Léifi NODICHAO - Academia.edu (original) (raw)
Papers by Léifi NODICHAO
Philosophical Transactions of the Royal Society of London. B, Biological Sciences, 1988
The various patterns of environmental sex determination in squamates, chelonians and crocodilians... more The various patterns of environmental sex determination in squamates, chelonians and crocodilians are described. High temperatures produce males in lizards and crocodiles but females in chelonians. Original experiments on the effects of incubation at 30 °C (100% females) or 33 °C (100% males) on development inAlligator mississippiensisare described. These include an investigation of the effect of exposing embryos briefly to a different incubation temperature on the sex ratio at hatching, and a study of the effects of 30 °C and 33 °C on growth and development of alligator embryos and gonads. A 7-day pulse of one temperature on the background of another was insufficient to alter the sex ratio dramatically. Incubation at 33 °C increased the rate of growth and development of alligator embryos. In particular, differentiation of the gonad at 33 °C was enhanced compared with 30 °C. A hypothesis is developed to explain the mechanism of temperature-dependent sex determination (TSD) in crocod...
![Research paper thumbnail of Empirical prediction accuracy of genomic selection between experimental designs and generations in oil palm. [W667]](https://attachments.academia-assets.com/120079222/thumbnails/1.jpg)
](Plant and Animal Genome XXIV Conference, Jan 10, 2016
Annals of Botany, Jun 28, 2011
† Background The African oil palm (Elaeis guineensis) is a monoecious species of the palm subfami... more † Background The African oil palm (Elaeis guineensis) is a monoecious species of the palm subfamily Arecoideae. It may be qualified as 'temporally dioecious' in that it produces functionally unisexual male and female inflorescences in an alternating cycle on the same plant, resulting in an allogamous mode of reproduction. The 'sex ratio' of an oil palm stand is influenced by both genetic and environmental factors. In particular, the enhancement of male inflorescence production in response to water stress has been well documented. † Scope This paper presents a review of our current understanding of the sex determination process in oil palm and discusses possible insights that can be gained from other species. Although some informative phenological studies have been carried out, nothing is as yet known about the genetic basis of sex determination in oil palm, nor the mechanisms by which this process is regulated. Nevertheless new genomics-based techniques, when combined with field studies and biochemical and molecular cytological-based approaches, should provide a new understanding of the complex processes governing oil palm sex determination in the foreseeable future. Current hypotheses and strategies for future research are discussed.
Cereal Research Communications, Dec 1, 2010
Literature confirms that using polyethylene glycol (PEG) as an osmotic agent to imitate water sho... more Literature confirms that using polyethylene glycol (PEG) as an osmotic agent to imitate water shortage was not so easy in practice, due to PEG toxicity effects and frequent contaminations. Two new approaches were developed to alleviate those problems, one using a raft covered with a membrane to prevent PEG entry in roots, and one using solidified PEG media. The raft trials were done on corn, hexaploid and tetraploid wheat, rye, triticale, oats, barley, Agrotricum; those in solid media, with corn, hexaploid and tetraploid wheat, barley, sorghum and pearl millet. Different species respond differently to PEG-induced osmotic stress. In our trials, the most sensitive cereal was corn, and this finding correlates with the lower osmotic pressure of the sap (a constitutive trait in corn seedlings). Corn responded to osmotic stress by a very poor rate of elongation of the coleoptile, especially when the highest stress (32% PEG) was used. This behavior was also observed in the field in dry years, for example in the Sahel area. Compared to this sensitive cereal species, all other cereals tested were more resistant. Hexaploid and tetraploid wheat, triticale, and Agrotricum kept capacity to elongate roots when submitted to a high osmotic stress, but the higher stress reduced root length considerably. Barley kept rooting ability like other cereals, but was able to develop more aerial biomass, seminal roots, and ramifications. Barley root hair was also longer and covered a higher proportion of the root. Those adaptive features likely explain part of the good adaptation of barley to dry Mediterranean areas. Preliminary results on solid media also showed relationships between drought resistance and the osmoresistance response, at least when comparing species. Roots of species adapted to hot climate, like pearl millet and sorghum, had few seminal roots but displayed a strong gravitropism under osmotic stress. The ease of use of solidified PEG media shows promise for future larger scale trials. Applications of solidified PEG media for research beyond cereal crops is envisioned.
Journal of insect science, 2015
The edibility of different Elaeis sp. breeding populations present in Benin was tested for the le... more The edibility of different Elaeis sp. breeding populations present in Benin was tested for the leaf miner Coelaenomenodera lameensis Berti (Coleoptera: Chrysomelidae), a major oil palm pest in Africa. Experiments carried out in sleeves revealed the oviposition capacities of females and the mortality rates for the different developmental stages by comparing the populations found on two breeding populations of Elaeis oleifera (HBK) Cortes, four of Elaeis guineensis Jacquin and four (E. guineensis  E. oleifera)  E. guineensis backcrosses. Females laid their eggs similarly on all breeding populations, with a preference for the E. guineensis La Mé origin. The average hatching rate reached 80% for the La Mé origin as opposed to 28% for the Deli origin. The mortality rates for the larval instars were greater on E. oleifera, on certain backcrosses and on the Deli origin of E. guineensis. Development at the second-and third-larval instars was the most affected, with a mortality rate of three to five times greater than that seen on La Mé. Epidermis and cuticle measurements indicated which breeding populations were suitable or unsuitable for the development of C. lameensis. E. guineensis, with its thin epidermis (12 mm) and cuticle (2 mm), proved to be highly susceptible to C. lameensis attacks. On the other hand, E. oleifera, which is very resistant, exhibited a thicker epidermis (17 mm) and cuticle (4 mm). The breeding populations were thus classified according to the positive or negative influence they exerted on the insect's egg laying and feeding. RÉSUMÉ. La comestibilité de différents matériels végétaux d'Elaeis sp. présents au Bénin est testée pour Coelaenomenodera lameensis Berti (Coleoptera: Chrysomelidae), important ravageur du palmier à huile en Afrique. Des expérimentations en manchons ont permis de déterminer les capacités d'oviposition des femelles et les taux de mortalité des différents stades de développement (oeufs, larves, nymphes et adultes) en comparant les populations observées sur deux origines d'Elaeis oleifera (HBK) Cortes, quatre origines d'Elaeis guineensis Jacquin et quatre Backcross (E. guineensis  E. oleifera)  E. guineensis. Les femelles pondent indifféremment sur tous les types de matériel végétal avec une préférence pour l'origine La Mé d'E. guineensis. Le taux moyen d'éclosion atteint 80% pour l'origine La Mé contre 28% pour l'origine Deli. Le taux de mortalité des stades larvaires est plus important sur E. oleifera, sur certains Backcross et sur l'origine Deli d'E. guineensis. Le développement des deuxiè me et troisiè me stades larvaires sont les plus affectés avec un taux de mortalité 3 à 5 fois supérieur à celui observé sur La Mé. Des mesures d'épiderme et de cuticule mettent en évidence l'existence de matériel végétal favorable ou défavorable au développement de C. lameensis. E. guineensis dont l'épiderme (12 mm) et la cuticule (2 mm) sont peu épais se révèle être trè s sensible aux attaques de C. lameensis. Au contraire, E. oleifera présente un épiderme (17 mm) et une cuticule (4 mm) plus épais et est très résistants. Le matériel végétal est ainsi classé suivant l'influence positive ou négative qu'ils exercent sur la ponte et l'alimentation des insectes.
Journal of Applied Biosciences, May 13, 2019
Objectives: Fusarium wilt is the first oil palm pathology, who devastates the plantations in Afri... more Objectives: Fusarium wilt is the first oil palm pathology, who devastates the plantations in Africa. The currents study aims to diagnose the spatial distribution of this pathology and the incidence of the disease caused by Fusarium oxysporum elaeidis (Foe) in the palm oil growing zone of Benin. Methodology and Results: Thus, a survey was carried out in May 2018 covering 16 plantations distributed in four agroecological zones of production of palm oil in Benin. In each plantation, 15 plants were randomly inspected to evaluate the incidence, the severity, and the distribution of the disease. Root and soil samples were collected at the foot of each evaluated tree, at a depth of 20 cm using an auger. Samples were stored in polyetilene bags, for the detection and isolation of the pathogenic agent. The results showed that incidence is significantly different depending on the agroecological zones prospected (p=0.000). Central Cotton Zone (Kétou) and the Fisheries Zone (Adjohoun) recorded an incidence of vascular wilt of 0%, whereas on the sites surveyed in the Depression Zone (Pobè, Adja-Ouèrè) and the Bar Land Zone (Ifangni, Missérété, Sakété, Adjarra) the recorded disease incidences were 30.0% and 12.5%, respectively. This study also revealed an uneven distribution of the pathogen on the sites surveyed. Indeed, the study of the soil samples taken at the foot of the plants revealed that the presence of Foe does not systematically induce the disease, or induces it to varying levels, although the isolate is pathogenic and the material planted on each site is identical. Conclusions and application of results: These results demonstrate a polymorphism of oil palm susceptibility to Fusarium wilt and underline the need to define a new screening approach based on the susceptibility factors of oil palm and which minimizes the intra-crossing variations observed.
Journal of Applied Biosciences, 2019
Importance des manifestations des symptômes de déficience minérale du palmier à huile (Elaeis gui... more Importance des manifestations des symptômes de déficience minérale du palmier à huile (Elaeis guineensis Jacq.) dans les plantations paysannes au Sud-Bénin en Afrique de l'Ouest
European Network of Palm Scientists, 2018
BASE, 2017
Introduction. L’acidification de l’huile de palme détermine la qualité et la stabilité de cette i... more Introduction. L’acidification de l’huile de palme détermine la qualité et la stabilité de cette importante denrée alimentaire. Cette synthèse analyse les causes de l’acidification de l’huile et son impact sur la qualité et la stabilité de l’huile. Les enjeux liés à la réduction de l'acidification de l'huile et les approches utilisées sont aussi analysés, en particulier la réduction par l’amélioration génétique. Littérature. L'acidification est principalement due à l’action de la lipase endogène du mésocarpe, mais peut aussi être causée par des lipases microbiennes ou une hydrolyse autocatalytique. Plusieurs facteurs, notamment le matériel végétal, les conditions de récolte et de traitement post-récolte des régimes, d’extraction et de conservation de l’huile impactent de manière significative l’acidification de l'huile. L’acidification réduit la qualité et la valeur marchande de l’huile et engendre une baisse de productivité. Des fonds génétiques à faible acidité ont ...
Plants, 2022
Sexual differentiation of inflorescences and flowers is important for reproduction and affects cr... more Sexual differentiation of inflorescences and flowers is important for reproduction and affects crop plant productivity. We report here on a molecular study of the process of sexual differentiation in the immature inflorescence of oil palm (Elaeis guineensis). This species is monoecious and exhibits gender diphasy, producing male and female inflorescences separately on the same plant in alternation. Three main approaches were used: small RNA-seq to characterise and study the expression of miRNA genes; RNA-seq to monitor mRNA accumulation patterns; hormone quantification to assess the role of cytokinins and auxins in inflorescence differentiation. Our study allowed the characterisation of 30 previously unreported palm MIRNA genes. In differential gene and miRNA expression studies, we identified a number of key developmental genes and miRNA-mRNA target modules previously described in relation to their developmental regulatory role in the cereal panicle, notably the miR156/529/535-SQUAM...
Plant and Soil, 2021
Background and aims Root biomass is one of the most widely used parameters to characterise root g... more Background and aims Root biomass is one of the most widely used parameters to characterise root growth and belowground carbon stock. Our aim was to define a standard method to estimate the root biomass of young and adult oil palm trees in commercial plantations. Methods Three methods based on the sampling excavation volume were compared using the same sampled tree. Work time and the number of workers required for each operation were recorded. We compared two large excavation volumes based on Voronoi tessellation and the standard root auger coring method in one 2year-old and one 16-year-old commercial oil-palm plantation in Benin, West Africa. Results Oil palm total root biomass was estimated at 0.84 and 22.23 Mg ha −1 in the 2-year-old and 16-yearold plantation, respectively. Compared to the reference method, the simplified Voronoi trench method estimated slightly higher (+5%) and lower (−17%) total root biomass with no significant differences but required 2 and 3 times more labour time, respectively, while the auger method estimated significantly lower (−23% and − 53%) total root biomass in the 2-year-old and 16-yearold plantation, respectively. Coarse and fine root biomass were significantly higher under the windrow than under the footpath zones. Conclusion The simplified Voronoi trench method required twice as much labour time as the auger method but was most efficient way to estimate oil palm total root biomass, irrespective of the age of the plantation.
Good management practice in oil palm rely on accurate predictions of fertiliser require-ments tha... more Good management practice in oil palm rely on accurate predictions of fertiliser require-ments that respect the environment and are economically optimal. A study performed in Indonesia pointed out that K and Mg leaf contents greatly vary from one oil palm progeny to another for the same production level. Such differences in nutrient contents may lead to an incorrect assessment of the nutrient requirements, questioning the validity of leaf analysis as a diagnostic tool and raise several research questions: Do oil palm progenies with different leaf nutrient contents need to be fertilised with specifics fertilisation tables? Does the difference in leaf nutrient contents between progenies reflect different patterns for nutrient allocation within plant tissues? Do mineral absorption and fertiliser recovery eyciency differ according to oil palm progenies? and to what extend so far? Is there any progeny which can adapt itself to agronomic practices requiring less fertiliser for highest prod...
![Research paper thumbnail of Empirical prediction accuracy of genomic selection between experimental designs and generations in oil palm. [W667]](https://attachments.academia-assets.com/116634708/thumbnails/1.jpg)
](There is still a large potential for the genetic improvement of yield in oil palm, as it has only... more There is still a large potential for the genetic improvement of yield in oil palm, as it has only been submitted to a few generations of modern breeding. Selection candidates are traditionally evaluated in progeny tests, as some yield components have a low heritability. The progeny-tests allow selecting with a high accuracy, but constrain the rate of genetic gain as they increase the generation interval and limit the number of evaluated individuals. Genomic selection (GS) is an appealing alternative to the current phenotypic selection, as it could allow selecting without progeny tests. Here, we studied the prediction accuracy of GS in the two heterotic groups used to produce oil palm commercial hybrids, ie the correlation between the genomic estimated breeding values and the breeding values obtained from the conventional method of phenotypic selection. We used two independent experimental designs located in Sumatra (Indonesia), comprising over 700 hybrid crosses. The GS model was ca...
Root biomass is one of the most used parameter to characterise root development and distribution ... more Root biomass is one of the most used parameter to characterise root development and distribution within soil. However, different methods exist with regards to plant root system architecture, soil sampling volume and planting design but no standard protocol were set up for Monocotyledonous trees in an equilateral triangle planting design and comparing different ages of plantation. The purpose of this work was to identify the most eycient method to estimate root biomass for young and adult oil palm trees in situ. Three me-thods based on the sampling excavation volume were compared on the same sampled tree. Working time and manpower required for each operation were recorded. We compared two large excavation techniques based on the Voronoi tessellation procedure (full and half trench) with root auger coring method. Two industrial plantations of oil palm trees, of the same genetic material, aged 2- and 16-year old, were studied in Benin, West Africa. Oil palm root biomass was estimated t...
Ce rapport fait le bilan de l'exercice 2006 et fixe les principaux objectifs de 2007 du Progr... more Ce rapport fait le bilan de l'exercice 2006 et fixe les principaux objectifs de 2007 du Programme d'Interet Commun (PIC) signe en mai 2002 entre Le Cirad-Cultures Perennes et l'INRAB. Ce programme qui, a l'origine, ne concernait que l'amelioration et la diffusion du materiel vegetal du palmier a huile est, depuis janvier 2005, un PIC palmier a huile portant sur l'ensemble des disciplines de la filiere palmier a huile. La production et la diffusion de materiel ameliore constituent toujours un axe fort du PIC INRAB-Cirad. Les activites 2006 se sont inscrites dans la continuite des actions demarrees en 2002 visant a accroitre la qualite et la capacite de production, que ce soit directement a partir de la station de Pobe ou indirectement via des champs semenciers sous licence. A Pobe, les principaux investissements et recrutements realises rendent desormais possible une production de plus de 8 millions de semences, mais les objectifs sont maintenant d'ajuster...
Journal of Applied Biosciences, 2020
Objectif: La sécheresse observée en Afrique sub-saharienne est responsable de précipitations de p... more Objectif: La sécheresse observée en Afrique sub-saharienne est responsable de précipitations de plus en plus irrégulières d’une année à une autre qui rendent difficile la sélection et la recommandation des génotypes performants de palmier à huile. L’objectif de cette étude est d’évaluer et de classer des génotypes de palmier à huile selon leurs degrés de performance et de stabilité au fil des années. Méthodologie et résultats : Pour ce faire, des données de rendement ont été analysées chez neuf génotypes de palmier (L1 à L9) sur 18 campagnes de production (de 2000-2001 à 2018-2019) à l’aide de l’indice de supériorité génotypique (Pi) et de la régression linéaire simple. Les résultats obtenus ont montré que les génotypes L1, L2, L6 et L8 sont performants et stables et que le génotype L2 présente une adaptation spécifique aux années contraignantes. En revanche, les génotypes L3, L4, L5 et L9 sont considérés comme des génotypes peu performantes et instables. Le génotype L7 quant à lui,...
La prediction de la valeur genetique clonale est l'une des limites actuelles a l'ameliora... more La prediction de la valeur genetique clonale est l'une des limites actuelles a l'amelioration genetique du rendement chez palmier a huile. Elle se base uniquement sur la valeur propre des candidats tetes de clones, souvent peu precise compte tenu de la faible heritabilite de certaines composantes du rendement. La presente etude a evalue la possibilite de predire la valeur genetique des hybrides tetes de clones avec des donnees genomiques haute densite. Le genotypage par sequencage a revele 15055 marqueurs de type polymorphisme a un nucleotide (SNP). Les precisions de deux approches de selection genomique (SG) ont ete evaluees sur huit composantes du rendement. La population de calibration etait de 295 et 279 croisements DELI x LM pour les composantes de production et de qualite des regimes, respectivement, et la population de validation comportait 42 clones DELI x LM. L'effet de la densite de marquage et de la modelisation de l'origine parentale des alleles ont ete e...
Bulletin de la Société entomologique de France, 2017
A new design of interception trap has been developed to study the activity of two major oil palm ... more A new design of interception trap has been developed to study the activity of two major oil palm pollinator insects, the weevils Elaeidobius spp. and Grasidius hybridus, visiting inflorescences in anthesis. The trap has been studied for the two species Elaeis guineensis (West Africa, Southeast Asia and South America) and Elaeis oleifera and two interspecific hybrids (South America). The results allowed the identification of the period of insect activity during anthesis and the monitoring of the species and number of insects visiting both male and female inflorescences in anthesis. The trap design seems convenient for future population dynamics and dispersal studies in oil palm plantations. The results indicate that Elaeidobius spp. have diurnal flying activity whereas such activity occurs during dusk to nocturnal periods for G. hybridus. The weevils are highly host-specific, but variability is apparent for hybrids. Résumé.-Étude de l'activité des populations d'Elaeidobius spp. et Grasidius hybridus à l'aide d'une nouvelle méthode de piégeage pendant l'anthèse du Palmier à huile (Coleoptera, Curculionidae). Un nouveau modèle de piège à interception a été conçu pour étudier l'activité des principaux insectes pollinisateurs du palmier à huile, les charançons Elaeidobius spp. et Grasidius hybridus, au voisinage des inflorescences en anthèse. Le piège a été testé pour les deux espèces de palmier à huile, Elaeis guineensis en Afrique de l'Ouest, Asie du Sud-Est et Amérique du Sud, et Elaeis oleifera et deux hybrides interspécifiques en Amérique du Sud. Les résultats permettent d'identifier les périodes d'activité des insectes pendant l'anthèse et d'identifier les espèces et les effectifs des insectes visitant les inflorescences mâles et femelles en anthèse. Le modèle de piège apparaît performant pour les études de dynamique des populations et de dispersion dans les plantations de palmier à huile. Les résultats indiquent qu'Elaeidobius spp. a une activité de vol diurne alors que G. hybridus a une activité en début de nuit ou au cours de la nuit. Les charançons sont très spécifiques de leur plante-hôte mais il existe une variabilité au sein des hybrides.
Philosophical Transactions of the Royal Society of London. B, Biological Sciences, 1988
The various patterns of environmental sex determination in squamates, chelonians and crocodilians... more The various patterns of environmental sex determination in squamates, chelonians and crocodilians are described. High temperatures produce males in lizards and crocodiles but females in chelonians. Original experiments on the effects of incubation at 30 °C (100% females) or 33 °C (100% males) on development inAlligator mississippiensisare described. These include an investigation of the effect of exposing embryos briefly to a different incubation temperature on the sex ratio at hatching, and a study of the effects of 30 °C and 33 °C on growth and development of alligator embryos and gonads. A 7-day pulse of one temperature on the background of another was insufficient to alter the sex ratio dramatically. Incubation at 33 °C increased the rate of growth and development of alligator embryos. In particular, differentiation of the gonad at 33 °C was enhanced compared with 30 °C. A hypothesis is developed to explain the mechanism of temperature-dependent sex determination (TSD) in crocod...
Plant and Animal Genome XXIV Conference, Jan 10, 2016
Annals of Botany, Jun 28, 2011
† Background The African oil palm (Elaeis guineensis) is a monoecious species of the palm subfami... more † Background The African oil palm (Elaeis guineensis) is a monoecious species of the palm subfamily Arecoideae. It may be qualified as 'temporally dioecious' in that it produces functionally unisexual male and female inflorescences in an alternating cycle on the same plant, resulting in an allogamous mode of reproduction. The 'sex ratio' of an oil palm stand is influenced by both genetic and environmental factors. In particular, the enhancement of male inflorescence production in response to water stress has been well documented. † Scope This paper presents a review of our current understanding of the sex determination process in oil palm and discusses possible insights that can be gained from other species. Although some informative phenological studies have been carried out, nothing is as yet known about the genetic basis of sex determination in oil palm, nor the mechanisms by which this process is regulated. Nevertheless new genomics-based techniques, when combined with field studies and biochemical and molecular cytological-based approaches, should provide a new understanding of the complex processes governing oil palm sex determination in the foreseeable future. Current hypotheses and strategies for future research are discussed.
Cereal Research Communications, Dec 1, 2010
Literature confirms that using polyethylene glycol (PEG) as an osmotic agent to imitate water sho... more Literature confirms that using polyethylene glycol (PEG) as an osmotic agent to imitate water shortage was not so easy in practice, due to PEG toxicity effects and frequent contaminations. Two new approaches were developed to alleviate those problems, one using a raft covered with a membrane to prevent PEG entry in roots, and one using solidified PEG media. The raft trials were done on corn, hexaploid and tetraploid wheat, rye, triticale, oats, barley, Agrotricum; those in solid media, with corn, hexaploid and tetraploid wheat, barley, sorghum and pearl millet. Different species respond differently to PEG-induced osmotic stress. In our trials, the most sensitive cereal was corn, and this finding correlates with the lower osmotic pressure of the sap (a constitutive trait in corn seedlings). Corn responded to osmotic stress by a very poor rate of elongation of the coleoptile, especially when the highest stress (32% PEG) was used. This behavior was also observed in the field in dry years, for example in the Sahel area. Compared to this sensitive cereal species, all other cereals tested were more resistant. Hexaploid and tetraploid wheat, triticale, and Agrotricum kept capacity to elongate roots when submitted to a high osmotic stress, but the higher stress reduced root length considerably. Barley kept rooting ability like other cereals, but was able to develop more aerial biomass, seminal roots, and ramifications. Barley root hair was also longer and covered a higher proportion of the root. Those adaptive features likely explain part of the good adaptation of barley to dry Mediterranean areas. Preliminary results on solid media also showed relationships between drought resistance and the osmoresistance response, at least when comparing species. Roots of species adapted to hot climate, like pearl millet and sorghum, had few seminal roots but displayed a strong gravitropism under osmotic stress. The ease of use of solidified PEG media shows promise for future larger scale trials. Applications of solidified PEG media for research beyond cereal crops is envisioned.
Journal of insect science, 2015
The edibility of different Elaeis sp. breeding populations present in Benin was tested for the le... more The edibility of different Elaeis sp. breeding populations present in Benin was tested for the leaf miner Coelaenomenodera lameensis Berti (Coleoptera: Chrysomelidae), a major oil palm pest in Africa. Experiments carried out in sleeves revealed the oviposition capacities of females and the mortality rates for the different developmental stages by comparing the populations found on two breeding populations of Elaeis oleifera (HBK) Cortes, four of Elaeis guineensis Jacquin and four (E. guineensis  E. oleifera)  E. guineensis backcrosses. Females laid their eggs similarly on all breeding populations, with a preference for the E. guineensis La Mé origin. The average hatching rate reached 80% for the La Mé origin as opposed to 28% for the Deli origin. The mortality rates for the larval instars were greater on E. oleifera, on certain backcrosses and on the Deli origin of E. guineensis. Development at the second-and third-larval instars was the most affected, with a mortality rate of three to five times greater than that seen on La Mé. Epidermis and cuticle measurements indicated which breeding populations were suitable or unsuitable for the development of C. lameensis. E. guineensis, with its thin epidermis (12 mm) and cuticle (2 mm), proved to be highly susceptible to C. lameensis attacks. On the other hand, E. oleifera, which is very resistant, exhibited a thicker epidermis (17 mm) and cuticle (4 mm). The breeding populations were thus classified according to the positive or negative influence they exerted on the insect's egg laying and feeding. RÉSUMÉ. La comestibilité de différents matériels végétaux d'Elaeis sp. présents au Bénin est testée pour Coelaenomenodera lameensis Berti (Coleoptera: Chrysomelidae), important ravageur du palmier à huile en Afrique. Des expérimentations en manchons ont permis de déterminer les capacités d'oviposition des femelles et les taux de mortalité des différents stades de développement (oeufs, larves, nymphes et adultes) en comparant les populations observées sur deux origines d'Elaeis oleifera (HBK) Cortes, quatre origines d'Elaeis guineensis Jacquin et quatre Backcross (E. guineensis  E. oleifera)  E. guineensis. Les femelles pondent indifféremment sur tous les types de matériel végétal avec une préférence pour l'origine La Mé d'E. guineensis. Le taux moyen d'éclosion atteint 80% pour l'origine La Mé contre 28% pour l'origine Deli. Le taux de mortalité des stades larvaires est plus important sur E. oleifera, sur certains Backcross et sur l'origine Deli d'E. guineensis. Le développement des deuxiè me et troisiè me stades larvaires sont les plus affectés avec un taux de mortalité 3 à 5 fois supérieur à celui observé sur La Mé. Des mesures d'épiderme et de cuticule mettent en évidence l'existence de matériel végétal favorable ou défavorable au développement de C. lameensis. E. guineensis dont l'épiderme (12 mm) et la cuticule (2 mm) sont peu épais se révèle être trè s sensible aux attaques de C. lameensis. Au contraire, E. oleifera présente un épiderme (17 mm) et une cuticule (4 mm) plus épais et est très résistants. Le matériel végétal est ainsi classé suivant l'influence positive ou négative qu'ils exercent sur la ponte et l'alimentation des insectes.
Journal of Applied Biosciences, May 13, 2019
Objectives: Fusarium wilt is the first oil palm pathology, who devastates the plantations in Afri... more Objectives: Fusarium wilt is the first oil palm pathology, who devastates the plantations in Africa. The currents study aims to diagnose the spatial distribution of this pathology and the incidence of the disease caused by Fusarium oxysporum elaeidis (Foe) in the palm oil growing zone of Benin. Methodology and Results: Thus, a survey was carried out in May 2018 covering 16 plantations distributed in four agroecological zones of production of palm oil in Benin. In each plantation, 15 plants were randomly inspected to evaluate the incidence, the severity, and the distribution of the disease. Root and soil samples were collected at the foot of each evaluated tree, at a depth of 20 cm using an auger. Samples were stored in polyetilene bags, for the detection and isolation of the pathogenic agent. The results showed that incidence is significantly different depending on the agroecological zones prospected (p=0.000). Central Cotton Zone (Kétou) and the Fisheries Zone (Adjohoun) recorded an incidence of vascular wilt of 0%, whereas on the sites surveyed in the Depression Zone (Pobè, Adja-Ouèrè) and the Bar Land Zone (Ifangni, Missérété, Sakété, Adjarra) the recorded disease incidences were 30.0% and 12.5%, respectively. This study also revealed an uneven distribution of the pathogen on the sites surveyed. Indeed, the study of the soil samples taken at the foot of the plants revealed that the presence of Foe does not systematically induce the disease, or induces it to varying levels, although the isolate is pathogenic and the material planted on each site is identical. Conclusions and application of results: These results demonstrate a polymorphism of oil palm susceptibility to Fusarium wilt and underline the need to define a new screening approach based on the susceptibility factors of oil palm and which minimizes the intra-crossing variations observed.
Journal of Applied Biosciences, 2019
Importance des manifestations des symptômes de déficience minérale du palmier à huile (Elaeis gui... more Importance des manifestations des symptômes de déficience minérale du palmier à huile (Elaeis guineensis Jacq.) dans les plantations paysannes au Sud-Bénin en Afrique de l'Ouest
European Network of Palm Scientists, 2018
BASE, 2017
Introduction. L’acidification de l’huile de palme détermine la qualité et la stabilité de cette i... more Introduction. L’acidification de l’huile de palme détermine la qualité et la stabilité de cette importante denrée alimentaire. Cette synthèse analyse les causes de l’acidification de l’huile et son impact sur la qualité et la stabilité de l’huile. Les enjeux liés à la réduction de l'acidification de l'huile et les approches utilisées sont aussi analysés, en particulier la réduction par l’amélioration génétique. Littérature. L'acidification est principalement due à l’action de la lipase endogène du mésocarpe, mais peut aussi être causée par des lipases microbiennes ou une hydrolyse autocatalytique. Plusieurs facteurs, notamment le matériel végétal, les conditions de récolte et de traitement post-récolte des régimes, d’extraction et de conservation de l’huile impactent de manière significative l’acidification de l'huile. L’acidification réduit la qualité et la valeur marchande de l’huile et engendre une baisse de productivité. Des fonds génétiques à faible acidité ont ...
Plants, 2022
Sexual differentiation of inflorescences and flowers is important for reproduction and affects cr... more Sexual differentiation of inflorescences and flowers is important for reproduction and affects crop plant productivity. We report here on a molecular study of the process of sexual differentiation in the immature inflorescence of oil palm (Elaeis guineensis). This species is monoecious and exhibits gender diphasy, producing male and female inflorescences separately on the same plant in alternation. Three main approaches were used: small RNA-seq to characterise and study the expression of miRNA genes; RNA-seq to monitor mRNA accumulation patterns; hormone quantification to assess the role of cytokinins and auxins in inflorescence differentiation. Our study allowed the characterisation of 30 previously unreported palm MIRNA genes. In differential gene and miRNA expression studies, we identified a number of key developmental genes and miRNA-mRNA target modules previously described in relation to their developmental regulatory role in the cereal panicle, notably the miR156/529/535-SQUAM...
Plant and Soil, 2021
Background and aims Root biomass is one of the most widely used parameters to characterise root g... more Background and aims Root biomass is one of the most widely used parameters to characterise root growth and belowground carbon stock. Our aim was to define a standard method to estimate the root biomass of young and adult oil palm trees in commercial plantations. Methods Three methods based on the sampling excavation volume were compared using the same sampled tree. Work time and the number of workers required for each operation were recorded. We compared two large excavation volumes based on Voronoi tessellation and the standard root auger coring method in one 2year-old and one 16-year-old commercial oil-palm plantation in Benin, West Africa. Results Oil palm total root biomass was estimated at 0.84 and 22.23 Mg ha −1 in the 2-year-old and 16-yearold plantation, respectively. Compared to the reference method, the simplified Voronoi trench method estimated slightly higher (+5%) and lower (−17%) total root biomass with no significant differences but required 2 and 3 times more labour time, respectively, while the auger method estimated significantly lower (−23% and − 53%) total root biomass in the 2-year-old and 16-yearold plantation, respectively. Coarse and fine root biomass were significantly higher under the windrow than under the footpath zones. Conclusion The simplified Voronoi trench method required twice as much labour time as the auger method but was most efficient way to estimate oil palm total root biomass, irrespective of the age of the plantation.
Good management practice in oil palm rely on accurate predictions of fertiliser require-ments tha... more Good management practice in oil palm rely on accurate predictions of fertiliser require-ments that respect the environment and are economically optimal. A study performed in Indonesia pointed out that K and Mg leaf contents greatly vary from one oil palm progeny to another for the same production level. Such differences in nutrient contents may lead to an incorrect assessment of the nutrient requirements, questioning the validity of leaf analysis as a diagnostic tool and raise several research questions: Do oil palm progenies with different leaf nutrient contents need to be fertilised with specifics fertilisation tables? Does the difference in leaf nutrient contents between progenies reflect different patterns for nutrient allocation within plant tissues? Do mineral absorption and fertiliser recovery eyciency differ according to oil palm progenies? and to what extend so far? Is there any progeny which can adapt itself to agronomic practices requiring less fertiliser for highest prod...
There is still a large potential for the genetic improvement of yield in oil palm, as it has only... more There is still a large potential for the genetic improvement of yield in oil palm, as it has only been submitted to a few generations of modern breeding. Selection candidates are traditionally evaluated in progeny tests, as some yield components have a low heritability. The progeny-tests allow selecting with a high accuracy, but constrain the rate of genetic gain as they increase the generation interval and limit the number of evaluated individuals. Genomic selection (GS) is an appealing alternative to the current phenotypic selection, as it could allow selecting without progeny tests. Here, we studied the prediction accuracy of GS in the two heterotic groups used to produce oil palm commercial hybrids, ie the correlation between the genomic estimated breeding values and the breeding values obtained from the conventional method of phenotypic selection. We used two independent experimental designs located in Sumatra (Indonesia), comprising over 700 hybrid crosses. The GS model was ca...
Root biomass is one of the most used parameter to characterise root development and distribution ... more Root biomass is one of the most used parameter to characterise root development and distribution within soil. However, different methods exist with regards to plant root system architecture, soil sampling volume and planting design but no standard protocol were set up for Monocotyledonous trees in an equilateral triangle planting design and comparing different ages of plantation. The purpose of this work was to identify the most eycient method to estimate root biomass for young and adult oil palm trees in situ. Three me-thods based on the sampling excavation volume were compared on the same sampled tree. Working time and manpower required for each operation were recorded. We compared two large excavation techniques based on the Voronoi tessellation procedure (full and half trench) with root auger coring method. Two industrial plantations of oil palm trees, of the same genetic material, aged 2- and 16-year old, were studied in Benin, West Africa. Oil palm root biomass was estimated t...
Ce rapport fait le bilan de l'exercice 2006 et fixe les principaux objectifs de 2007 du Progr... more Ce rapport fait le bilan de l'exercice 2006 et fixe les principaux objectifs de 2007 du Programme d'Interet Commun (PIC) signe en mai 2002 entre Le Cirad-Cultures Perennes et l'INRAB. Ce programme qui, a l'origine, ne concernait que l'amelioration et la diffusion du materiel vegetal du palmier a huile est, depuis janvier 2005, un PIC palmier a huile portant sur l'ensemble des disciplines de la filiere palmier a huile. La production et la diffusion de materiel ameliore constituent toujours un axe fort du PIC INRAB-Cirad. Les activites 2006 se sont inscrites dans la continuite des actions demarrees en 2002 visant a accroitre la qualite et la capacite de production, que ce soit directement a partir de la station de Pobe ou indirectement via des champs semenciers sous licence. A Pobe, les principaux investissements et recrutements realises rendent desormais possible une production de plus de 8 millions de semences, mais les objectifs sont maintenant d'ajuster...
Journal of Applied Biosciences, 2020
Objectif: La sécheresse observée en Afrique sub-saharienne est responsable de précipitations de p... more Objectif: La sécheresse observée en Afrique sub-saharienne est responsable de précipitations de plus en plus irrégulières d’une année à une autre qui rendent difficile la sélection et la recommandation des génotypes performants de palmier à huile. L’objectif de cette étude est d’évaluer et de classer des génotypes de palmier à huile selon leurs degrés de performance et de stabilité au fil des années. Méthodologie et résultats : Pour ce faire, des données de rendement ont été analysées chez neuf génotypes de palmier (L1 à L9) sur 18 campagnes de production (de 2000-2001 à 2018-2019) à l’aide de l’indice de supériorité génotypique (Pi) et de la régression linéaire simple. Les résultats obtenus ont montré que les génotypes L1, L2, L6 et L8 sont performants et stables et que le génotype L2 présente une adaptation spécifique aux années contraignantes. En revanche, les génotypes L3, L4, L5 et L9 sont considérés comme des génotypes peu performantes et instables. Le génotype L7 quant à lui,...
La prediction de la valeur genetique clonale est l'une des limites actuelles a l'ameliora... more La prediction de la valeur genetique clonale est l'une des limites actuelles a l'amelioration genetique du rendement chez palmier a huile. Elle se base uniquement sur la valeur propre des candidats tetes de clones, souvent peu precise compte tenu de la faible heritabilite de certaines composantes du rendement. La presente etude a evalue la possibilite de predire la valeur genetique des hybrides tetes de clones avec des donnees genomiques haute densite. Le genotypage par sequencage a revele 15055 marqueurs de type polymorphisme a un nucleotide (SNP). Les precisions de deux approches de selection genomique (SG) ont ete evaluees sur huit composantes du rendement. La population de calibration etait de 295 et 279 croisements DELI x LM pour les composantes de production et de qualite des regimes, respectivement, et la population de validation comportait 42 clones DELI x LM. L'effet de la densite de marquage et de la modelisation de l'origine parentale des alleles ont ete e...
Bulletin de la Société entomologique de France, 2017
A new design of interception trap has been developed to study the activity of two major oil palm ... more A new design of interception trap has been developed to study the activity of two major oil palm pollinator insects, the weevils Elaeidobius spp. and Grasidius hybridus, visiting inflorescences in anthesis. The trap has been studied for the two species Elaeis guineensis (West Africa, Southeast Asia and South America) and Elaeis oleifera and two interspecific hybrids (South America). The results allowed the identification of the period of insect activity during anthesis and the monitoring of the species and number of insects visiting both male and female inflorescences in anthesis. The trap design seems convenient for future population dynamics and dispersal studies in oil palm plantations. The results indicate that Elaeidobius spp. have diurnal flying activity whereas such activity occurs during dusk to nocturnal periods for G. hybridus. The weevils are highly host-specific, but variability is apparent for hybrids. Résumé.-Étude de l'activité des populations d'Elaeidobius spp. et Grasidius hybridus à l'aide d'une nouvelle méthode de piégeage pendant l'anthèse du Palmier à huile (Coleoptera, Curculionidae). Un nouveau modèle de piège à interception a été conçu pour étudier l'activité des principaux insectes pollinisateurs du palmier à huile, les charançons Elaeidobius spp. et Grasidius hybridus, au voisinage des inflorescences en anthèse. Le piège a été testé pour les deux espèces de palmier à huile, Elaeis guineensis en Afrique de l'Ouest, Asie du Sud-Est et Amérique du Sud, et Elaeis oleifera et deux hybrides interspécifiques en Amérique du Sud. Les résultats permettent d'identifier les périodes d'activité des insectes pendant l'anthèse et d'identifier les espèces et les effectifs des insectes visitant les inflorescences mâles et femelles en anthèse. Le modèle de piège apparaît performant pour les études de dynamique des populations et de dispersion dans les plantations de palmier à huile. Les résultats indiquent qu'Elaeidobius spp. a une activité de vol diurne alors que G. hybridus a une activité en début de nuit ou au cours de la nuit. Les charançons sont très spécifiques de leur plante-hôte mais il existe une variabilité au sein des hybrides.