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.

Diabetes mellitus is a global epidemic, characterised as a heterogeneous group of metabolic disorders associated with high risk of CVD. Green banana biomass, which is composed of resistant starches (RS) and cannot be hydrolysed by amylases, delays gastric emptying and modulates insulin sensitivity, thus contributing to improve metabolic disorders. The aim of the present study was to investigate the effects of consumption of RS from green banana biomass on body composition, fasting plasma glucose, glycated Hb (HbA1c) and homeostasis model assessment of insulin resistance in subjects with pre-diabetes or type 2 diabetes on top of treatment. Middle-aged subjects (n 113) of both sexes with pre-diabetes (HbA1c: 5·7–6·4 %) or diabetes (HbA1c ≥ 6·5 %) were randomised to receive nutritional support plus green banana biomass (40 g) (RS: approximately 4·5 g, G1, n 62) or diet alone (G2, n 51) for 24 weeks. Body composition, biochemical analyses and dietary intake were evaluated at the beginning and end of the study. In the experimental group (G1), consumption of RS was associated with reduction in HbA1c (P = 0·0001), fasting glucose (P = 0·021), diastolic blood pressure (P = 0·010), body weight (P = 0·002), BMI (P = 0·006), waist and hip circumferences (P < 0·01), fat mass percentage (P = 0·001) and increase in lean mass percentage (P = 0·011). In controls (G2), reductions were observed in waist and hip circumferences (P < 0·01), HbA1c (P = 0·002) and high-density lipoprotein-cholesterol (P = 0·020). In pre-diabetes or diabetes, non-significant differences were observed in the percentage reduction in HbA1c and fasting glucose in exploratory analyses. Our results indicate that the consumption of bioactive starches is a good dietary strategy to improve metabolic control and body composition.

Introduction. Black Leaf Streak Disease (BLSD) is the most important foliar disease affecting banana production worldwide. A forecasting system has been developed and implemented in various countries aiming at optimal control of BLSD through minimum applications of fungicide. In Dominican Republic, favorable dry climatic conditions contrast with serious organizational issues for BLSD control. Our objective was to evaluate the adaptation of this forecasting strategy in these specific conditions. Materials and methods. Fungicide resistance analyses were carried out in the northwestern region of Dominican Republic, in order to determine the appropriate spectrum of systemic fungicides for the forecasting strategy. Three field experiments were set up on commercial farms where disease evolution was monitored every week, on reference plots, in order to decide the pertinence of fungicide applications. Results. Fungicide resistance to QoI fungicides and strong sensitivity reduction to DMI (Demethylation Inhibitor) fungicides were detected in all farms. In spite of these limitations in the use of some fungicide groups, disease control was achieved with a limited number of fungicide applications (6–9), as compared with 13–26 applications in most commercial farms of Dominican Republic over the same period. Discussion. The calculation of an indicator of the efficiency of the chemical control confirmed the potential of the forecasting strategy, underlining the influence of crop management as well as the neighboring environment of the farms on its efficiency. The requirements for further generalization of this system to commercial farms of this country are discussed.

Musa argentii Gogoi & Borah (Musaceae), a new species, is described and illustrated from Lohit District, Arunachal Pradesh, India based on observed morphological characteristics in the field. Its distribution and habitat are described, and a key to the species is provided.

Abstract – Introduction. The susceptibility of banana fruit to crown rot andanthracnose, the two main banana post-harvest diseases, is influenced by many pre-harvestabiotic factors. Mycosphaerella leaf spot diseases (MLSD) of bananas arebiotic pre-harvest factors, which have an influence on fruit physiology. The fruit’ssusceptibility to post-harvest diseases may also be influenced by foliar diseases causedby M. fijiensis, responsible for black leaf streak disease (BLSD), andM. musicola, which causes sigatoka disease (SD). The aim of our studywas to determine the influence of these biotic pre-harvest factors on banana fruit’ssusceptibility to crown rot and anthracnose. Materials and methods. A diseaseseverity gradient was established in two experimental fields (Cameroon for BLSD andGuadeloupe for SD) where, at the flowering stage, six different levels of MLSD severitywere selected. Fruit susceptibility was determined through necrotic surface assessmentsafter artificial inoculation by Colletotrichum musae on the 3rd hand ofharvested bunches. Results and discussion. BLSD significantly influencedbanana sensitivity to crown rot (P < 0.001) but only had a slighteffect on the development of anthracnose ( P = 0.041). SD had no effect(P > 0.05) on banana susceptibility to either post-harvest disease.These results are discussed with emphasis on the influence of variations in thesource-sink ratio on fruit physiology. The influence of BLSD on crown rot disease suggeststhe need to take into account the management of these foliar diseases for an alternativecontrol method of post-harvest diseases through integrated pest management programs.

Introduction. Small-scale bananaproducers in Tanzania are facing constraints caused by the destructiveactivities of the banana weevil (Cosmopolites sordidus Germar).Many currently used methods of addressing the problem are ineffective ortoo expensive for local farmers to implement. Materials and methods.A combination of two integrated pest management (IPM) tools (regulartrapping in combination with field sanitation) was tested at twofarmer-managed sites (Bujela and Kyimo) and one researcher-managedsite (SUA-Morogoro). Treated areas were surrounded by untreatedcontrol areas where no trapping and limited sanitation was done.Changes in population densities were estimated by the mark-recaptureprocedure and the Lincoln index. Results and discussion. Aftereight months, weevil populations in the cleaned and trapped areashad been reduced by 33% (Bujela), 33% (Kyimo) and 74% (SUA). Thechange in population sizes in the control areas differed greatly,possibly due to discrepancies in field management between farmers’ andresearchers’ practice. Trap types, areas and sites affected thenumber of weevils captured. Disc-on-stump (DOS) traps captured moreweevils than corm disc (CD) and pseudostem (PS) traps. Weevils respondedmore strongly to traps in the clean area at SUA compared with theother two sites, probably because the more rigid sanitation practicesat SUA meant that volatiles from the traps were less likely to bemasked by volatiles from surrounding residues. Conclusion.Regular trapping with field sanitation can greatly reduce populationsof banana weevils, but strict adherence to method execution is requiredin order to gain favourable results.

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. Bananas and plantains (Musa spp.) are staple foods in Cameroon and surrounding countries. Strategies based on the utilization of cultural and locally consumed foods are essential for the identification of solutions for the reduction of micronutrient malnutrition. Materials and methods. To assess the nutritional content of some varieties in order to assist the selection of new Musa hybrids, the carotenoid contents of 19 Musa cultivars and hybrids from the CARBAP (Douala, Cameroon) germplasm were determined at three ripening stages. Frozen pulps were analyzed for their β-carotene, α-carotene and lutein contents using the HPLC method. The retinol activity equivalents (RAE)·100 g–1 fresh weight were calculated for four representative Musa types. Results and discussion. Significant differences were observed between Musa cultivars according to their genotype. Plantain type (Mbouroukou n°1) and Musa hybrid (CRBP 755) exhibited the highest levels of RAE [(148 and 70) RAE·100 g–1] compared with dessert bananas (16 RAE·100 g–1). During ripening, the concentrations of these carotenoids increased or decreased significantly (α = 0.05%) according to the Musa type analyzed. The high β- and α-carotene as well as lutein contents of these Musa sp. could contribute to the nutritional status of people consuming these banana varieties in West and Central Africa and enhance their use in Musa breeding programs.

Introduction. Wilt caused by Fusarium oxysporum f. sp. cubense (Foc) is the most important disease of banana worldwide, causing severe yield losses in commercial and local consumption cultivars. Chemical control is currently the most used method to manage the Fusarium wilt of banana, although it is toxic, expensive and dangerous. Therefore, control through genetic improvement is widely encouraged. Hence, breeding was carried out to develop banana hybrids with putative resistance. Materials and methods. Hybridization of identified resistant diploids with commercial triploids and tetraploids was carried out; it resulted in development of 22 hybrids with improved agronomic characters. In a second step, screening of these hybrids for resistance to Foc race 1 was attempted using the double cup method of challenge inoculation with the pathogen in the roots of the hybrids at optimum level. Host responses of the susceptible and resistant hybrids were examined under greenhouse conditions through biochemical and isozyme analysis. Results. Six hybrids among the 22 hybrids with improved agronomic characters were selected based on their yield and they were evaluated for resistance. Three of them were resistant to Foc and the others were susceptible. The resistance mechanism involving the relation of enzymes such as peroxidase (PO), polyphenol oxidase (PPO) and phenylalanine lyase (PAL), and biochemicals such as phenols, proline and lignin showed relatively higher activity in resistant hybrids and parents than susceptible ones. Isozyme analysis of PO and PPO carried out using selected resistant and susceptible hybrids revealed the induction of specific isoforms in the resistant hybrids upon challenge inoculation. Conclusion. Three hybrids were identified as potential hybrids with good yield and resistance to Foc race 1.

Introduction. Cucumber mosaic virus (CMV), genus Cucumovirus, is distributed worldwide; it is a common pathogen of Musa spp. and it is present in all banana-producing areas. Materials and methods. Banana and plantain (Musa) leaf tissues were collected from six major Musa-growing states of Southern Nigeria in August 2000. A broad-spectrum CMV polyclonal antibody was used in Protein A Sandwich (PAS) ELISA to detect CMV isolates, while a CMV subgroup I-specific polyclonal antibody was used in DAS-ELISA to separate subgroup I isolates. Results. Of 108 Musa leaf samples collected, 76 samples (70.4%) reacted positively with the CMV polyclonal antibodies used, in which 32 samples (42.1%) belonged to CMV subgroup I. Edo and Ondo states had low CMV subgroup I incidence of 13.6% and 17.2%, even though both states had high CMV incidence of 63.6% and 62.1% in infected samples, respectively. Imo state had the highest CMV incidence of 72.4% and subgroup I incidence of 55.2%. Of the 32 leaf samples infected with CMV subgroup I, 18 samples expressed one type of viral symptom such as interveinal chlorosis, chlorotic streaks, leaf puckering and crisp deformed leaf. Thirteen other samples expressed two or three viral symptoms, showing either vein thickening or general leaf chlorosis and any of the former symptoms. One asymptomatic leaf tissue was also infected with the virus. Discussion. Our results confirm that subgroup I and other subgroups are responsible for CMV infection in Musa species in Nigeria. The detection of CMV over a large geographical area underscores the importance of virus control measures. CMV can be controlled by use of virus-free suckers.

Introduction. A comparative study of antinutrients and heavy metals in the peels of five improved varieties of plantain and banana hybrids was investigated. Our aim was to provide information on plantain and banana peels that may circumvent huge losses during fruit processing by converting waste into wealth and health. Materials and methods. Four new plantain hybrids developed at the IITA, Nigeria, named PITA 14, PITA 17, PITA 24 and PITA 26, one cooking banana hybrid (BITA 3) and an African plantain landrace, Agbagba, were investigated. Antinutrient and heavy metal contents of the dried peels from the different cultivars were determined and the data were statistically analyzed. Results and discussion. The plantain hybrid PITA 14 differed significantly from other cultivars in saponin, tannin and oxalate. A significant difference was observed between PITA 17 in phytate compared with other cultivars. Cyanogenic glucosides found in PITA 17, PITA 26 and BITA 3 differed significantly from the values obtained in other cultivars. Both BITA 3 and Agbagba are significantly different from other cultivars in phenolic content, while PITA 24 and Agbagba differed significantly from other cultivars in lead. PITA 24 peels differed significantly from other cultivars in cadmium, but no significant difference was found among the different Musa varieties in mercury. Conclusion. In spite of the antinutritional properties ascribed to the various constituents investigated, the levels found in the peels of new Musa hybrids suggest that new varieties might not constitute a health hazard when ingested. Plantain and banana peels may be converted into livestock feeds, which will eventually provide protein and other nutrients to humans from consumption of meat and other products derived from the animals.

Introduction. Conventional evaluation of Musa through multilocation trials has often been carried out to ascertain the yield stability and ecological range of new varieties but, for prospective growers, it is equally important to know the fruit characteristics and ripening pattern of the genotypes. Indeed, fruit characteristics determine consumers’ attitudes towards the new varieties, and the associated market value of these varieties. Materials and methods. The metric traits and ripening pattern of fruits from nine Musa hybrids and one local variety of plantain were evaluated during two cropping seasons in a sub-humid environment in Nigeria. Results. All the traits measured varied with the genotype, but cropping cycle influenced only fruit weight and days to complete senescence of fruits. The interaction between genotype and cropping cycle was significant on fruit weight, fruit length and days to attain four different ripening stages. Most genotypes had better values in the ratoon harvest than in the plant crop. Fruit length and shape of PITA 21 were comparable with those of the local check, but the index of edible proportion was highest in PITA 22. PITA 21 and PITA 26 had the longest green life and total shelf life. Conclusion. The genotypes evaluated in our study revealed different utilization potentials. Also, the better postharvest life of some of the hybrids and comparable metric traits with the local check suggested the high adoption potential of the hybrids.

Introduction. Chips or crisps are the most important foods usually fried; they are presented in the form of thin discs (chips) or sometimes in the form of sticks (French fries). Materials and methods. Chips were prepared starting from pulp samples resulting from five hybrids of plantain and banana newly released in Nigeria and from a local cultivar used as reference. The iron, zinc and pro-vitamin A contents were investigated in the chips to unveil their micronutrient content. Results and discussion. The results showed that there was no significant difference (p < 0.05) in the iron content of the chips produced from the new plantain and banana hybrids, while a significant difference (p < 0.05) existed in both zinc and total carotenoid contents of the hybrids. Chips made from BITA 3, a hybrid cooking banana, couldcontribute 2.61 retinol equivalent (RE)e [1 (RE)e = 6 µg β-carotene (precursor of vitamin A)] daily, if a small packet of chips (45 g) is consumed, based on the Recommended Daily Dietary Allowance. A 45-g packet of chips made from PITA 26 can contribute 14.6% and 20.1% of the daily requirements of zinc per day, and 30.1% and 22.3% of the requirements of iron per day, for a man and a woman, respectively. Conclusions. The new plantain and banana hybrids may therefore significantly participate in a food strategy aiming at combating the lack of micronutrients in the sub-Saharan African diet.

Introduction. Bananas are traditionally propagated by suckers: nevertheless, the advantage of using tissue-cultured plants for banana production has been demonstrated in recent years. Despite the large-scale use of micropropagated plants in the subtropical regions, little information is available on the performance of these crops in tropical countries. So we compared the yield potential of some Cavendish banana cultivars propagated either by traditional suckers or by tissue culture. Materials and methods. A randomized complete block experiment was established in a commercial plantation in Cameroon to compare the performance of three tissue-cultured banana plants of Grand Nain, Williams and Zelig cultivars and two conventionally-propagated plants of Grand Nain and Williams. Morphological, phenological and yield component data were collected for six crop cycles. Results. All the plants grew vigorously and produced quality exportable fruits. However, the tissue-cultured plants consistently produced heavier bunches and higher yields than the conventionally-propagated plants. The highest yields (65.92 t·ha–1 for Grand Nain, 64.60 t·ha–1 for Williams and 65.58 t·ha–1 for Zelig) were obtained for the tissue-cultured plants in the third crop cycle compared with 51.43 t·ha–1 and 59.02 t·ha–1 obtained for the traditionally-propagated Grand Nain and Williams plants, respectively. There were no significant yield differences between the plants of different origin in the second and fourth cycles, respectively. However, the tissue-cultured Williams and Zelig plants outperformed the other plants in the sixth crop cycle. Conclusion. The tissue-cultured plants of the three Cavendish cultivars studied performed better than the plants resulting from conventional suckers. The best cultivar for commercial plantation used, that is located in a tropical environment, was Williams. In general, to obtain an optimum benefit, we would recommend the use of tissue-cultured plants over a period of 6–7 years with good management practices.

Introduction. Many shoots or bud-like structures are lost in the final stage of plant micropropagation because of being too short for handling. Yellow and red lights induce in vitro plant growth of some species, and blue light reduces it instead. Yellow cellophane film passes through from the yellow to red light spectrum but cuts off the blue one. Growth of banana in vitro shoots was thus compared with or without yellow-cellophane-film shading. Materials and methods. Field-grown banana normal and dwarf variant plants of Nanicão cv. (Musa sp., AAA group, Cavendish subgroup) derived from micropropagation were re-established in vitro. They were then transferred to MS medium without growth regulator in test tubes covered by yellow cellophane film under cool white fluorescent lamps at a light intensity of 46 μmol·m–2·s–1. Shoot growth was measured as height was evaluated after (20 and 30) days of culture. Results and discussion. The yellow-cellophane-film shading stimulated the growth of banana in vitro shoots. When cultured under the yellow-cellophane-film shading for 20 days, the normal true-to-type plants showed an increase of about 25% in shoot height compared with the plants cultured without cellophane film. Similar growth response was also observed on the in vitro shoots of the dwarf plants but the increment was only about 12%. This shading technique can aid shoot elongation and consequently reduction of plantlet loss at the final stage of plant micropropagation. The differing sensibility of the normal true-to-type plants and dwarf variants to the yellow-cellophane-film shading may be used for reduction of the dwarf variant population in banana micropropagation. Conclusion. Yellow-cellophane-film shading stimulates growth of banana in vitro shoots.

Introduction. The worldwide production of banana and plantain, which is estimated to 106 Mt·year–1, relies on a narrow genetic basis. Thus, banana production is fragile regarding emergent diseases, and creation of new varieties of banana stands out as a real necessity for its sustainability. In banana, various improvement strategies aim to create triploid hybrids. The objective of this report is to present a simple in vitro methodology to induce stable tetraploid plants by colchicine treatment, usable as parent for obtaining triploid varieties. Materials and methods. Twenty-one diploid M. acuminata clones and three interspecific M. acuminata / M. balbisiana diploid clones were treated as proliferating culture in liquid medium with 1.25 mM of colchicine for 48 h. Plant screening has been performed by morphological identification in greenhouse, chromosome counts on root tips and flow cytometry on leave blades on vitroplants using propidium iodide staining. Results. Chromosome counts led to distinguish diploid and tetraploid plants but did not afford to detect chimeras. Flow cytometry allowed an early screening of a larger number of plants leading to detect rapidly chimerical plants. It was observed that some stable 2x / 4x cytochimeras are periclinal. Tetraploid clones were obtained with all diploid genotypes. General behaviour of tetraploids in the field was globally weaker than the corresponding diploids. Nevertheless, all the doubled-diploids flowered and crossed with diploid plants to obtain triploid progenies. Conclusion. This study has clearly shown that induction of stable doubled-diploid plants can be obtained from a wide range of genetically different bananas. These results open the way to the systematic use of doubled-diploids by banana breeding programs for the release of enhanced triploid varieties.

Introduction. A study was conducted in India to assess the efficiency of 32P uptake and the feasibility of intercropping using land-use efficiency parameters in a banana-based intercropping system. Materials and methods. Absorption of 32P applied to plants in five-crop, two-crop and sole-crop systems involving banana Musa AAB (‘Mysore’), ginger (Zingiber officinalis Rosc.), turmeric (Curcuma longa L.), cassava (Manihot esculenta Crantz.) and elephant yam (Amorphophallus campanulatus Blume.) was studied in field trials. The experiment was conducted for two years. During the first year, the main crop was planted during October, the main planting season for banana in India, and the intercrops were planted in early May of the next year. In the second year, both the main crop and intercrops were planted in May. Results. Radiophosphorus applied in the active root zone of one of the component species in the mixed crop system was found to be absorbed not only by the treated plant but also by the neighboring plants. Absorption by banana was prevalent. Differential effects of competition were manifested as observed by the relative uptake of 32P. Lower relative uptake of 32P was observed in the main crop banana when simultaneous planting of intercrops was done. Ginger and turmeric were not affected in relation to planting at different stages of the main crop, whereas cassava and elephant yam showed lesser relative 32P uptake when planted later, confirming that different crops in the mixed crop system react differently. Conclusions. The efficiency of different crops in terms of uptake varied with the system of planting. The higher relative efficiency of 32P uptake in a multiple cropping system points to an improved efficiency of uptake and higher dry weight on a per plant basis. It confirms the efficiency and feasibility of the cropping system. Economic analysis emphasizes the concept and proves the viability of the system.

Introduction. Competition between plants on a mat (intramat) and between plants on different clumps (intermat) is quite common in crops such as banana. A study was therefore undertaken to know the extent of intramat and intermat competition using isotopic techniques. Materials and methods. The competition between plants in a mat and between mats were recorded in a combination of three spacings and five physiological phases of sucker retention by giving 32P to an experimental plant using soil injection techniques and monitoring the levels of recovery. The recovery of the isotope was recorded in the applied plant and its daughter (intramat) and in the neighboring border plant and its sucker (intermat). Results. The study revealed that, when 32P was given by soil injection techniques to one plant, it could be recovered in the border plant and its sucker during both years of study. In the first year, activity in initial samplings in border clumps were the highest, with the widest spacing in the experimental plant showing the highest recovery, but a differential pattern of recovery was observed at different samplings in the border clumps. In the irrigated crop of the second year, the highest recovery was observed at the closest spacing in both the experimental and border clumps. With respect to sucker retention at definite physiological phases, the recovery was the highest at the late vegetative phase, the flower bud initiation and the shooting phase. The recovery in the mother plant and its sucker and the border plant and its sucker studied separately gave a measurement of the intramat competition. Conclusion. The differential nature seen with retention phases confirms the requirement and intensity of activity with defined physiological phases and the overall need to evaluate and redefine recommendations, taking into consideration the critical physiological phases.

Introduction. Aux Antilles, l’introduction de la jachère, dont l’utilité dans la maîtrise du parasitisme tellurique est avérée, est à l’ordre du jour du fait de l’explosion du parasitisme lié à la monoculture bananière. Comme cette pratique est soutenue par la recherche et les pouvoirs publics, l’étude entreprise a eu pour but d’analyser les écarts entre les préconisations portées par un dispositif institutionnel et les pratiques des agriculteurs afin d’identifier à quelles conditions les pratiques de jachère peuvent être mises en place. Méthodologie. Les déterminants et fonctions attribués aux jachères ainsi que les freins ont été abordés à partir d’enquêtes auprès d’exploitants. Celles-ci ont permis de recueillir entre autres les variables nécessaires à la caractérisation des règles de décision en matière de gestion des assolements et de contraintes endogènes à l’exploitation. Le choix des exploitations enquêtées nous a conduits à étudier les pratiques de jachères dans le cadre d’une typologie d’exploitation distinguant, parmi 42 exploitations étudiées, les types, « Diversifié », « Bananier familial » et « Bananier entrepreneurial ». Ces types sont représentatifs des exploitations de moins de 20 ha. Le cas de la jachère en Guadeloupe. Les résultats ont montré que la jachère est présente chez plus de la moitié des exploitants enquêtés. Sa situation varie avec les types d’exploitation ; elle est soit subie, soit intégrée dans les systèmes de culture. Les modes de conduites sont fonctions des objectifs des exploitants : assainissement, pâturage, gestion de la trésorerie, etc. Les freins au développement des jachères sont nombreux : manque de surface, difficulté de raisonner à long terme, manque à gagner sur une terre qui ne « produit » pas, etc. Cependant les calculs économiques sur des systèmes de culture incluant la jachère montrent que leurs marges brutes sont supérieures à celles trouvées pour des bananeraies continues et pérennes. La principale contrainte est rencontrée au moment du changement de système cultural lorsque l’exploitant doit faire face à une terre qui ne procurera un supplément de rendement que deux ans plus tard. Discussion et conclusion. Notre étude a mis en évidence que la multiplicité des pratiques de jachère, pertinentes au regard des objectifs des exploitants, n’est qu’en partie prise en compte dans les dispositifs institutionnels existants. Cela appelle une diversification des référentiels techniques.

Introduction. A study was done to compare Gruesa, a local dwarf Cavendish selection, with two other cultivars of the Cavendish subgroup in the open air or under greenhouse conditions in two localities of the Canary Islands. Materials and methods. The trials were set up with the cultivars Zelig, Grande Naine and Gruesa in four plots on the northern slope: one outdoors and three under three different greenhouse covers (one with polyethylene lamina and the other two with different types of mesh), and in one outdoor plot on the southern slope of the island of Tenerife. Morphological, phenological and production characteristics were studied over three productive cycles. Results. Significant differences were found in both plant height (Grande Naine > Zelig > Gruesa) and pseudostem thickness (Gruesa > Grande Naine = Zelig). Each cultivar showed a stable [height:thickness] ratio, remaining the same in all trial conditions. Gruesa cycle length was longer than those of the other two cultivars, emitting more leaves until bunch emergency. Gruesa produced the most hands per bunch and the most fingers per hand. In all cultivars, finger length was directly related to pseudostem height. All three cultivars produced well, with fruits very similar in organoleptic traits. A reduction in cycle length and a slight increase in productivity were observed in the northern plot under the polyethylene cover compared with the plots under other covers and outdoors. Conclusion. Gruesa appears more recommendable than Zelig and Grande Naine for open-air plantations in windy localities.