ANANABIO: A project to design organic pineapple cropping systems through a participative approach between research and producers

ANANABIO is a multi-partnership project (2016-2018) associating Research (CIRAD) with a technical institute (ARMEFLHOR) on Reunion Island (Indian Ocean) to design innovative practices for environmental-friendly organic pineapple cropping systems. Other partners of the project are the local administrative support to farmers (Agriculture Chamber and agricultural training school), professional organizations of farmers and independent farmers as well. Pineapple produced under the French Organic production specifications are marketed with the label'Agriculture Biologique' (AB) of the French Ministry of Agriculture. The project proposes through a participatory approach to encourage farmers to co-design cropping systems with agronomists and to evaluate their performances. As far as cultural practices are concerned, ANANABIO focuses on the destruction of old crops and mechanized planting, organic fertilizer application, the pest and weeds management, and production of disease-free planting material. These cropping systems should also follow the Agroecology concept that promotes an agriculture that respects and protects man in his environment. (Résumé d'auteur

Considerations on growth characteristics of different pineapple varieties in Ivory Coast, Reunion Island and Caribbean Islands

Tendency in pineapple markets is to offer more and more varieties to the consumers as it is done for other products. Beside the references of 'Smooth Cayenne' and today 'MD-2' varieties, 'Queen' and new hybrids are also proposed for commercial production to the farmers. As consistency in production and quality is a key point for markets, it is important to know the behaviour of the different varieties at field level. Growth characteristics of 'MD-2', 'Smooth Cayenne' and 'Queen Victoria' have been assessed in different areas, such as on one hand in Côte d'Ivoire for 'Smooth Cayenne', 'MD-2', and on the other hand 'Queen Victoria' in La Reunion; additional data from Martinique have also been used for all varieties. Plant weight increases in a similar pattern for 'Smooth Cayenne', 'MD-2' and 'Flhoran 41', but is slower for the 'Queen' variety. 'D' leaves growth shows the classical sigmoid pattern for all the varieties. 'D' leaves weight is used as an index for forcing date determination. In Côte d'Ivoire on 'Smooth Cayenne' and 'MD-2', forcing is done when 'D' leaves reach 80 g fresh weight. At this stage plant weight is 2,0 kg and expected average fruit weight is 1.5 kg (standard for export). 'Flhoran 41' for the same plant weight, has a larger number of leaves and 'D' leaves weight is 75 g to harvest a fruit of 1.5 kg. 'Queen' shows a 'D' leaf weight of 50 g for a plant weight of 1.0 kg giving an average fruit weight of 700 g (air freight standard in La Reunion). The data give also a confirmation, if needed, that whatever the variety is, aerial suckers have faster growth than slips and the last ones have a faster growth than fruit crowns. A tentative growth model based on sum of temperature is proposed. It may be useful for determination of the date of forcing under standard growth conditions. (Texte intégral

Can systemic resistances contribute to ecologically based IPM control of nematodes in pineapple?

Pineapple monoculture and the use of pesticides reduced the biodiversity in the agrosystems and increased the imbalance between pathogenic and beneficial organisms. Non specific plant natural defenses may contribute to ecologically based IPM as an alternative to pesticides for nematode control in pineapple. Material and Methods: Two pineapple varieties, Smooth Cayenne (SC) and MD-2, received Elicitor treatment as soil applications of 50mL Methyl-jasmonate, 10-4 M, or Salicylic acid, 10-3 M, or Laminarin (? 1,3 Glucans), 37 g/L, followed by Nematodes inoculation: R. reniformis (5000/pot). Nematode populations growth was evaluated and enzymatic activities involved in plant defense: Catalase (CAT), Superoxide dismutase (SOD), Phenylalanine ammonialyase (PAL) and Lipoxigenase (LOX) were measured on non inoculated plants. Results: The nematode population growth was slowed down on the nematode tolerant variety MD-2 by Methyl-jasmonate and Salicylic acid, p values were 0.003, 0.021. Most of the decreases ranged 30 to 70%. Methyl-jasmonate and Laminarin induced significative enzymatic activities variations; Salicylic acid treatment did not. Most remarkable were the decreases of Catalase and PAL activities. Meanwhile LOX activity increased significantly and a slight increase in SOD was also observed. Discussion: Pineapple has been able to set up defenses against nematodes after elicitor treatments,but tolerant and sensitive varieties did not react equally. LOX, PAL and some of the oxidative enzymes (CAT) can be used to characterize the physiological changes in the plant. Is the MD-2 response a Systemic Resistance? Similar experiments using a split-root system have confirmed this (data to be published). LOXs control the Methyl-jasmonate pathway, meanwhile PAL controls the Salicylic acid and phenylpropanoids pathways. The LOX activity increase may reflect an enhanced biosynthesis of the signal molecule Methyl-jasmonate, characterizing an Induced Systemic Resistance set up. On the contrary, the decrease of PAL activity is less clear as it means less phenylpropanoids involved in plant defense. But it may also reflect a necessary balance between Salicylic acid and Methyl-jasmonate pathways. (Résumé d'auteur

Red alert on the plant-parasitic nematodes of banana

A mutant of 'Grande Naine', the cultivar MAI3 (Mt/sa AAA, Cavendish subgroup) has been selected in the field in Martinique for its good horticultural characteristics (hardiness, bunch conformation, productivity...). This peculiar cultivar always demonstrated significant lower susceptibilities to the bUlTOwing nematode Radopholus similis and to the lesion nematode Pratylenchus coffeae. In addition, the cv MAl3 exhibited singularly redder pseudostem as compared to others Cavendish clones. On the basis ofthese observations, we selected in field conditions some others 'coloured' mutants among different banana subgroups; cv MAl3_Green (Musa AAA, Cavendish subgroup), cv dwarfMossi_Green (Musa AAA, Red subgroup) and cvs 920_Red, 920_Green and 921_Red (Musa AAA, CIRAD hybrids). The susceptibility to nematodes of classic cultivars and associated mutants was evaluated under controlled conditions in a growth chamber on Andosol (volcanic ash soils representative of the French West Indies banana production area), at 24-28°C and 80% RH. Forty-five days after inoculation of each banana clone with 400 R. similis or P. coffeae per plant, the entire root system was carefully collected and weighted, and nematodes were extracted. In vitro micropropagation has no effect on the colour stability of the pseudostem. Reproductive factors and root infestations showed consistent trends, with an increase in R. similis root infestations for green mutants (up to 54%) and a decrease for red mutants (up to 61%) compared to classic cultivars. Surprisingly, the opposite consistent trend was observed for P. coffeae root infestations, with a decrease for green mutants (up to 43%) and an increase for red mutants (up to 76%) compared to classic cultivars. These results provide first evidence that colour criterion, representative of the anthocyanins content, could be a good and fairly simple indicator of nematode susceptibility in selection process. (Texte intégral

Effects of clay microstructure and compost quality on chlordecone retention in volcanic tropical soils: consequences on pesticide lability and plant contamination

The scientific and economic context of our study is related to the pollution of the soils, fresh and marine water by a persistent organochlorine pesticide (chlordecone) in a tropical context (French West Indies). The former application of chlordecone results today in a diffuse pollution in agricultural soils, which are sources of contamination for cultivated roots, tubers, vegetables and terrestrial and marine ecosystems. Chlordecone is a very though and stable molecule (considered as a POP), it is mainly present in solid phase and has a strong affinity with organic matters. To prevent consumers and ecosystems exposure, it is thus necessary for us to evaluate the factors that influence chlordecone migration in the environment. In our research, we studied the impacts of clay microstructure on the chlordecone retention, comparing allophanes (amorphous clays present in andosols) and halloysite clays (type 1/1). We showed that allophane aggregates had a greater ability to trap chlordecone mainly due to their fractal structure. We also measured the effects of added composts on soil microstructure and on chlordecone lability and transfer rate from soil to plant 3 and 6 months after incorporation. The intensity and persistence of these effects were related to the initial quality and richness of the added composts. (Résumé d'auteur

Soil microstructure and added organic matter: keys for chlordecone sequestration

The scientific and economic context of our study is related to the pollution of the soils, fresh and marine water by a persistent organochlorine pesticide (chlordecone) in a tropical context. The former application of chlordecone results today in a diffuse pollution in agricultural soils, which are sources of contamination for cultivated roots, tubers, vegetables and terrestrial and marine ecosystems. Chlordecone is a very though and stable molecule (considered as a POP), it is mainly present in solid phase and has a strong affinity with organic matters. To prevent consumers and ecosystems exposure, it is thus necessary for us to evaluate the factors that influence chlordecone migration in the environment. In our research, we studied the impacts of clay microstructure on the chlordecone retention. We showed that allophane aggregates had a great ability to trap chlordecone mainly due to their fractal structure. We also measured the effects of added composts on chlordecone lability and transfer rate from soil to plant . We show that compost addition modifies the fractal structure of allophane clays favouring the chlordecone retention. These results allow us to propose a new strategy in opposition to the complete soil decontamination: the chlordecone sequestration. ( Résumé d'auteur

A bait and trap method for sampling symphylid populations in pineapple

We developed a standardized method to monitor the Symphylids (Hanseniella sp) populations in pineapple using bait and traps. Two methods for symphylid extraction and counting were tested. Two statistical methods, the "variance/mean" ratio and a spatial analysis (Moran and Geary indices) were used to describe the type of spatial distribution of the populations. This bait and trap method allows a good evaluation of the symphylid populations. The ratio between adults and larvae may be used as an indicator of the population growth statute. Data collected on a rotation crop for pineapple, Mucuna pruriens var. utilis, showed that symphylids populations are highly aggregated following a negative binomial distribution. Finally, the method has been validated on MD2 pineapple plots to monitor the symphylids populations at different stages of development of the crop. (Texte intégral