiaceae) est un arbre fruitier des forêts denses humides, exploité par les populations locales. L’espèce est dioïque. La régénération par graines actuellement utilisée n’est pas aisée et elle entraîne une hétérogénéité génétique des descendants. Jusqu’à présent, la multiplication végétative horticole a surtout été basée sur l’utilisation de plantules issues des graines. Le but principal de notre travail a été de développer une méthode de multiplication conforme in vitro d’arbres adultes de R. heudoletii sélectionnés. Matériel et méthodes. Les boutures de 2 cm (un œil + un bourgeon axillaire) ont été prélevées sur une plante adulte de R. heudelotii, puis mises en culture, après stérilisation, sur un milieu de Murashige et Skoog dilué de moitié. Différentes concentrations de kinétine ont été ajoutées à ce milieu de base (MB) pour étudier l’effet de cette cytokinine sur le débourrement et le développement des bourgeons axillaires. De même, les effets de la benzylaminopurine (BAP) ajoutée à MB ont été parallèlement étudiés sur la prolifération des bourgeons présents au niveau des nœuds des boutures. Enfin, l’enracinement des boutures après culture soit sur milieu avec kinétine, soit sur milieu avec BAP a été testé par repiquage des boutures sur MB enrichi en acide naphtalèneacétique (ANA). Résultats. La BAP à 4,5 mg·L–1 a permis la prolifération de 91 % des bourgeons présents au niveau des nœuds sur boutures avec un maximum de 4,8 bourgeons néoformés par bouture. Cependant, l’isolement de ces bourgeons sur milieu enrichi en ANA n’a pas permis d’observer la différentiation de racines. La kinétine à 2,5 mg·L–1 a favorisé le débourrement et le meilleur développement des bourgeons axillaires (71 %). Le repiquage sur MB + 2 mg ANA·L–1 a favorisé l’enracinement de 72 % des boutures mises en cultures au départ sur MB + kinétine, avec un maximum de 6,3 racines formées par bouture. Le taux de réussite de l’acclimatation des vitroplants régénérés a été de 52,7 %. Discussion et conclusion. En utilisant la kinétine et l’ANA, un maximum de 36 vitroplants enracinés de R. heudelotii ont été régénérés en 22 semaines à partir de 50 boutures mises en culture. Ce taux de multiplication reste faible et, pour une multiplication conforme efficace de l’espèce, il devra être amélioré par la production complémentaire de vitroplants à partir de la prolifération des bourgeons obtenus sur milieu avec BAP.

Introduction. Their physical and chemical properties make sandy tin tailings unsuitable for agricultural purposes without proper fertilizer and crop management practices. An attempt was made to use these tailings for sustainable production of pineapple using fertilization and irrigation techniques. Therefore, the objective of the study was to determine the effect of ground sucker size and levels of fertilizer used on yield and nutrient accumulation in plant components of pineapple cv. Josapine grown on sandy tin tailings. Materials and methods. Three fertilizer levels (plot 1, plot 2 and plot 3) containing N, P, K, Ca, Mg and Cu in solution and three classes of ground suckers (> 70 cm, 70–40 cm and < 70 cm) were used. They were arranged in a randomized complete block design with three replicates. There were 32 plants in each experimental plot. Each plot received a similar quantity of Fe, B, Mn, Zn and Mo. At harvest, each plant’s parts were divided into fruit, leaves, stem and roots. The dry matter yield and nutrient contents of each pineapple part were analyzed and recorded. Results and discussion. The highest and the lowest amounts of dry matter were 397 g·plant–1 (size > 70 cm) and 96 g·plant–1 (size < 70 cm), respectively. Total dry matter accumulation was greater (26%) for plot 1 than for plots 2 and 3. Substantial amounts of the dry matter accumulation occurred in leaves (45.0%) and fruit (34.0%) and less in stems (16.0%) and roots (5%). A similar pattern was also observed for the total (major and micro-) nutrient accumulation in the plant components. Besides the fruit parameters, the length of the pineapple stem is an important factor affecting the yield of pineapple, either expressed on a fresh (R2 = 0.904***) or dry (R2 = 0.855***) weight basis. Conclusion. Ground sucker size is a very important factor for successful production of a high fruit yield and quality of pineapple planted on sandy tin tailings.

Introduction. ‘Orange Red’ is an apricot cultivar released in the United States and characterised by large fruit of very good quality for both the fresh market and processing. For this reason, this cultivar is greatly appreciated in Europe, especially in France. However, its production is erratic under Mediterranean climate conditions. Materials and methods. The influence of two rootstocks (‘Manicot’ apricot and ‘GF31’ Myrobolan plum) on the productive behaviour of ‘Orange Red’ was studied under Mediterranean conditions in Murcia (Southeast Spain). Results and discussion. ‘Orange Red’ grafted onto ‘GF31’ Myrobolan flowered slightly later than those grafted onto ‘Manicot’ apricot. However, differences in the date of ripening of fruits were small. On the other hand, the percentage of flower bud retention and levels of floral fertility were higher when ‘Orange Red’ was grafted onto ‘GF31’ than onto ‘Manicot’, resulting in higher yields and fruits with a smaller weight. The increase in flower bud retention of ‘Orange Red’ grafted onto the rootstock ‘GF31’ was the main factor responsible for the increase in yield observed with this rootstock. Conclusion. Interaction between the cultivar and rootstock is presented as an interesting strategy for cultivar adaptation to different climatic areas.