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Intended as guide for designing the fertilization system in oil palm plantations, this book explains in clear language how to define fertilizer recommendations for each plantation, considering the specific characteristics of each site. The authors present the principles for interpreting the results of plant tissue analysis, mainly leaflets, taking into account the influence of factors specific to each plantation (age, plant material, climate, soil). They detail how to experimentally determine site-specific reference levels of mineral elements and sampling rules for monitoring the nutritional status of the plantation. Priority is given to the most specific facies (soil, plant material) of the planted areas rather than to an average representation of the plots. This guide explains how to create fertilization schedules to achieve optimal leaf contents from experimentation, and to compare these data with information from geographic information systems. This decision support system is designed to be valid in all situations. In addition to the economic optimization of fertilization, environmental concerns are considered: soil health and absorption efficiency must be integrated into the fertilization strategy by optimizing cultivation practices for fertilizer application and organic matter management. This guide is illustrated by numerous examples from trials in various soil, climate and plant material conditions in Africa and Latin America.

We compared four oil palm (Elaeis guineensis Jacq.) progenies’ morphological growth characteristics to reveal genotypic differences in plant growth and assess their adaptability in Nigeria’s environment in response to different levels of potassium chloride (KCl) and kieserite fertilizer applications. The studied progenies (C1, C2 and C3 of Deli × La Mé origin and C4 of Deli × Yangambi origin) represent a wide genetic diversity of oil palm and have shown among a population of 116 different progenies, a contrasting K and Mg leaflet concentrations that covered the extreme ranges of leaflet concentrations in these minerals. The trial consisted of a completely randomized split-plot factorial design with six replicates, where progenies, considered as sub-factor were treated with combinations of 3 levels of potassium chloride (0, 1.5, 3.0 kg of KCl palm−1 year−1) and kieserite (0, 0.75, 1.5 kg of MgSO4 palm−1 year−1) fertilizers (main factor), respectively. Growth characteristics differed significantly among progenies, but not in all studied years. In all progenies, KCl treatments significantly increased the average annual collar girth increment and projected canopy area. Adding 3.0 kg palm−1 year−1 of KCl significantly increased the total leaf area of progeny C4. Kieserite applications did not have an effect on progenies’ growth characteristics whereas potassium showed to be the main mineral needed for oil palm growth. It was shown that with equal amounts of fertilizers applied, progeny C3 had better morphological traits than the other progenies, suggesting that the effective nutrient requirements should be assessed for each individual progeny and that fertilization should be adapted accordingly.

Oil palm fertilizer requirements are based on leaflet mineral concentrations. Four oil palm progenies representing a wide genetic diversity of Elaeis guineensis species and with contrasting K and Mg leaflet concentrations were tested in Indonesia and Nigeria, environments which differ predominantly in climate. During 5 years, we compared oil palm progenies’ leaflet mineral concentrations between both countries under abundant fertilizer applications to investigate the extent to which they depend on the environment. In the two studied environments, leaflet concentrations significantly differed between progenies for K, Mg and Ca, but the country effect was not found significant (p = 0.352) for any leaflet mineral’s concentration. In both countries, progenies ranked similarly in their mineral categories (lowest and highest cation concentrations within the 4 progenies population), indicating that leaflet mineral concentrations in the tested oil palm progenies are mainly determined by their genetic background. For each progeny, with abundant fertilization, K, Mg and Ca proportions to total leaf cation charge (TLCC) were similar, irrespective of the environments in which the palms were cultivated. We have strong indications that foliar concentrations of K, Mg and Ca are determined by genetic factors which dominate the environmental effect. However, it remains uncertain whether differences in oil palm foliar concentrations between different oil palm progenies imply that they require specific fertilizer amounts to attain an optimal production.

Background and aims: In oil palm, similar fertilization treatments can result in leaflet potassium and magnesium concentrations that vary significantly from one progeny to another. This hinders the development of standardized fertilizer recommendations for this crop, as they are usually calculated based on optimum leaflet nutrient concentrations.Methods: 4-high-yielding oil palm progenies with contrasting leaflet K and Mg concentrations (C1, C2, and C3 of Deli x La Mé origin and C4 of Deli x Yangambi origin) were treated with combinations of 3-levels of KCl and MgSO4, in a completely randomized split-plot factorial design with 6-replicates, where progenies were a sub-factor.Results: For a given level of KCl or MgSO4, different leaflet K and Mg concentrations were found between progenies (p < 0.0001). Leaflet K concentration and yield response to KCl applications revealed that the four oil palm progenies have different optimum leaflet K concentrations. In our study period (5-8 YAP), progenies C1 and C3 showed their highest fresh fruit bunch (FFB) yields (13.62 and 16.54 t ha-1 year-1, respectively) at K2, whereas progenies C2 and C4 showed their highest yields (14.62 and 12.39 t ha-1 year-1, respectively) at K1. Conclusion: Our study highlighted specific optimum leaflet K and Mg concentrations for different oil palm progenies in a given environment. It paves the way for adopting K and Mg fertilizer application rates adapted to specific requirements of each type of oil palm planting material.

Minyak kelapa sawit adalah minyak nabati yang paling banyak dikonsumsi dunia. Setengah dari produksinya berasal dari Indonesia, walaupun perluasannya telah dikritik dari sudut pandang lingkungan. Pengurangan dampak lingkungan perkebunan melalui praktik pengelolaan limbah yang lebih baik sangat penting untuk mencapai produksi yang lebih bersih. Dalam konteks ini, penelitian difokuskan pada pengomposan, praktik yang semakin banyak diterapkan di agroindustri. Penelitian bertujuan untuk menguji pengomposan produk samping pabrik kelapa sawit yaitu tandan kosong kelapa sawit ( TKKS ) dan limbah cair pabrik kelapa sawit ( LCPKS ), pada rasio LCPKS / TKKS dan frekuensi pembalikan yang berbeda. Setelah 60 hari, kompos masih dalam fase mesofilik dan tidak dapat dianggap sebagai kompos matang karena rasio C/N dan suhu yang tinggi. Penurunan bobot dan volume yang tinggi telah dicapai masing-masing sebesar 40% dan 60%, serta penguapan air yang signifikan dari LCPKS dan TKKS (60%). Rasio LCPKS terhadap TKKS pada 1 – 1.5 m 3 /ton adalah optimal untuk mencapai kelembaban (65-70%), ruang udara bebas (>50%) dan pemulihan nutrisi, juga menunjukkan bahwa dalam kondisi percobaan ini proses pengomposan tidak dapat menggunakan semua LCPKS yang diproduksi oleh pabrik (3m 3 /ton TKKS ). Tingkat pemulihan nutrisi mendekati 100% untuk fosfor, kalium dan magnesium, sedangkan untuk nitrogen terjadi kehilangan sekitar 30-35%. Pengomposan dengan platform beton dan beratap, tidak melakukan penyemprotan pada tumpukan secara berlebihan, dan mendaur ulang semua limbah cair merupakan hal penting untuk mencapai efisiensi pemulihan nutrisi yang tinggi dan untuk mengontrol kualitas kompos akhir. [Kata kunci : pengomposan, tandan kosong, pemulihan nutrisi, kelapa sawit, limbah cair pabrik kelapa sawit, keberlanjutan] Abstract Palm oil is the most consumed edible oil in the world. Roughly half of the production originates from Indonesia, where the expansion of the crop has been criticized from an environmental perspective. Reducing the environmental impact of plantations through better waste management practices is critical to achieve cleaner production. In this context, our study was focused on composting, a practice increasingly adopted among agro-industries. Our trial was designed to test co-composting of the main palm oil mill by-products – empty fruit bunches (EFB) and palm oil mill effluent (POME) – under different POME/EFB ratios and turning frequencies. After 60 days the compost was still in a mesophilic phase and could not be considered as mature compost due to high C/N ratio and temperature. High weight and volume reduction were achieved (40% and 60% respectively), as well as significant water evaporation from the POME and EFB (60%). We found that a POME to EFB ratio of 1 to 1.5 m 3 /ton was optimal for moisture (65-70%), free air space (>50%) and nutrient recovery, showing that in our experimental conditions the composting process could not use all the POME produced by the mill (3m 3 /ton of EFB). The nutrient recovery rate was close to 100% for phosphorus, potassium and magnesium. For nitrogen we observed 30-35% of losses. Composting on a concrete platform with a roof, not over-spraying the piles and recycling all the leachates are critical points to achieve high nutrient recovery efficiency and to control final compost quality. [Keywords: composting, empty fruit bunch, nutrient recovery, oil palm, palm oil mill effluent, sustainability]

This article follows on from two articles published in 2014 and 2018 on the same trial conducted in an oil palm plantation in Nigeria which was aimed at assessing a range of different planting distances between oil palms (7.5 to 9.5 m) in an equilateral triangle design. The climate in the region is very stable, with two seasons and an average 2000 mm of rainfall per year. The soil is of the desaturated ferralitic type, sandy on the surface, deep, and without coarse elements. After continually monitoring the experimental palms for 16 years, there is now enough hindsight to propose an optimum planting density for oil palms in Western Africa. A plateau has been reached at between 143 and 160 palms per hectare for Pobè C1001F material in the aforementioned pedoclimatic context.

Guide d'aide a la conception de la fertilisation des plantations de palmier a huile, cet ouvrage expose dans un langage clair comment definir dans chaque plantation les recommandations d'engrais qui prennent en compte les specificites de chaque site. Les auteurs presentent les principes d'interpretation des resultats d'analyse des tissus vegetaux, principalement les folioles, en tenant compte de l'influence des facteurs propres a chaque plantation (âge, materiel vegetal, climat, sol). Ils detaillent comment on determine experimentalement les teneurs de reference en elements mineraux specifiques de la plantation et les regles d'echantillonnage pour suivre l'etat nutritionnel de la plantation. La priorite est donnee aux facies (sol, materiel vegetal) les plus specifiques des surfaces plantees plutot qu'a une representation moyenne des parcelles. Ce guide explique comment creer des baremes de fertilisation pour atteindre les teneurs foliaires optimales tirees de l'experimentation, et confronter ces donnees a des informations issues des systemes d'information geographiques. Ce systeme d'aide a la decision est concu pour etre valable dans toutes les situations. Au-dela de l'optimisation economique de la fertilisation, les preoccupations environnementales sont prises en compte : la sante des sols et l'efficience de l'absorption doivent etre integrees dans la strategie de fertilisation en optimisant les pratiques culturales pour l'application des engrais et la gestion de la matiere organique. Ce guide est illustre par de nombreux exemples issus des essais dans des conditions variees de sol, de climat et de materiel vegetal en Afrique et en Amerique latine.

SUMMARYPotassium chloride (KCl) is the most widely used fertilizer in oil palm (Elaeis guineensis) plantations and the rates applied are based on interpretation of leaf K contents. When no positive response on leaf K contents can be detected, no optimum content can be established whatever the yield response to KCl rates. We used data from 13 fertilization trials conducted on several continents to study the responses of leaf K, leaf Cl, leaf Ca and yield to KCl rates as a function of the soil properties of each site. We found that the abundance of exchangeable Ca in the soil expressed as a percent of the cation exchange capacity (CEC) was the best soil variable to predict if leaf K content would increase with KCl rates. In addition, we found that the leaf K contents of unfertilized controls at the end of the trials were also correlated with Ca/CEC. This ratio thus appears to be a better index of soil K reserves than soil exchangeable K content.

This article follows on from an earlier one about the same experiment in 2014. A range of various planting distances (from 7.5 to 9.5 metres) between oil palms was tested using an equilateral triangle design. The current planting density experiment was set up in an oil palm plantation in Nigeria. The climatic conditions are quite stable, with two seasons and around 2000 mm of annual rainfall. The soil is of the desaturated ferralitic type, sandy on the surface, deep and without coarse elements. After twelve years of continual monitoring and extrapolation of the results obtained up to the end of the cycle, we concluded on an optimum planting density of between 143 and 160 oil palms per hectare in a monospecific, equilateral triangle planting design (i.e. a distance of 8.5 to 9 metres between palms). It will take another few years of yield recording to fine-tune the result. For 12-year-old palms, this density range corresponds to a Leaf Area Index of 3.5 to 4, a light interception percentage of 89 to 90 and a foliage overlap percentage of 51 to 68. A thinning treatment was included in the protocol. Thinning at eight years has not led to any advantage after four years.

International audience; Palm oil is nowadays the first vegetable oil consumed worldwide. Given the world population growth and the increasing demand in fat for food and fuel, the increase in oil palm production is expected to continue. It is thus important to find ways of reducing the ecological impact of oil palm plantations at both the agroecosystem and the mill supply area levels, by improving agricultural practices and land uses. This is where agroecology can play a very critical role. The present article gathers short stories on agroecological practices currently taking place in oil palm plantations in South-East Asia. Such stories notably highlight the importance of the various palm co-products and how appropriate recycling strategies can allow for reducing external inputs to both the field and the mill. Besides limiting environmental impacts thanks to such savings, several co-products used as organic amendments can even help to maintain or enhance soil quality. Other stories explored agroecological practices developed for biological controls. Although integrated pest management has been applied in palm plantations for a long time, the underlying mechanisms are still not fully deciphered and practices still need to be improved. More knowledge is needed in order to better account for the holistic role of biodiversity and arbitrate trade-offs between practices and ecosystem services, at both plantation and landscape levels.; L'huile de palme est aujourd'hui la première huile végétale consommée au monde. Étant donné la croissance démographique mondiale et la demande accrue en corps gras pour l'alimentation et les biocarburants, l'augmentation de la production d'huile de palme devrait perdurer. Il est ainsi primordial de trouver des moyens de production permettant de réduire l'impact écologique des plantations de palmier à huile, à la fois à l'échelle de l'agroécosystème et celle du bassin d'approvisionnement de l'huilerie, en améliorant les pratiques et la gestion des usages des sols. Les principes de l'agroécologie peuvent aider à développer des solutions à ces diverses échelles. Cet article rassemble diverses histoires courtes illustrant des pratiques agroécologiques mises en place dans des plantations de palmier à huile en Asie du Sud-Est. Ces illustrations mettent en évidence l'importance des nombreux co-produits issus du palmier et leur rôle clé dans les stratégies de recyclage pour réduire le recours aux intrants externes pour la plantation comme pour l'huilerie. Au-delà de la réduction des impacts environnementaux du fait de ces économies d'intrants, certains co-produits restitués en plantation peuvent également permettre de maintenir, voire d'améliorer, la qualité des sols. D'autres histoires courtes parcourent quelques autres pratiques agroécologiques dans le domaine de la lutte intégrée. Bien que de nombreuses pratiques de contrôle biologique soient mises en œuvre dans des plantations de palmier à huile depuis de nombreuses années, les mécanismes sous-jacents ont été encore peu explorés et les pratiques peuvent être améliorées. De nouvelles connaissances sont nécessaires pour mieux caractériser et prendre en compte de manière holistique les enjeux et le rôle de la biodiversité et pouvoir arbitrer les compromis entre pratiques et services écosystémiques, aux échelles de la plantation et du paysage.

Predicting the fertilizer requirements of an oil palm plantation has long been a difficult task. Two main methods have emerged. Leaf analyses (LA) were used for fertilization management as early as the 1950s. Leaf contents are compared to optimum references, making it possible to adjust the fertilizer rates applied in each block. Another approach, based on the nutrient balance (NB), is to evaluate and replace nutrients that are exported from the field, or immobilized by the plant. Plantations must adopt environmentally friendly practices; in particular, fertilizer inputs must be estimated with sufficient precision to achieve the highest possible yields, without applying excessive amounts of nutrients in relation to plant demand and the storage capacity of soils. We questioned the relevance of each method for achieving these objectives. We did so using some long-term fertilization trials to compare the optimum N and K rates recommended by each method in the adult phase. It appeared that LA led to moderate rates compared to NB. It also appeared that calculating a precise nutrient balance on a field scale was hampered by a lack of precise information (i) about the biomasses produced and their composition and (ii) about the highly variable outputs of the environmental losses. On the other hand, LA provided a simple indicator of the ability for each block to achieve its potential yield. We believe that this perfectible method is more protective of the environment, without the risk of a significant decrease in yields or a decrease in soil mineral reserves.

We demonstrated experimentally that Sufetula, a root-mining insect, has a depressive effect on coconut yields on peat soils. The impact of the pest resulted in a shortfall in earnings that warranted taking control measures. We considered control methods suitable for rehabilitating infested mature coconut plantings and for preserving young coconut plantings. Currently, cultural control is the only effective method. It involves eliminating all identified shelters for the adult insect, i.e. fern cover and heaps of coconut waste (dry fronds and husks). The aim is to achieve totally bare soil, with moss cover that does not attract the pest, or planted with an unattractive intercrop such as pineapple.

The effects of chlorine and potassium on the leaf morphology of 6-year-old PB 121 hybrid coconut palms were studied in 1995 and 1996 in southern Lampung (South Sumatra, Indonesia). The parameters considered were frond and leaflet size (length, maximum width, area) and their number. Chlorine and potassium had an exclusive effect on leaflet size, increasing their area. Potassium primarily affected petiole length, hence total frond length. Synergy between these two ions only occurred for the number of leaflets. Chlorine and potassium acted independently on stem diameter and synergistically on height Coconut palms receiving potassium or chlorine had significantly more voluminous leaf crowns. As time went by, this phenomenon increased despite constant monthly leaf emission. In a situation of equilibrium, the much larger mean crown area and leaf area index of coconuts receiving chlorine and potassium augured well for an earlier start to bearing and higher nut yields. (Resume d'auteur)

The nut yield and fruit composition of 'nature (30-40 years old) West African Tall coconut palms were evaluated in seven trials during the first three years (from June 2000 to May 2003) of implementation of a five-year fertilization schedule recommended to the Coconut Sector Development Project (CSDP) for the rehabilitation of old farms in the coastal belt of the Western Region of Ghana. The seven trials are located at Jeway Wharf, Takinta, Ellenda, Nawule, AB Bokazo, Anwia and Edwakpole. Three fertilizer treatments were applied between June 2000 and May 2003. The first two fertilizers were applied in June 2000 and May 2001 at the rate of 0. 75kg urea and 2.5kg muriate of potash (MOP) per palm. For the third fertilization, 1 kg MOP only was applied per palm in May 2002. Fertilizer treatment did not affect nut yield in year one of fertilization. But in year two, the fertilized plots gained remarkably 27.7, 20.2, 19.4 and 14.9 nuts per palm at Jeway Wharf, Nawule, Ellenda and Takinta respectively. The remarkable nut gain was further boosted or sustained in year three except at Jeway wharf which lost 9.8 nuts per palm. In economic terms, Ellenda trial broke even on MOP fertilizer investment in year three while Jeway Wharf was close to breaking even. Takinta and Nawule trials made profits of 925 and 1, 750 cedis (3.7 and 7 nuts) per palm respectively in year three. For Anwia, AB Bokazo and Edwakpole trials there was no yield response to MOP fertilizer due to P deficiency. Fertilizer treatment in the first two years of fertilization did nor influence fruit composition. (Resume d'auteur)

Dans la plupart des pays producteurs, la population de cocotiers vieillit et les moyens visant a leur remplacement sont rarement mis en oeuvre pour assurer le maintien de la production et sauvegarde l'avenir de l'industrie et sa rentabilite. La rehabilitation/replantation des cocoteraies et l'adoption de systemes de cultures associees adaptes est l'un des principaux defis a relever pour l'avenir du cocotier dans la region Asie - Pacifique. L'exemple de la Papouasie-Nouvelle-Guinee (PNG) montre l'un des plus faibles rendements a l'hectare parmi les pays de la zone Asie-Pacifique. On denombre pres de 106 000 ha plantes entre 1910 et 1940, representant environ 40% de la cocoteraie, et on peut donc envisager la disparition de 80 a 100 000 ha dans les vingt prochaines annees. Face a cette prevision, l'Institut de Recherche sur le Cacao et le Cocotier de PNG (CCRI) a entrepris plusieurs actions a partir de la creation d'un centre de recherche cocotier sur la Grande Terre de PNG : etude d'une strategie de replantation des vieilles cocoteraies a partir de materiel vegetal hybride, diffusion de materiel vegetal ameliore a partir de la creation d'un champ semencier et mise au point d'un outil de lutte pour controler les populations de ravageurs dans les zones a haut risque. L'experimentation mise en place sur station vise a optimiser la date d'abattage des vieux arbres en mesurant les effets de competition avec les hybrides complantes, et a determiner d'un point de vue economique la meilleure strategie a appliquer pour la mise en place de programmes de rehabilitation et/ou de replantation des cocoteraies âgees. Les resultats de ces actions sont presentes dans cette communication. (Resume d'auteur)

A range of various different planting distances (from 7.5 to 9.5 m) between oil palms were tested using an equilateral triangle design in a plantation density experiment which was settled in an oil palm commercial plantation in Nigeria. Climatic conditions were quite stable, with two seasons and around 2000 mm of annual rainfall. The soil was of desaturated ferralitic type, sandy on the surface, deep and without coarse elements. The early impact of plantation density was analysed at eight years after planting. Some early signs of depressive effect on yields were found for high planting densities (180 and 205 p/ha). Such a negative impact was not severe enough to counteract the effects of a higher number of palms per hectare. As a consequence, a gradient could be observed as yields (in tons of bunches per hectare) increased with density. We can anticipate that the competition effect between palms will increase over time with high densities, so that the counteracting point ought to be reached in a few years. A thinning treatment has been included in the protocol. Thinning was carried out at the end of the eight-year period.

SUMMARYOver several decades agronomists have developed a mineral nutrition management method for perennial oil crops based on leaf analysis combined with reference field trials. This method has been used in a coconut plantation on the peats of the east coast of Sumatra to optimize mineral nutrition in a very short time, at minimum cost and with maximum reliability, through successive adjustments of the fertilizer schedules. Two reference trials were set up to study a wide range of mineral nutrients assumed to be deficient on this area. Further experiments were set up as new nutritional problems occurred at the plantation, and as soon as the first results were obtained from these two trials. In this way, the iron and copper deficiency problems at the plantation were dealt with satisfactorily taking an experimental approach. New experiments were set up recently to test the hypothesis of a silicon deficiency. The fertilization schedules for the commercial plantation were developed by successive adjustments based on the trial results. Leaf analysis data showed that the coconut palms in the commercial plots always complied with the experimental models. In addition to being rapid and reliable, this method was also cost-effective, especially when larger areas were involved.

On a large coconut plantation planted on a deep peat soil in Sumatra, Indonesia, hybrid coconut yields are stabilizing at values well below their potential, even in plots where known production factors have been mastered since the outset: land preparation, water control, and mineral fertilization. To explain this situation, five hypotheses have been proposed. They were tested one by one in field trials. The authors have demonstrated that the main reason for stabilized yields was the Lepidoptera root pest Sufetula spp. and conclude by considering lines of research for controlling this pest in the context of rehabilitation and replanting.

The study of interactions between cacao (Theobroma cacao) and coconut (Cocos nucifera) in Lampung, Indonesia, examined different combinations of age, plant lay-out, planting chronology and choice of planting material under changing environmental conditions. Four coconut-cacao intercropping trials were used to assess the performance of each intercrop under limiting or non-limiting environmental conditions. In intercropping experiments with young cacao trees and young coconut palms, delayed cacao tree development and reduced yields were observed. When coconut palms were aged five years or over, coconut and cacao growth were satisfactory under virtually normal environmental conditions; death rates remained reasonable and yield percentages differed little from those of the monocultures for each crop. The performance of both plants, however, changed when water became a limiting factor.

La culture du cocotier, traditionnelle dans les pays du Pacifique Sud, a pris son essor au cours de la période coloniale. En Papouasie-Nouvelle-Guinée, par exemple, la superficie plantée en cocotiers est passée de 16 000 ha en 1909 à quelque 105 000 ha au début de la Seconde Guerre mondiale. Après la guerre, la plantation de cocotier s’est intensifiée en milieu villageois pour porter la superficie totale actuelle à 260 000 hectares [1]. Devenant sénile, une bonne partie de cette superficie de cocoteraie est laissée à l’abandon car elle ne procure plus une source viable de revenus pour les exploitants. On peut donc s’attendre à voir disparaître 80 000 à 100 000 ha de cocoteraies au cours des vingt prochaines années dans ce pays. Le programme de recherche en agronomie et sur les systèmes de culture basé à Stewart Research Station a entrepris il y a quelques années l’étude des différentes voies possibles permettant d’améliorer et de diversifier les revenus par unité de surface.

Une etude des echanges gazeux foliaires en saison seche et en saison humide, a confirme l'importance du role de l'ion chlorure chez le cocotier. En saison seche, par rapport a un temoin, la carence en chlorure entraine des conductances stomatiques plus faibles qui conduisent a la diminution des echanges gazeux. Il en resulte une photosynthese et une transpiration moins intenses, expliquant la moins bonne tolerance a la secheresse du cocotier carence. En saison seche, meme peu intense, un cocotier non carence, maintient et meme augmente sa conductance. Ceci permet d'accroitre sa transpiration, de repondre a l'augmentation de la demande evaporative et de maintenir une photosynthese elevee. Au contraire, les plants carences diminuent leur conductance, provoquant une baisse de transpiration et photosynthese. Des observations en saison des pluies n'ont pas mis en evidence un effet d'une carence en chlorure sur la photosynthese intrinseque du cocotier. L'ion chlorure semble intervenir essentiellement en saison seche, et sur la regulation stomatique (Resume d'auteur)

Evaluation of four coconut management options was carried out from May 1999 to May 2004 in the coconut belt of the Western and Central Regions of Ghana for replanting of coconut plantations devastated by the Cape St Paul Wilt Disease of Ghana. Coconut hybrid identified for the replanting was MYD x VTT. On fertile soils just intercropping of inter-rows with food crops proved appropriate for managing the coconut hybrid successfully. On low fertile soils however, fertilization was required in addition to intercropping for proper management of the hybrid. Where intercrops were fertilized the coconut palms benefited from the residual effect. While Pueraria phaseoloides did not have any visible impact, Cassia siamea was antagonistic to growth and development of the young coconut hybrid. Fertilized intercropping was more profitable especially on low fertile soils. (Resume d'auteur)

Copra yield in Papua New Guinea is estimated at 0.6 tonnes per- hectare per year. Several factors may be responsible for this low productivity compared to other Asia Pacific countries. Amongst these, nutrient deficiency is an important limiting factor. In order to evaluate coconut nutrition status in PNG, leaf sample collection was undertaken by examining 23 sites around the country and from a nutrition trial carried out at the Stewart Research Station of the PNG Cocoa and Coconut Research Institute (PNG-CCRI) in the Madang Province. Results of 1eaf analysis revealed significant widespread nitrogen deficiencies at most of the sampled sites and geographic variations in potash deficiency. Chlorine deficiency varied with geographic sites and was closely related to the prevailing wind pattern. Preliminary results on nut-set and flowering in the trial at Stewart Research Station revealed a positive response to nitrogen and chlorine-based fertilizer applications. This suggests that appropriate fertilizer applications would be benefit future coconut production on this particular site. (Resume d'auteur)