100 research outputs found
Etude de la sensibilitĂ© des clones dâHevea brasiliensis (Muell. Arg.) Ă lâencoche sĂšche
Chez Hevea brasiliensis, la production de latex est affectĂ©e par lâencoche sĂšche qui se manifeste par lâarrĂȘt de lâĂ©coulement de latex aprĂšs la saignĂ©e. La sensibilitĂ© clonale Ă cette maladie est mal connue. La prĂ©sente Ă©tude a pour objectif dâĂ©tablir une classification des clones les plus plantĂ©s en CĂŽte dâIvoire selon leur sensibilitĂ© Ă lâencoche sĂšche, dans des conditions dâexploitation utilisant divers niveaux de stimulations Ă lâEthrel. La mĂ©thode utilisĂ©e est lâanalyse de variances des longueurs dâencoche malade collectĂ©es pendant cinq ans. Les rĂ©sultats ont montrĂ© que les clones dâhĂ©vĂ©a nâont pas la mĂȘme sensibilitĂ© Ă lâencoche sĂšche. Les clones IRCA41, PB 217, AF 261 et RRIM 712 sont peu sensibles ; IRCA 130, AVROS 2037, IRCA 209 et GT 1 sont moyennement sensibles ; RRIC 100, IRCA 230, et PB 254, sont sensibles ; et PB 260 et PB 235 sont trĂšs sensibles. La sensibilitĂ© clonale Ă lâencoche sĂšche suit un gradient identique Ă celui de lâactivitĂ© mĂ©tabolique des clones. Elle est corrĂ©lĂ©e positivement Ă la frĂ©quence de stimulation de lâarbre Ă lâEthrel. Les clones peu sensibles supportent mieux la stimulation Ă lâEthrel Ă lâopposĂ© des clones trĂšs sensibles. Dans une parcelle monoclonale, certains arbres seraient prĂ©disposĂ©s Ă exprimer, prĂ©cocement, lâencoche sĂšche.In rubber tree, Hevea brasiliensis, latex production is affected by tapping panel dryness that appears by stopping the latex out-flow after bled. The clonal sensitivity to this disease is not well known. The objective of the present study is to establish a classification of the more planted clones in CĂŽte dâIvoire according to tapping panel dryness sensitivity, in operating conditions using various Ethrel stimulations levels. The method used is the analysis of variances of the panel sick lengths collected during five years. The results showed that rubber tree Hevea brasiliensis clones have not the same sensitivity to tapping panel dryness. The IRCA41, PB 217, AF 261 and RRIM 712 clones are little sensitive; IRCA 130, AVROS 2037, IRCA 209 and GT 1, are fairly sensitive ; RRIC 100, IRCA 230, and PB 254, are sensitive ; and PB 260 and PB 235, are very sensitive. The clonal sensitivity to tapping panel dryness follows a gradient identical to those of the clonesâ metabolic activity. Itâs positively correlated to the Ethrel stimulation frequency. Little sensitive clones support the Ethrel stimulation better than very sensitive clones. In a monoclonal plot, some trees would be predisposed to express tapping panel dryness precociously.Mots clĂ©s/Keywords : Hevea brasiliensis, encoche sĂšche, sensibilitĂ©, CĂŽte dâIvoir
Effet dâune souche non pathogĂšne de Fusarium oxysporum sur lâexpression de la fusariose chez le palmier Ă huile (Elaeis guineensis Jacq.)
Cette Ă©tude avait pour objectif dâĂ©valuer la rĂ©action vis-Ă -vis de la fusariose de plantules de palmier Ă huile prĂ©munies auparavant dâune souche non pathogĂšne de Fusarium oxysporum. LâĂ©valuation a portĂ© sur des plantules issues dâun croisement tolĂ©rant et dâun croisement non tolĂ©rant Ă la fusariose. Les rĂ©sultats ont montrĂ©, quâaprĂšs quatre mois dâinoculation de lâagent pathogĂšne, 0% et 2,5% de plants malades ont Ă©tĂ© observĂ©s respectivement chez les plantules issues du croisement tolĂ©rant et du croisement non tolĂ©rant Ă la fusariose. Par contre, lorsque les plantules nâont pas Ă©tĂ© prĂ©-inoculĂ©es avant avec la souche non pathogĂšne de Fusarium oxysporum, le pourcentage cumulĂ© de fusariose, aprĂšs quatre mois dâincubation de lâagent pathogĂšne, a variĂ© entre 7,5% et 12,5% pour le croisement tolĂ©rant et de 14,5% Ă 47,5% pour le croisement non tolĂ©rant Ă la fusariose. Il ressort donc de lâĂ©tude que lâinoculation, Ă un croisement sensible dâune souche non agressive de Fusarium oxysporum pouvait lui confĂ©rer le pouvoir fongitoxique et amĂ©liorer la fongitoxicitĂ© chez un croisement tolĂ©rant.Mots clĂ©s : Induction, fongitoxicitĂ©, agent non agressif, prĂ©munition
Evaluation de lâintrogression du caractĂšre croissance lente de quelques gĂ©niteurs Akpadanou (origine BĂ©nin) chez quelques gĂ©niteurs amĂ©liorĂ©s de palmier Ă huile (E. guineensis Jacq.) de lâorigine La MĂ© (CĂŽte dâIvoire)
La vitesse de croissance en hauteur de 294 arbres appartenant Ă 11 descendances de palmier Ă huile a étĂ© Ă©valuĂ©e selon la mĂ©thode dĂ©crite par Jacquemard (1980). Ces descendances ont Ă©tĂ© obtenues Ă partir de plusieurs croisements de type (AKN3 x La MĂ©) x La MĂ© et (AKN3 x La MĂ©) x (La MĂ© x La MĂ©) qui visaient Ă Â introduire le caractĂšre croissance lente de lâorigine Akpadanou (Benin) chez des gĂ©niteurs amĂ©liorĂ©s de lâorigine La MĂ©, CĂŽte dâIvoire. Les descendances ont Ă©tĂ© comparĂ©es Ă un tĂ©moin vulgarisĂ© de type DA10D x LM2T. Les rĂ©sultats ont montrĂ© que lâensemble des descendances testĂ©es ont une vitesse de croissance en hauteur moyenne infĂ©rieure au tĂ©moin. En effet, les valeurs obtenues ont variĂ© de 19,86 Ă 35,89 cm/an au sein de ces descendances testĂ©es, contre 45,25 cm/an pour le tĂ©moin de lâessai. Une rĂ©duction de plus de 20% de la vitesse de croissance en hauteur a donc Ă©tĂ© observĂ©e au niveau de ces descendances. Ces rĂ©sultats laissent entrevoir la perspective de sĂ©lection, Ă terme, de matĂ©riel vĂ©gĂ©tal Ă croissance en hauteur fortement rĂ©duite et possĂ©dant un bon niveau de production de rĂ©gimes et dâhuile de palme.Mots clĂ©s : SĂ©lection, palmier amĂ©liorĂ©, croissance en hauteur rĂ©duite
Performance de deux techniques dâextraction des phĂ©nols racinaires pour lâĂ©valuation du marquage de la tolĂ©rance Ă la fusariose des clones de palmier a huile (Elaeis guineensis jacq.)
Les premiĂšres Ă©tudes sur les mĂ©canismes de dĂ©fense du palmier Ă huile ont mis en Ă©vidence le rĂŽle des composĂ©s phĂ©noliques dans la tolĂ©rance Ă la fusariose des clones et croisements Ă partir des racines inoculĂ©es par lâagent pathogĂšne. Notre travail a consistĂ© dâune part Ă amĂ©liorer les premiĂšres techniques dâextraction en remplaçant lâEthanol par un mĂ©lange Ethanol-eau et dâautre part Ă amĂ©liorer les techniques de microanalyses des marqueurs de tolĂ©rance Ă la fusariose. Les rĂ©sultats ont montrĂ© que les modifications apportĂ©es ont permis dâaccĂ©der Ă une quantitĂ© plus importante de phĂ©nols que la mĂ©thode classique. En outre, les analyses des phĂ©nols totaux et la fongitoxicitĂ© ont permis de discriminer les clones tolĂ©rants des clones sensibles. Ces nouvelles mĂ©thodes nous ont permisdâĂ©valuer plus rapidement la tolĂ©rance Ă la fusariose des clones aprĂšs inoculation de lâagent pathogĂšne.The early studies on the defence mechanisms of the oil palm tree put in evidence the role of phenolic compounds in the tolerance of wilt disease of the clones and crossings from the roots inoculated by the pathogenic agent. Our work consists on one hand in improving the first techniques of extraction by replacing the Ethanol by a mixing Ethanol-water and on the other hand by improving the techniques of microanalyses of the tolerance markers to wilt disease. The results showed that these modifications permitted to reach a quantity more important of phenol than the classic method. Besides, the analyses of the total phenol and the fongitoxicity permitted to discriminate the tolerant clones from the sensitive clones. These new methods allow us to evaluate faster the tolerance to wilt disease of the clones after inoculation of the pathogenic agentMots clĂ©s : Palmier Ă huile â Fusarium â PhĂ©nols â Clones â extraction
Evaluation du pouvoir disjonctif des variables catĂ©gorielles impliquĂ©es dans la sĂ©lection du palmier Ă huile (Elaeis guineensis jacq.) en CĂŽte dâIvoire
En amĂ©lioration gĂ©nĂ©tique du palmier Ă huile (Elaeis guineensis Jacq.), les variables catĂ©gorielles constituent une part majoritaire de lâinformation utilisĂ©e pour diffĂ©rencier, les populations de gĂ©niteurs issus du programme de sĂ©lection rĂ©currente rĂ©ciproque (SRR). Le pouvoir disjonctif de ces variables a Ă©tĂ© testĂ© sur 134 gĂ©niteurs sĂ©lectionnĂ©s issus des populations du premier, deuxiĂšme et troisiĂšme cycle de SRR. Les variables catĂ©gorielles utilisĂ©es pour diffĂ©rencier ces populations sont celles qui ont permis dâavoir des informations sur les origines gĂ©ographiques et les gĂ©nĂ©alogies parentales des gĂ©niteurs. Lâanalyse factorielle de lâensemble de ces variables catĂ©gorielles, a permis de dĂ©terminer le pouvoir disjonctif de chacun des deux principaux critĂšres de divergences des populations de gĂ©niteurs sĂ©lectionnes. Le critĂšre "origine gĂ©ographique" a reprĂ©sentĂ© 14 % dâexpression de disjonction totale des populations de gĂ©niteurs sĂ©lectionnĂ©s. Le critĂšre "gĂ©nĂ©alogie parentale" a reprĂ©sentĂ© 70 % dâexpression de disjonction totale des populations de gĂ©niteurs sĂ©lectionnĂ©s. Lâutilisation de ces deux critĂšres de diffĂ©renciation des populations de gĂ©niteurs sĂ©lectionnĂ©es peut constituer une bonne alternative Ă lâutilisation des donnĂ©es molĂ©culaires dans les Ă©tudes de la diversitĂ© des populations de palmier Ă huile en sĂ©lection.Mots-clĂ©s : Palmier Ă huile, sĂ©lection, variable catĂ©gorielle, disjonction de populatio
Essai de lutte contre oryctes monoceros olivier (coleoptera : dynastidae) par lâutilisation de lâacide 4-mĂ©thyloctanoĂŻque en cĂŽte -dâivoire
(Arecaceae), en CĂŽte dâIvoire. Pour lutter contre ce ravageur, lâacide 4-methyloctanoĂŻque a Ă©tĂ© initiĂ©. Au cours de ces travaux, 3 types de diffuseurs (Da, Db, Dc) contenant les diffĂ©rentes doses ont Ă©tĂ© expĂ©rimentĂ©s. LâĂ©tude a Ă©tĂ© menĂ©e sur 9 mois repartie sur 4 phases dont 1 mois sans diffuseurs, 4 mois avec diffuseurs, 2 mois retrait desdiffuseurs et 2 mois post diffuseurs. Les visites des cocotiers ont Ă©tĂ© effectuĂ©es 3 fois par semaine avec extraction des insectes des galeries en notant les caractĂ©ristiques climatiques et le sexe des insectes. Les diffuseurs ont Ă©tĂ© pesĂ©s au dĂ©but et chaque mois pendant la phase avec diffuseurs. On note que les trois types de diffuseurs ont la mĂȘme efficacitĂ© contre les attaques de O. monoceros mais le diffuseur Dc, caractĂ©risĂ© par la dose faible, est Ă©conomiquement plus avantageux et pourrait ĂȘtre vulgarisĂ© auprĂšs des paysans, pour la protection de leurs plantations.Mots clĂ©s : Cocos nucifera, Oryctes monoceros, Diffuseurs, Acide 4-mĂ©thyloctanoĂŻqueOryctes monoceros Olivier is one of the most dangerous pests of young coconuts Cocos nucifera Linne (Arecaceae) in CĂŽte-dâIvoire. In order to reduce their populations, 4-methyloctanoĂŻc acid was initiated. In this work, 3 different types of diffusers (Da, Db, Dc) was tested. The study over nine months covered four phases with one month (without diffusers), four month (with diffusers), two month (diffuser withdrawal) and two month (post diffuser). Coconuts were visited 3 twice in a week by collecting insects of galleries and wrote down climatic characteristics, sex of insects. Diffusers were weighted at the beginning and every month during phase with diffusers. We notice that three types of diffusers have the same effectiveness against O. monoceros attacks, diffuser Dc, characterized by a low concentration, is economically more reasonable and could be recommended to the farmer for the protection of their plantations
Assessment of the Efficiency of Insecticide Paint and Impregnated Nets on Tsetse Populations: Preliminary Study in Forest Relics of Abidjan, CĂŽte dâIvoire
Glossina palpalis palpalis is the main vector of human and animal trypanosomiasis in CĂŽte dâIvoire. This species, being the only tsetse species in the city of Abidjan, is hosted by the National park of Banco located in the middle of Abidjan, the zoological park and in a relic forest within the University of Nangui-Abrogoua, both in Abidjan. A programme for the elimination of these suburban tsetse populations has been initiated, in the context of which various tsetse control tools have been evaluated. In the zoological park, insecticidal paint (InesflyÂź) was applied around the animal cages, and then supplemented with insecticide-impregnated netting around the larger animal cages. Tsetse population densities were monitored with Vavoua-style traps both inside the zoological park and in the site of University Nangui Abrogoua used as control site. Tsetse densities in the traps fell by over 90% following application of the insecticidal paint, and declined to zero after adding the insecticide impregnated nets in both study sites. The study confirms the close contact between tsetse populations from the zoological park and the University Nangui Abrogoua area, and shows that the sequential use of insecticide paint and impregnated nets can be effective for tsetse control
Facteurs affectant la reprise au sevrage des vitroplants enracinés de palmier à huile (Elaeis guineensis Jacq.) régénérés par embryogÚnese somatique
LâĂ©levage des vitroplants de palmier Ă huile (Elaeis guineensis Jacq.) pour les amener au stade de plants plantables comprend une phase prĂ©liminaire dĂ©licate. Il sâagit du sevrage, qui a pour but de les acclimateraux conditions naturelles. Cette Ă©tape nâexcĂšde pas trois Ă quatre semaines. MalgrĂ© la mise au point de nouvelles conditions de sevrage plus adaptĂ©es, lâon enregistre des pertes rĂ©siduelles augmentant ainsi le coĂ»t de production de vitroplants. Pour y remĂ©dier, les facteurs qui influencent une bonne reprise en acclimatation ont Ă©tĂ© recherchĂ©s Ă partir de 70 000 plants sortis des tubes dâenracinement. A la fin de 3 semaines de sevrage, les plants vivants ont Ă©tĂ© comptĂ©s, puis les pourcentages de reprise pour chacune des 81 combinaisons constituĂ©es de plants ont Ă©tĂ© calculĂ©s. Le pourcentage moyen global de reprise a Ă©tĂ© dâenviron 90 % pour lâensemble des combinaisons. NĂ©anmoins, les rĂ©sultats sur plusieurs sorties ont mis en Ă©vidence une influence significative de la qualitĂ©Â morphologique des plants enracinĂ©s. La reprise dĂ©pend fortement du dĂ©veloppement foliaire, notamment la taille des plants racinĂ©s. La bonne qualitĂ© des racines produites in vitro concourt aussi au succĂšs de la reprise en lâacclimatation, mais ce facteur nâest pas dĂ©terminant. Le nombre de racines est sans effet notable, mais interagit avec les deux autres variables. Les plantules ayant enregistrĂ© un bon dĂ©veloppement foliaire et racinaire (Groupe A), celles moyennement bien dĂ©veloppĂ©es (Groupe B) ainsi que celles faiblement dĂ©veloppĂ©es ont exprimĂ© respectivement 97 %,91 % et 77 % de taux de reprise. Le taux de reprise global des plants transfĂ©rĂ©s en sol Ă©tait de 92 %, grĂące Ă une mĂ©thode de sevrage simple qui assure, pendant 3 Ă 4 semaines, une adaptation progressive desplants aux conditions naturelles et qui regroupe les plants en classes de racines.Mots clĂ©s : Culture in vitro, palmier Ă huile, enracinement, sevrage, taux de reprise. FACTORS INFLUENCING THE RECOVERY DURING THE WEANING STAGE OF THE OIL PALM RAMETS REGENERATED VIA SOMATIC EMBRYOGENESISRaising in vitro plantlets of the oil palm (Elaeis guineensis Jacq.) regenerated via somatic embryogenesis to the stage where they are ready to be planted includes preliminary delicate phase - weaning - which is intended acclimatize them to natural conditions. This stage doesnât exceed 3 to 4 weeks. In spite of the development of new conditions of weaning more adapted, we note residual losses increasing the production costs of to ramets. To remedy there, the factors influencing a good recovery in acclimatization of oil palm vitroplants regenerated by somatic embryogenesis were investigated using 70,000 plantlets taken out fromrooting tubes. Three weeks after the weaning, the alive plantlets were scored, and then the percentages of recovery for each of the 81 plants combinations were calculated. The total average percentage of recovery was approximately 90 %. Nonetheless, the results observed on several outlets showed a significant influence of the morphological quality of rooted plantlets. The recovery strongly depends on the leaf growth, in particular the height of rooted plantlets. The good quality of roots produced with in vitro culture alsocontributes to the success of acclimatization, but this factor is not determining. In contrast, the roots number does not influence acclimatization, but is correlated with two other variables. Plantlets with good leaf and root growth (Group A), those fairly grown (Group B), as well as those weakly grown (Group C) expressed a success rate of 97 %, 91 % and 77 %, respectively. The overall rate of recovery of plantlets transferred in ground was 92 %, thanks to a simple method of weaning which provides for 3 to 4 weeks, a gradual adaptation of plantlets to natural conditions and which clusters the plantlets in root clusters.Keywords : In vitro culture, recovery rate, somatic embryo-derived plantlets, rooting, recovery percentage, weaning
Phenetic and genetic structure of tsetse fly populations (Glossina palpalis palpalis) in southern Ivory Coast
Background: Sleeping sickness, transmitted by G. p. palpalis, is known to be present in the Ivory Coast. G. p. palpalis has recently been reported to occur in several places within the town of Abidjan, including: (i) the Banco forest, (ii) the Abobo Adjame University campus and (iii) the zoological park. Could these three places be treated sequentially, as separate tsetse populations, or should they be taken as one area comprising a single, panmictic population? Methods: The amount of gene flow between these places provides strategic information for vector control. It was estimated by the use of both microsatellite DNA and morphometric markers. The idea was to assess the interest of the faster and much less expensive morphometric approach in providing relevant information about population structure. Thus, to detect possible lack of insect exchange between these neighbouring areas of Abidjan, we used both genetic (microsatellite DNA) and phenetic (geometric morphometrics) markers on the same specimens. Using these same markers, we also compared these samples with specimens from a more distant area of south Ivory Coast, the region of Aniassue (186 km north from Abidjan). Results: Neither genetic nor phenetic markers detected significant differentiation between the three Abidjan G. p. palpalis samples. Thus, the null hypothesis of a single panmictic population within the city of Abidjan could not be rejected, suggesting the control strategy should not consider them separately. The markers were also in agreement when comparing G. p. palpalis from Abidjan with those of Aniassue, showing significant divergence between the two sites. Conclusions: Both markers suggested that a successful control of tsetse in Abidjan would require the three Abidjan sites to be considered together, either by deploying control measures simultaneously in all three sites, or by a continuous progression of interventions following for instance the "rolling carpet" principle. To compare the geometry of wing venation of tsetse flies is a cheap and fast technique. Agreement with the microsatellite approach highlights its potential for rapid assessment of population structure
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