Effects of peach or hybrid rootstocks on growth and cropping of two cultivars of peach trees (Emeraude and Zephyr).Abstract - Introduction. Rootstock is an important consideration for a productive peach orchard, especially in a replanting situation. A peach and two hybrid rootstocks, grafted with an early and a late-season peach cultivar, were planted and their growth compared. The experimental area had been used since 1970, for two generations of successive peach crops. Materials and methods. Emeraude (early-season) and Zephyr (late-season) were grafted onto GF 305 (peach rootstock), GF 677 and Cadaman$^{\circledR}$ Avimag (hybrid rootstocks), and were planted in a split-plot experimental design. Fruit yield and vegetative growth were assessed annually. Results. Vegetative growth was greater with the hybrid rootstocks than with the peach rootstock. Fruit production was higher with Cadaman than with GF 677, which was higher than with GF 305. Yield differences associated with rootstocks were greater with Emeraude in comparison with Zephyr, as suggested by the rootstock × cultivar interaction. Discussion. Compared to the previous peach plantation on the same land, the differences observed in this current experiment, between the peach rootstock GF 305 and the hybrid rootstock GF 677, widened, suggesting a replanting decline with the peach rootstock. In the given conditions, the hybrid rootstock Cadaman appeared to be better suited than GF 677 to improving peach production.

Introduction. This protocol aims at (a) evaluating the resistance to post-harvest diseases within different genotypes of bananas, and (b) comparing different origins of bananas (geographic origin, physiological stage, etc.) for their susceptibility to post-harvest diseases. The principle, key advantages, starting plant material, time required and expected results are presented. Materials and methods. Materials required and details of the twelve steps of the protocol (fruit sampling and inoculum preparation, wound anthracnose resistance study, quiescent anthracnose resistance study and crown-rot resistance study) are described. Results. Typical symptoms of the different diseases are obtained after artificial inoculation.

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

Introduction. Biennial bearing and malformation are the two present problems of mango which are threatening the very existence of a global mango industry in India. Many factors are closely associated with these problems but, presently, those really responsible are not known exactly. Polyphenol oxidase (PPO) plays vital roles in higher plants and, hence, its activity was measured in swollen buds at panicle initiation in regular and biennial bearing mango cultivars to establish a relation between the PPO activity and the flowering behaviour or the malformation incidence. Materials and methods. Six regular (Sensation, Eldon, Tommy Atkins, Amrapali, Neelum and Bangalora) and six biennial bearing cultivars (Langra, Chausa, Edward, St. Alexandrina, Extrema and Bombay Green) were studied. PPO activity was measured in fully swollen buds by preparing a crude enzyme extract at 4 °C. Catecholase activity was measured by using 4-methyl catechol (4-MC) as the substrate, while 4-methyl phenol (p-cresol) was used for cresolase. Results and discussion. Both catecholase and cresolase activities were higher in the swollen buds in the year 2000 than in 1999. Regular bearers exhibited low PPO activity and showed the higher incidence of malformation as compared to the biennial bearing cultivars.Whatever their type of production, cultivars exhibited significant variations in PPO activities and malformation incidence. Conclusion. A strong negative correlation between PPO activity and number of panicles, and PPO activity and malformation incidence, suggests that the PPO activity is inversely related to both flowering and malformation incidence in mango.

Introduction. Le safoutier (Dacryodes edulis, Burseraceae) est un arbre dont les fruits sont très appréciés par les populations de son aire de répartition. Plante allogame, la multiplication par semis ne permet pas d'effectuer une multiplication conforme de l'arbre sélectionné. La présente étude a eu pour principal objectif de mettre au point une technique de régénération in vitro des bourgeons axillaires et apex prélevés sur de jeunes plants issus de la germination de graines, afin d'adapter ultérieurement cette technique au clonage d'arbres adultes par utilisation de repousses formées après recépage. Matériel et méthodes. Des nœuds et apex prélevés sur des plants de Dacryodes edulis issus de la germination de graines ont été mis en culture in vitro sur un milieu Murashige et Skoog dilué de moitié (MS 1/2). Les effets du charbon actif et de la benzyleadéninepurine (BAP) sur le débourrement des explants ont été étudiés, de même que l'influence de l'acide naphtalènacétique (ANA) et de la photopériode sur l'enracinement. Résultats. Le milieu MS 1/2 additionné de charbon actif à 2g × L-1 et de BAP à 2,22 µM ou 4,44 µM a provoqué le meilleur débourrement des bourgeons axillaires et une bonne croissance des tigelles. L'ANA à 5,37 µM a favorisé l'enracinement. Une période de 7 j à l'obscurité s'est révélée favorable à l'induction racinaire. Deux types de racines ont été observés : les racines néoformées (issues de cals) et les racines adventives. L'acclimatation a été faite avec succès sur substrat constitué de tourbe et vermiculite. La régénération des vitroplants à partir des nœuds et apex permet de distinguer le long de la jeune plante un gradient morphogénétique acropétale. Discussion et conclusion. Ces résultats pourront être exploités pour la mise au point d'une micropropagation conforme à partir de jeunes repousses formées après la taille d'un safoutier présentant des caractéristiques intéressantes.

Introduction. This rearing technique is applicable to migratory nematodes (e.g., Pratylenchus spp. and Radopholus similis) for mass production of nematodes for experimental purposes, conservation of nematodes, and direct studies of nematodes’ multiplication or reproduction mechanisms. The principle of the method applied, key advantages, starting plant material and time required are presented. Materials and methods. Necessary laboratory materials, and details of the nine steps required for the preparation of carrot discs, preparation of nematodes, inoculation of nematodes and collection of nematodes out of petri dishes are described. Possible troubleshooting is explained. Results. Several thousands of nematodes can be extracted out of one carrot disc after 6–8 weeks of culture, depending on nematode species and geographical population.

Introduction. Les réactions d’oxydation constatées régulièrement dans les aliments peuvent causer des dommages importants, entraînant parfois des cancers et maladies chroniques. Les extraits d’huiles essentielles étant connus pour posséder d’importantes propriétés thérapeutiques, notre étude a cherché à comparer les activités antiradicalaires et anti-inflammatoires des essences de C. reticulata var. Madagascar et C. sinensis var. Casagrande. Matériel et méthodes. Les huiles essentielles des feuilles d’agrumes ont été extraites par hydrodistillation et leur composition chimique a été analysée par chromatographie en phase gazeuse et par chromatographie en phase gazeuse couplée à la spectrométrie de masse. La détermination des propriétés antiradicalaires a été faite par la méthode du piégeage des radicaux libres à l’aide du diphenyl picryl hydrazyl (DPPH). En revanche, la méthode enzymatique par la lipoxygénase a permis d’évaluer l’activité anti-inflammatoire des extraits d’huiles essentielles obtenues par hydrodistillation. Résultats. Les propriétés antiradicalaires de nos échantillons ont été évaluées avec une SC50 égale à (4,10 ± 0,05) g·L–1 et (7,40 ± 0,55) g·L–1, respectivement, pour C. reticulata var. Madagascar et C. sinensis var. Casagrande, alors que le composé antiradicalaire de référence (butylhydroxytoluène ou BHT) donnait une SC50 de (7,02 ± 0,5) mg·L–1. Par ailleurs, les deux échantillons ont montré une activité anti-inflammatoire exploitable (IC50 de 53,5 mg·L–1 et 20,3 mg·L–1, respectivement) même si le NDGA (acide nordihydroguaiarétique) a eu une IC50 de 0,7 mg·L–1. Conclusion. C. reticulata var. Madagascar se révèle avoir une activité antiradicalaire plus importante que C. sinensis var. Casagrande, alors que cette dernière espèce a présenté l’activité anti-inflammatoire la plus marquée. Ces huiles essentielles pourraient être utilisées comme additifs alimentaires.

Introduction. Two Turkish fig cultivars, Alkuden and Bursa Siyahi, were propagated by meristem culture to eliminate the fig mosaic virus. The technique of dsRNA analysis was conducted on the in vitro propagated plants to test for virus-free status. Materials and methods. Four different Murashige and Skoog (MS) media complementedwith different concentrations of growth hormones (GA3, BA and IBA) were compared to study the cultured meristems’ survival rate, shoot formation and rooting. Short- and long-term thermotherapy treatments were also applied. Results. For survival rate, 0.2 mg GA3·L–1 + 0.5 mg BA·L–1 gave the most favorable results; for shoot formation, it was the medium with 0.2 mg GA3·L–1 + 2.0 mg BA·L–1 which was the best, while rooting rate was the highest for meristems cultured on MS medium with only 0.1 mg GA3·L–1. Conclusion. Meristem culture, together with thermotherapy treatment, is recommended to obtain virus-free fig plant material. Although cultured plants seemed to be very healthy, dsRNA virus tests are recommended for sensitive evaluation of the sanitary status of the plants obtained.

Introduction. One of the challenges of the Malaysian pineapple industry is to develop new techniques for managing pineapple residues. A study was carried out to investi- gate whether K-humate can be produced from these residues. Materials and methods. Pineapple leaves were air-dried, shredded and chipped. Some of the shredded leaves were incinerated at 500 °C. Potassium hydroxide (KOH) was extracted by dissolving the ash obtai- ned in distilled water for 24 h at a ratio of 1:7 (ash / water) after which the sample was filte- red. After this extraction of KOH from the ashes of pineapple leaf residues, the remaining ash residues were further analyzed to assess the total and soluble K contents. Moreover, a given quantity of shredded leaf residues was mixed with chicken dung (as a source of microorga- nisms and nitrogen) and chicken feed. The mixture was composted with standard procedu- res. Humic acids were reconstituted using KOH from pineapple leaves with K from ash residues and K from composted pineapple leaves. Results and discussion. By reconstituting humic acids with KOH, a K-humate was produced with approximately 34.5% of its K readily soluble in water. A reconstitution of humic acids with K from ash residues produced a K-humate with approximately 3.34% of its K readily soluble in water. Conclusion. The K-humate produced from the reconstitution of humic acids with K from KOH can be used in fertigation programmes as a source of K while the K-humate produced through the reconsti- tution of humic acids with K from ash residues can be used as a source of K for fresh water fishes.

Introduction. High–density orchards of ‘Amrapali’ mango trees become overcrowded and show progressive decline in yield after 14–15 years of planting; hence, trees require pruning for sustainable production. Reduction in yield in such orchards is due to poor light interception and a low photosynthetic rate, which influence vegetative growth, flower initiation, fruit set and, thereby, the fruit yield. Hence, to help design a tree canopy for optimum plant growth and yield, we studied the effect of pruning on light interception and on different leaf physiological parameters of ‘Amrapali’ mango trees under high density. Materials and methods. Sixteen-year-old trees of an ‘Amrapali’ mango high-density orchard were subjected to tipping and light, moderate and heavy pruning; un-pruned trees were used as control. The available photosynthetic photon flux (PPF) and leaf physiological parameters such as rate of photosynthesis, specific leaf weight (SLW) and leaf chlorophyll (Chl) content were measured in pruned and un-pruned tree canopies, following standard procedures. Results and discussion. The percent available PPF was greater in all pruned tree canopies than in un-pruned tree canopies; this could be due to tree openness caused by pruning. The light interception was lower at the lowest height of the tree canopy, probably because the center of the tree canopy was partially blocked by new growth or criss-cross branches. The rate of photosynthesis was greater in leaves that developed in pruned tree canopies than in those developed in un-pruned tree canopies, although there was no difference in SLW; this could be due to better light interception in pruned trees. In contrast, total leaf chlorophyll content was the highest in leaves that developed in un-pruned and tipped tree canopies; this may be due to increased shade owing to overlapping or crowding of tree canopies in these trees, indicating that mango leaves that developed in shade appeared to be more physiologically efficient at synthesizing chlorophyll than leaves that grew in the sun or on the sunny side. Conclusions. The studies indicated that pruning ‘Amrapali’ mango trees by removing about 10–15 cm of the top from old branches improves light penetration, which influences the leaf physiology considerably. Hence, it would be useful for designing high-density ‘Amrapali’ mango orchards to maximize productivity, although it requires additional studies to recommend a particular pruning intensity.

Introduction. Bacterial canker, caused by Pseudomonas syringae pv. syringae, is a devastating disease of stone fruit worldwide. The effects of mineral nutrients and freezing-thawing on bacterial canker susceptibility were evaluated using potted peach trees in an attempt to understand predisposing factors in bacterial canker of stone fruit. Materials and methods. A split-plot experimental design with randomized complete block main plots (i.e., inoculations associated with freezing-thawing or nonfrozen pretreatments) and subplots of trees with the seven treatments (i.e., solutions deficient in N, P, K, Ca, Mg or Fe, respectively, and a full nutrient control) was adopted to study the effect of mineral deficiency and freezing-thawing on peach susceptibility to bacterial canker. Results and discussion. Phosphorus deficiency was the only treatment to significantly decrease lesion length that developed after inoculation with P. syringae pv. syringae, compared with the control trees that received full nutrients. Nitrogen and potassium deficiency treatments significantly decreased bark nitrogen and potassium concentrations accordingly, but had no clear effect on lesion sizes. Inoculation during freezing-thawing cycles significantly increased lesion length. In another independent experiment, nitrogen deficiency significantly increased the number of P. syringae pv. syringae leaf scar infections, but the subsequent infection was limited to a few millimeters. Nitrogen-deficient trees, which had higher [carbon / nitrogen] ratios, developed lesion sizes equivalent to trees provided with full nutrients. Collectively, these data suggest that, in the absence of other major predisposing factors (i.e., low soil pH or ring nematodes), mineral nutrients may play a minor role in the susceptibility of peach to bacterial canker.

Introduction. The causal agent of Panama disease in banana is Fusarium oxysporum f. sp. cubense (FOC). The authors put forward a hypothesis to account for certain disturbances of the natural defence mechanisms of banana plants against Panama disease as a consequence of very low Zn levels which could alter the mechanism of tylose formation. Materials and methods. A long-term experiment was carried out with 2-month-old banana plants in a growth chamber at 23 °C using three different levels of Zn nutrition. The nutrient solutions were inoculated with FOC 1 and FOC 4. Results and discussion. None of the total plants growing in a nutrient solution inoculated with FOC 1 showed infected rhizomes at the end of the experiment, but 75% of the plants growing in pots inoculated with FOC 4 had infected rhizomes. On the other hand, rhizome infection by FOC 4 was influenced by the nutrient solutions. The data showed that the number of plants with damaged rhizomes was significantly higher in the Zn-deficient treatments (100% of plants) than in the normal Zn solution (25% of plants), these internal symptoms being seen to worsen as the presence of Zn decreased in the nutrient solution. Conclusions. The results obtained seem to confirm the role played by Zn nutrition of banana plants in the appearance of Panama disease and are in accordance with our hypothesis concerning the relationships among plant Zn nutrition, plant IAA level, tylose formation and the incidence of the disease. Likewise, under our experimental conditions, race 1 of FOC is confirmed to be non-pathogenic against this banana cultivar, while race 4 is indeed pathogenic.

Introduction. In São Paulo State in Brazil, there is a demand for pear tree varieties that present fruit complementary characteristics and high adaptation for a subtropical-tropical climate. Thus, our study aimed at evaluating variety selections with better fruit quality and mainly adapted to the different areas of the São Paulo State. Materials and methods. Crosses among Asian [Pyrus pyrifolia (Burm.f.) Nakai] and European (P. communis L.) pear cultivars were made in Brazil from 1992 to 1998 aiming at finding new pear types for subtropical areas of the country. The first interspecific hybrids of the IAC pear breeding program were planted in various regions of São Paulo State, at latitudes from 21° 11’ S to 24° 11’ S and (11 to 200) chilling units (CU). About 20 phenological characteristics were evaluated. The hybrids and their parents were genetically characterized through RAPD markers. Results and discussion. In the progeny of ‘Okusankichi’ × ‘D'água’, the mean age for the first bearing and fruit development period (FDP) were 3.8 years and 137 days, respectively. The fruit characters early ripening, rounded shape, russet-brown skin and crisp flesh were dominant in all crosses of Asian × Asian and Asian × European pear trees. Twenty-six hybrids were selected, of which twelve are still being tested in a subtropical-tropical climate (0–80 CU). Their main characteristics are fruit with rounded, oblate, oblong or pyriform shapes, russet-brown or green skin, and crisp or soft flesh, and plants with medium-high vigor, an upright-spreading form and a fruit development period of from (110 to 160) days. Conclusion. The precocity of hybrids is highly dependent on the parental characteristics and the environmental conditions. A fruit development period close to that of the earliest parent was obtained. In F1 generations from crossings among Asian and European pears, certain characteristics were dominant. The RAPD analysis was efficient at identifying cultivar genotypes, selections and hybrids of pear from different botanical groups.

The plant. The aguaje (Mauritia flexuosa L.f.) is an Amazonian palm in the process of domestication to be cultivated as a dwarf form. In Peruvian Amazonia, it has a major impact on the economic, social and ecological systems. Fruit are sold and take part in the economy of Peruvian Amazonia. The insects. In this survey, the authors present 18 species of insect pests observed in eight different localities in the surroundings of the city of Iquitos (Loreto, Peru) between 2000 and 2003. Among those species, four develop in the pulp of the fruit, two are borers of the rachillae, one is a borer of the trunk and the petioles of the young leaves, two species bore the rachillae and floral buds, one develops in buds of female flowers and another damages the base of the roots; eight of those species are considered as the most important pests: Eupalamides cyparissias Fab., Antiteuches kerzhneri Rider, Stenoma sp., Clinodiplosis sp., an unidentified species of Cecidomyiidae, Tyrannion sp. and two unidentified species of Curculionidae. Discussion. The cultivation of the dwarf aguaje is a good alternative to the cutting of the native palms to harvest the fruit, but the cultivated palms are damaged by insects. The planters must learn to know those pests to control them. The biology and the ecology of the new pests are currently being studied.

Introduction. The technology for citrus rootstock production through improved sowing methods and fertilizer inputs offers greater opportunity in the certified citrus plant production system. Our work evaluated the influence of seed coat removal and different controlled-release fertilizer concentrations on plant emergence and plant growth of two citrus rootstock cultivars. Materials and methods. Decoated and not decoated seeds of Rangpur lime (Citrus limonia Osbeck) and Swingle citrumelo [Citrus paradisi × Poncirus trifoliata (L.) Raf] were sown in 50-cm3 tubes. Fertilizer concentrations were (0, 1, 2, 3, 4 and 5) kg·m–3 of controlled-release fertilizer (NPK 19-06-10) incorporated into the substrate. The experimental layout followed a randomized block design with 2 × 6 factorial (seed coat removal × fertilizer concentration) for each rootstock. Results and discussion. Seed coat removal resulted in faster plant emergence and higher dry weight for both rootstocks. Vegetative growth increased with controlled-release fertilizer concentrations.

Introduction. Au Maroc, les agrumes sont confrontés à une combinaison de stress biotiques [virus de la tristeza (CTV) / Phytophthora] et abiotiques (salinité, alcalinité et sécheresse). La plupart de ces contraintes doivent être gérées individuellement par le choix d’un porte-greffe adapté. Cependant, la propagation de la CTV dans le bassin méditerranéen va bientôt interdire l’utilisation du bigaradier, porte-greffe traditionnel, qui offre actuellement une tolérance suffisante à la salinité et l’alcalinité. Par conséquent, la sélection de nouveaux porte-greffes d’agrumes devient pressante. Notre étude a cherché à étudier l’effet de différents régimes hydriques sur la croissance de dix porte-greffes d’agrumes : citrange Carrizo (France), citrange Carrizo (Maroc), citrange Troyer, citrange Yuma, Citrus volkameriana; deux Poncirus trifoliata d’origine différente, citrumelo, Mand. Sunki  ×  Poncirus trifoliata, et Poorman. Matériel et méthodes. Pour chaque porte-greffe, des plants âgés de trois mois ont été cultivés en pots de plastique (0,5 L) dans une serre à El Menzeh, INRA, Maroc; ils ont été soumis à trois régimes hydriques [(100 %, 75 % et 50 %) d’humidité à la capacité au champ (Hcc) du substrat]. L’expérimentation a été disposée en un split-plot à trois traitements. Les paramètres morphologiques mesurés ont été la hauteur de la plante et l’accumulation de matière sèche et fraîche. Les paramètres physiologiques étudiés ont été la teneur relative en eau, le taux de transpiration et les teneurs en chlorophylle, sucres solubles et proline. Résultats. Les paramètres morphologiques et physiologiques ont été affectés par l’intensité du stress hydrique appliqué. Cependant, les porte-greffes se sont comportés différemment vis-à-vis de cette contrainte. Le stress hydrique a induit une augmentation de la teneur en proline et en sucres solubles au niveau des feuilles des porte-greffes. Conclusion. Le stress hydrique affecte d’une manière significative les caractéristiques physiologiques et morphologiques des porte-greffes d’agrumes et, en conditions de déficit hydrique extrême (50 % Hcc), un comportement différentiel des porte-greffes a été constaté. Sur la base des résultats que nous avons obtenus, ce sont les porte-greffes citrange Carrizo (Maroc) et Poorman qui présenteraient globalement les meilleures aptitudes à résister aux conditions de stress hydrique.

Introduction. Insect pest identification and understanding of insect pest ecological relationships constitute a basic step for any control measure needed. Some native fruit trees occur naturally in southern Mozambique and the edible fruits are sought after by local communities. Our study aimed at assessing the activity of native fruit tree insect pests during the year and their ecological relationships, providing, for the first time, a faunistic analysis of insect species affecting fruit trees in the region of Maputo, Mozambique. Materials and methods. Entomological surveys were carried out between June 2002 and December 2003 in the Districts of Manhiça, Marracuene, Namaacha and Matutuíne (southern Mozambique). Quadrangular 900-m2 plots were established in fields where Annona senegalensis, Garcinia livingstonei and Vangueria infausta native fruit trees naturally occurred. The number of individual insect pests per fruit, tree and plot was recorded to estimate ecological fauna measurements: the affinity index, association index and simultaneous constancy. Results and conclusion. A total of 1648 insect specimens, belonging to eight insect species, were found while conducting the ecological observations on Annona senegalensis Pers (Annonaceae), Garcinia livingstonei T. Anders (Clusiaceae) and Vangueria infausta Burch (Rubiaceae). Two groups of pests were observed: defoliators and insects attacking the fruits, which represented the majority. Affinity between insect species was observed, with the relationship between Ceratitis capitata Wiedemann and one unidentified species of the Cosmopterigidae family reaching the highest values. C. capitata was also found to have the highest association index with Spatulipalpia monstrosa Balinsky (Lepidoptera: Pyralidae), as well as Carpophilus sp. (Coleoptera: Nitidulidae) and Araecerus sp. (Coleoptera: Curculionidae). C. capitata and Araecerus sp. had the highest simultaneous occurrence in different locations. Cluster analysis also indicated that Ceratitis capitata and Carpophilus sp. had the highest similarity percentage in all samples.

Introduction. Prunus amygdalus and P. webbii can be used as rootstocks for almond cultivars due to their adaptability to severe environmental conditions. However, the time required for seedlings to reach a suitable size for transplanting may take 1 to 3 years. Our study tested the effects of foliar application of growth regulators on the vegetative growth and carbohydrate accumulation in shoots and roots of these species. Materials and methods. Six-week-old seedlings were treated with gibberellic acid (GA3) (100 mg·L–1) alone or with GA3 followed by ethephon [(100 and 200) mg·L–1], or chlormequat chloride (CCC) [(500 and 1000) mg·L–1], or paclobutrazol (PBZ) [(500 and 1000) mg·L–1]. Results and discussion. Most levels of plant growth regulators significantly enhanced seedling growth. However, GA3 alone was most effective on stem height, leaf area, and shoot fresh and dry weights of both almond species. The thickest stems of P. amygdalus and P. webbii were obtained from the application of 100 mg GA3·L–1 followed by application of (1000 and 500) mg PBZ·L–1, respectively. In both species, PBZ significantly increased leaf chlorophyll content compared with the controls as well as with the other treatments. Application of GA3 alone on P. webbii and of GA3 followed by 100 mg ethephon·L–1 on P. amygdalus showed the highest root number, and root fresh and dry weights. High levels of soluble sugars and starch in the shoots and roots of both species were observed when GA3 application was followed by PBZ. Conclusion. These results demonstrated that application of plant growth regulators to the seedlings might be a useful way of enhancing growth of P. amygdalus and P. webbii and reducing the time and cost of seedling production.

Introduction. This protocol makes it possible to determine the chromosome number of banana clones in root tip squashes. The principle, key advantages, starting plant material, time required and expected results are presented. Materials and methods. This part describes the required laboratory materials, and the four steps of the protocol used for the chromosome counts (root sampling and treatment, slide preparation, observation of useful cells and chromosome counts on useful cells). Possible troubleshooting is discussed. Results. The protocol usually results in condensed and intensely stained chromosomes.

Introduction. L’espèce Ricinodendron heudelotii, plante aux amandes oléagineuses en voie de domestication au Cameroun, est attaquée par un cortège d’insectes phytophages. Parmi ceux-ci, Diclidophlebia xuani Messi et al. (Hemiptera, Psyllidae) constitue son principal ravageur. Un inventaire de la faune d’arthropodes associée à cette plante a été effectué afin d’identifier les ennemis naturels de ce psylle. Matériel et méthodes. Des échantillons ont été collectés de 2001 à 2002 dans les environs de Yaoundé. Les organes végétatifs attaqués de R. heudelotii ont été récoltés chaque semaine et observés sous stéréomicroscope pour récupérer les arthropodes. Résultats et dicussion. Outre D. xuani, de nombreux autres phytophages ont été identifiés, les plus importants étant des lépidoptères. Des prédateurs et parasitoïdes du psylle et des autres arthropodes phytophages ont également été identifiés. Parmi les prédateurs du psylle, les plus importants sont les Anthocoridae, Coccinellidae, Miridae et Syrphidae ; les araignées jouent également un rôle indéniable dans la régulation des populations de D. xuani ; celles-ci n’ont toutefois pas pu être identifiées. Très peu de parasitoïdes ont été trouvés, essentiellement des Encyrtidae. Conclusion. Malgré la diversité de la faune auxiliaire recensée sur R. heudelotii au Cameroun, son impact sur les populations du psylle est apparu limité.