Introduction. A study on postharvest treatments of wild peppers was carried out in Madagascar with the aim of describing the local practices and measuring their impacts on the quality of the products. Materials and methods. Four distinct pepper production systems (PPS) were observed, described and compared in two separate areas in East Madagascar. Major quality characteristics (piperine and essential oil) of the peppercorns were assessed in samples collected in the four systems. Results and discussion. Two main postharvest processes (dry and wet) were identified. The wet process differed from the dry one in that it involved two specific operations, blanching and sweating. The processes influenced the color of the pepper. Piperine contents were not affected by any of the pepper production systems, whereas essential oil contents were reduced by up to 27% by the wet process. After processing, piperine contents were up to eight times lower, whereas essential oil contents were up to six times higher than the specifications of the standard ISO 959-1 for black pepper ready for commercialization. Conclusion. Two main processes (dry and wet) for treatment of peppercorns in Madagascar were identified and described. The dry process, with two steps less, appeared to be easier to implement and more respectful to the product. Improving maturity control and processing according to the quality expected by the markets will be necessary to promote Malagasy peppers.

Introduction. México is one of the most important producers and exporters of blackberries in the world. During postharvest handling, blackberry fruits are exposed to the attack of phytopathogenic fungi. Materials and methods. To obtain Rhizopus stolonifer isolates, samples of leaves and rhizospheric soils were placed on Petri plates containing Potato Dextrose Agar (PDA). In addition, fruits were also placed in humidity chambers at 25 °C. To describe the infection process on blackberry fruits by Rhizopus stolonifer, samples were taken at different intervals for a period of 72 h. All fungal isolates obtained were maintained on PDA. The bacterial colonies were isolated and purified by streaking on PDA. The antagonistic activity of the bacteria was assessed against R. stolonifer by dual culture technique on PDA. To detect the production of siderophores, the chrome azurol S assay was carried out. Results. The infection process of R. stolonifer on blackberry fruits was described for the first time in this work. Eighty-six bacterial isolates from different parts of the plant and rhizospheric soil were obtained. Bacterial isolates with antagonistic activity were identified and the production of siderophores was measured. Four isolates showed antagonistic activity against R. stolonifer. Bacillus subtilis obtained from soil was the most effective isolate. Conclusion. In this study we isolated and identified antagonistic bacteria with potential for biocontrol on Rhizopus stolonifer obtained from blackberry fruits. To our knowledge this is the first report regarding this topic.

Introduction. Black plum (Vitex doniana sweet) is a plant widely used by various communities in Nigeria for many purposes, including production of wine and jam. Ripe mature black plum fruit for food use commonly collected from the ground instead of plucked which is more hygienic. An investigation was conducted to find out the mycoflora on the surface and within the fruits of black plum fruits. Materials and methods. Mycoflora associated with the surface, skin, pulp and juice of healthy intact fruits of black plum was isolated in malt extract agar and potato dextrose agar and identified. Pathogenicity test was carried out with three pathogens of the fruit. Results and discussion. Fungi with incidence of 20-100% of occurrence were classified as major components and those below 20% of occurrence were regarded as minor components. Yeasts making up the major components in the ripe fruits were Saccharomyces cerevisiae and Candida albicans, while the minor yeast components were Rhodotrula sp., S. coreanus and Pichia sp. Filamentous fungi constituting major components were Aspergillus niger and Penicillium sp. whereas minor components were Botryodiplodia theobromae and Penicillium chrysogenum. Spoilage of fruits was caused by B. theobromae, Aspergillus sp. and A. niger. Conclusion. Yeasts and, occasionally, filamentous fungi occur within apparently healthy fruits of Vitex doniana sweet. Stages of development when the yeasts enter the pulp of the fruit need to be thoroughly investigated.

Introduction. This protocol describes a method for obtaining protoplasts from banana leaves, calli and cell suspensions, and their sustainable development via somatic embryogenesis from embryogenic cell suspensions. 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 media preparation for protoplast production and culture. Results. The first protoplasts may be seen after 30 min of incubation in enzyme maceration. With protoplasts from embryogenic cell suspension, complete development into a whole plant, through somatic embryogenesis, is observed in 12 weeks. The first cell divisions occur on feeder layers 3–8 days after protoplast plating. Proembryo formation is observed 14–21 days after initiation of protoplast culture. The transfer of derived embryo plantlets, at 8–10 weeks after protoplast plating, onto growth regulator-free medium, leads to plant rooting and elongation.

Introduction. Le manguier est l’un des arbres fruitiers les plus répandus en Afrique de l’Ouest. Un historique de son introduction dans la zone a été publié récemment. Pour faire suite à ce document, l’analyse présentée a été consacrée aux principales variétés qui y sont cultivées aujourd’hui et à l’impact des facteurs historiques et commerciaux sur la composition variétale des vergers. Quelques définitions. En préalable à un inventaire des variétés, certains termes permettant de les caractériser ont été précisés (précocité, monoembryonie et polyembryonie) et quelques informations sur l’origine des variétés floridiennes ont été fournies. Les principales variétés cultivées en Afrique de l’Ouest. Quatre catégories ont été distinguées : les variétés de mangues locales ou polyembryonnées (mangots, mangue du Cameroun), les premières variétés monoembryonnées propagées par greffage (Amélie, Julie, Sabot, Djibelor, Cuisse Madame), les variétés floridiennes, également monoembryonnées et propagées par greffage, introduites plus tardivement et utilisées soit pour l’exportation (Kent, Keitt, Palmer, Zill, Valencia, Smith, Irwin, Haden), soit pour les marchés régionaux (Brooks, Davis-Haden, Miami Late, Springfels, Beverly, Eldon, Ruby). Chaque variété a été décrite, de même ses caractéristiques culturales et ses débouchés. La composition des vergers de manguiers greffés. La composition des vergers greffés est influencée par l’évolution historique et la destination des fruits qui peuvent être autoconsommés, vendus sur le marché local, national ou sous-régional, exportés sur le marché international ou transformés dans des unités artisanales ou industrielles. Cette composition a été précisée pour la Guinée, le Mali, le Burkina-Faso, la Côte d’Ivoire, le Sénégal et le Togo.

Introduction. Calcium chloride (CaCl2) treatment has been shown to increase the shelf-life of fruits, mainly through making cell walls less accessible to pathogens and softening enzymes. Materials and methods. bananas of four cultivars [`Ambon' (AAA), `Embul' (AAB), `Kolikuttu' (AAB) and `Seenikehel' (ABB)] were dipped in or pressure infiltrated with 4% CaCl2. To determine the effect of exogenous ethylene on treated fruits, they were ripened with exogenous ethylene. Ca2+ in cell wall fractions were monitored by atomic absorption spectrophotometry. Cup plate assays were performed to determine pectinase activity. Results and discussion. Pressure infiltration accelerated ripening and disease, and reduced firmness (P < 0.05). However, when exposed to ethylene, CaCl2 pressure-infiltrated bananas were insignificantly firmer than distilled water-infiltrated and ethylene-ripened bananas, showing a significant interaction (P < 0.05) between infiltration treatments and ethylene ripening. There was no consistent increase in covalently bound pectin of cell walls as seen in fruits that respond positively to CaCl2. Firmness reduction and ripening acceleration by Ca2+ treatment cannot be explained if polygalacturonase (PG) (known to be inhibited by Ca2+) was the dominant pectinase. Enzyme assays gave evidence of PG activity. When ammonium oxalate (known to bind Ca2+) was eliminated from the test medium, pectinase activity increased with increasing pH (pH 5 to 9). The presence of a pectinase enzyme which exhibits activity in the presence of Ca2+ is apparent. Conclusion. Ca2+ does not appear to influence cell wall structure of bananas but appears to influence ripening physiology.

Introduction. The grapefruit tree has a long production period. In the Jordan Valley, harvest lasts from November to March. Many Jordanian farmers tend to harvest their fruit early to get high prices, regardless of its quality. Thus, the effect of the harvesting date on fruit quality of grapefruit cv. ‘Red Blush’ was evaluated under Jordan Valley conditions for two seasons, 2002 and 2003. Materials and methods. Fruit quality of uniform 25-year-old grapefruit cv. ‘Red Blush’ trees budded on sour orange rootstock was studied during the 2002 and 2003 seasons. Fruits were harvested from October 15 in both seasons with 15-day intervals with a total of eight harvests. The studied data were total soluble solids (TSS), titratable acidity (TA), the [TSS/TA] ratio and juice percentage. Results and discussion. Fruit total soluble solids and fruit juice percentages were at a minimal level during early harvesting dates and increased with time, reaching the maximum level on January 1 for TSS and January 15 for fruit juice percentage in the first season and on December 15 and February 1, respectively, in the second season, after that TSS decreased. Fruit titratable acidity values were at maximal levels during early harvesting dates (October 15) and decreased with time, reaching the minimum level on February 1 in the first season and on January 15 in the second season. The [TSS/TA] ratio ranged from 5.5 to 6.0 between January 1 and February 1 in the first season, and between December 1 and January 15 in the second season. Conclusion. Our study displayed that Jordan Valley growers are harvesting their grapefruits much too early to provide acceptable eating quality fruits to local markets.

Introduction. The date palm tree is one of the fruit trees most cultivated in the Arabian Gulf States. Bioregulators were used for the quality and productivity improvement of date palm tree fruits. A study was conducted to assess the relative effectiveness of GA3, NAA, ethephon and a mixture of growth regulators on some fruit characteristics and productivity of the Barhee date palm tree cultivar. Materials and methods. Five selected female uniform date palm trees of the cultivar Barhee were pollinated on March 5-15, 1994, 1995 and 1996, by placing eight fresh male strands on the female spadix center (flower cluster).Ten flower clusters were used on each tree and divided into five groups of two flower clusters. Each of these groups was subjected to one of the following treatments: control (water), 150 mg GA3 × L-1, 100 mg NAA × L-1, 1 000 mg ethephon × L-1 and a mixture of these three growth regulators. Then the fruit setting, fruit flesh and dry matter percentages, the total soluble solids, the fruit ripening, and the fruit weight per bunch and per tree were measured. Results and discussion. The data showed that the application of GA3 or ethephon on flower clusters of Barhee date palm trees had no constant effect on fruit characteristics and productivity of trees. NAA or growth regulator mixture applications on Barhee flower clusters reduced the fruit dry matter and fruit ripening percentages and increased the fruit weight per bunch and per tree. Conclusion. Treatments of Barhee date palm flower clusters, 20 d after pollination, with NAA or the specific growth regulator mixture decreased the dry matter percentage and the fruit ripening and increased the fruit flesh percentage and the date palm tree yield, therefore, these treatments could be recommended to improve the productivity of date palm trees in the region.

Introduction. The chataigne or breadnut, Artocarpus camansi Blanco, has high nutritive value but it is an under-utilised food source. Yield losses due to tree height and limited information on productivity are constraints to commercial production. Our study was undertaken to determine fruit yield and seed yield, the relationship between fruit size and seed yield, and the response of yield to pruning. Materials and methods. Fruit and seed yield data were collected from 1996 to 2002 from three seedling trees established at the University of the West Indies in Trinidad and Tobago in 1993. The trees were pruned in December 1998. Results. The highest fruit mass per tree (139.7 kg), fruit number per tree (126) and seed mass per tree (59 kg) were obtained in 5-year-old trees. Fruit and seed yields were significantly (P < 0.001) lower in the years after pruning. Fruit mass per tree was positively correlated with fruit number (r = 0.99). Seed mass per fruit was positively correlated with seed number per fruit (r = 0.87) and both variables had strong, positive correlations with mean fruit mass (r = 0.83 and r = 0.77, respectively) and fruit volume (r = 0.63 and r = 0.67, respectively). Discussion and conclusions. Chataigne fruit and seed yield potential is greater than originally estimated. Both are strongly related and selection for high seed number per fruit with more effective pollination, disease control and proper tree height management may further increase productivity. In the field, estimated fruit volume is the most practical indicator of seed yield.

Introduction. The objectiveof this study was to examine the relationships among the ripeningattributes of ‘Honeycrisp’ apples at harvest and after storage,and the direct and indirect contributions of these attributes topeel greasiness and the incidence of soft scald and soggy breakdownduring storage using correlation and path-coefficient analyses. Materialsand methods. Fruit were harvested from a commercial orchardat least five times throughout the commercial harvest period during foursubsequent years (2008 to 2011). In two of the years, fruit werestored in air for 3 months at 3 °C and/or in a controlled atmosphere(1–2 kPa O2 + 1–2 kPa CO2) for 6 months at 3 °C. Fruit were analyzedat harvest and after storage. Results and discussion.Negative correlations were detected between internal ethylene concentration(IEC) and soluble solids concentration (SSC) or titratable acidity(TA) (the higher the IEC, the lower the SSC and TA) and a positivecorrelation between firmness and TA (the higher the firmness, thehigher the TA). More peel greasiness and higher incidence of soggybreakdown during storage were associated with lower firmness, SSCand TA. Negative correlations were also detected between the incidence ofsoft scald and IEC or peel greasiness. The results of the path-coefficientanalyses suggest that, in ‘Honeycrisp’, interrelationships amongpostharvest ripening indices and each individual disorder differ. Threepossible path models for the interrelationships among ripening attributes (independent variables)and the incidence of peel greasiness, soft scald and soggy breakdown(dependent variables) are presented.

Introduction. The present study had as objectives to measure the palm leaf divergence angle in the field, to determine the frequency of trees and offshoots showing clockwise and counterclockwise phyllotaxis, to establish the relationship between phyllotaxis of the mother tree and that of its offshoots, and, finally, to determine the effect of the divergence angle value on production. Materials and methods. The vegetal material was composed of four Moroccan cultivars of Phœnix dactylifera L. Observations were conducted in the south of Morocco on 20 trees per cultivar and four offshoots per tree. The divergence angle was measured on adult trees whereas phyllotaxic direction (clockwise or counterclockwise) was noted for both offshoots and adult trees. Results and discussion. This study showed that the phyllotaxic direction of the offshoots presents a clockwise or counterclockwise phyllotaxis independently of the mother plant. The divergence angle varied depending on the cultivar. This character is an interesting criterion, both for the selection of the best adapted cultivars for the marginal date palm growing regions, and for an optimal production.

Introduction. The fruit and vegetable sector group of the French National Institute for Agricultural Research (INRA) undertook a bibliometric analysis of INRA scientific academic literature on fruits and vegetables for the 2000–2006 period. This study made it possible to produce quantitative and qualitative indicators that will shed light on the institute's scientific position in relation to the fruit and vegetable sectors. Materials and methods. Different steps were taken to constitute and process a corpus of INRA researcher publication data. The citation corpus gathering bibliographic data was constituted using the Web of Science. The Sphinx data processing program allowed the constituted databases to be structured and manipulated. Results. After the data were cleaned, there was a total of 1463 articles published by INRA authors between 2000 and 2006; this constituted the “fruit and vegetable corpus” studied, which represented 8% of the total number of INRA publications during this period. The typology of fruits and vegetables studied at INRA, the INRA research centres involved, the main subjects addressed by INRA research divisions and the national and international partnerships of INRA authors were analysed. Conclusion. The analysis presented highlights the overall magnitude of research dedicated to fruits and vegetables at INRA. This research is undertaken in the principal research centres of horticulture and/or fruit regions, with a high level of involvement of Southeast centres of France. Partnerships with other French and foreign organisations are numerous. This assessment allows an understanding of the rapid evolution of research that has occurred over the past several years in the fruit and vegetable field, notably the growing involvement of nutrition and consumer sciences. The development of multi-disciplinary and integrated approaches must also be emphasised.

Introduction. Litter on the ground is a primary source of Botrytis cinerea inoculum in boysenberry (Rubus hybrid) gardens. The effect of litter management on primary inoculum production, and flower and berry infections was determined. Materials and methods. A series of experiments ranging from laboratory to large-scale field evaluations were conducted in New Zealand during 1997-2002 to evaluate litter management options for control of B. cinerea. The laboratory trial investigated the effect of litter size (shredded vs. unshredded litter) and debris amendments on tissue degradation and B. cinerea colonization. The field trial (four sites) investigated the effect of litter amendments (compost, urea and fungicide) and piling litter on B. cinerea sporulation. In the 4-year commercial-scale study (three properties), the effect of litter treatment (piling, compost and microbial extracts/suspensions) on primary inoculum, flower and berry infections was assessed. Results and discussion. The laboratory trial showed that bark + sewage sludge compost amendment enhanced litter decomposition and reduced B. cinerea sporulation on infected tissue after 8 weeks. The field trial indicated that piling of shredded boysenberry debris was more important than litter amendments in reducing the amount of B. cinerea harbored within the litter. Commercial field-scale evaluation of litter management options verified that piling of shredded litter is the most important step in B. cinerea inoculum control from debris. It also showed that microbial litter amendments (compost, solutions or extracts) can be beneficial. While B. cinerea inoculum control also reduced the amount of flower infections, berry infections at harvest were not affected, indicating that other sources of B. cinerea inoculum contribute to berry infection post-flowering.

Introduction. Root-knot nematodes (Meloidogyne sp.) cause significant economic damage to Prunus species in China. One of the most economical and environmentally sustainable methods to reduce the impact of root-knot nematodes is the use of resistant rootstock cultivars. Our aim was to examine resistance to M. incognita and its mechanisms. Materials and methods. Four rootstocks were assessed: Tsukuba-4 (P. persica), Tsukuba-5 (P. persica), Nanking cherry (P. tomentosa) and wild peach (P. persica). The susceptible tomato (Lycopersicon esculentum Mill.) cultivar ‘Baiguoqiangfeng’ was used as a positive control. Results. Nematodes did not penetrate roots of Tsukuba-4 and Tsukuba-5, which were considered to be immune varieties. Nanking cherry was highly resistant to M. incognita, whereas wild peach was susceptible. Conclusion. The differences in resistance among the rootstocks were not attributed to differences in effects of root diffusates, but were related to the different structural organizations of the root tips. The epidermal structure of Tsukuba-4 and Tsukuba-5 completely prevented the penetration of second-stage juveniles of M. incognita (J2). In Nanking cherry, penetration of J2 juveniles was reduced, and the development of nematodes from the J2 to female stage was delayed.

Introduction. La culture des agrumes est très répandue en Guinée sous forme de vergers decase. La moyenne Guinée (Fouta Djalon), principale région productrice d'oranges, assure environ les deuxtiers de la production nationale et la presque totalité des exportations régionales. Cependant, à la finde 1993, la cercosporiose due à Phaeoramularia angolensis a envahi les zones d'altitude du pays àpartir de foyers primaires situés en moyenne Guinée, entraînant une nette diminution de la production.Matériel et méthodes. Trois enquêtes par région naturelle et par an ont été effectuées dans plusieurs localités du pays pour établir les limites d'extension de la maladie. Des échantillons defeuilles et de fruits suspects, prélevés sur 25 arbres par localité, ont été identifiés en laboratoire. Lavitesse moyenne de progression de la maladie a été estimée. Résultats et discussion. Les observationsfaites en champ et complétées par les travaux de laboratoire entre 1995 et 1998 ont confirmé la présencede la maladie. Les zones agrumicoles situées à plus de 400 m d'altitude ont été particulièrement touchéespar le fléau. Les zones basses et chaudes de la Guinée maritime et de la haute Guinée sont épargnées. Lamaladie progresserait à une vitesse de 23 km $\cdot$ an-1. Conclusion. La cercosporiose desagrumes continue sa progression en Guinée. La presque totalité des vergers du Fouta Djalon est atteinte.La reconversion des zones agrumicoles touchées par la maladie devrait être envisagée par diversificationfruitière et délocalisation des nouvelles plantations vers des zones basses et écologiquement protégées.

Introduction. En Tunisie, bien que des problèmes liés à la floraison et à la fructification se posent chez le grenadier (Punica granatum L.), aucune étude n'avait encore été menée sur cette espèce. Nos travaux ont donc cherché à étudier ces importantes étapes du cycle de reproduction de la plante chez certaines variétés locales de P. granatum exploitées dans les conditions tunisiennes. Matériel et méthodes. La dynamique de la floraison a été étudiée par le comptage régulier des fleurs formées sur branches des trois cultivars locaux : Gabsi, Kalaii et Garoussi. La chute des boutons floraux, des fleurs épanouies ou des jeunes fruits récemment noués a été comptabilisée pour l'arbre entier. Un suivi de la fertilité des fleurs et des essais d'autopollinisation par ensachage de rameaux de différentes longueurs ont été conduits sur le seul cultivar Gabsi. Résultats et discussion. La durée de la floraison a été de 8 semaines environ pour Gabsi et de 10 semaines pour Garoussi et Kalaii. Le maximum des fleurs a été obtenu entre la troisième et la cinquième semaine après le début de floraison. La majeure partie des fleurs est apparue sur du bois âgé d'un an ou plus. Le taux de rétention le plus élevé (8,4 %) a été enregistré chez le cultivar Gabsi. Les fruits ont surtout été obtenus à partir des fleurs hermaphrodites. Le calibre des fruits à la récolte a diminué au fur et à mesure que la date d'apparition des fleurs dont ils provenaient avait été tardive. Les rameaux courts ensachés n'ont pas retenu de fruits ; ceux de longueur moyenne ont permis un taux de nouaison de 2,3 % par rapport à la totalité des fleurs du rameau ; les rameaux de plus grande taille ont présenté un taux de 4,8 %. Conclusions. La floraison du grenadier est très échelonnée. Les cultivars étudiés ont différé en fonction de la date du début de floraison, de sa durée et de son intensité. Le régime de reproduction s'est révélé être l'allogamie préférentielle. L'étalement de la floraison et les particularités morpho-physiologiques des fleurs favoriseraient plutôt la pollinisation croisée.

Introduction. This protocol can be used as a guide for people who wish to construct their own nursery. It describes the methods for receiving, transplanting, managing and hardening young banana tissue culture plants after the weaning stage. The principle, key advantages, starting plant material and time required are presented. Materials and methods. This part describes the nursery construction, the nursery media, fertiliser and bags, the handling and transplanting of weaned plants into bags (3 steps), and the management schedule for hardening nursery plants (8 steps). Possible troubleshooting is listed. Results. All the characteristics of nursery-hardened plants in bags, ready for transplanting to the field, are formulated.

Abstract – Introduction. The susceptibility of banana fruit to crown rot andanthracnose, the two main banana post-harvest diseases, is influenced by many pre-harvestabiotic factors. Mycosphaerella leaf spot diseases (MLSD) of bananas arebiotic pre-harvest factors, which have an influence on fruit physiology. The fruit’ssusceptibility to post-harvest diseases may also be influenced by foliar diseases causedby M. fijiensis, responsible for black leaf streak disease (BLSD), andM. musicola, which causes sigatoka disease (SD). The aim of our studywas to determine the influence of these biotic pre-harvest factors on banana fruit’ssusceptibility to crown rot and anthracnose. Materials and methods. A diseaseseverity gradient was established in two experimental fields (Cameroon for BLSD andGuadeloupe for SD) where, at the flowering stage, six different levels of MLSD severitywere selected. Fruit susceptibility was determined through necrotic surface assessmentsafter artificial inoculation by Colletotrichum musae on the 3rd hand ofharvested bunches. Results and discussion. BLSD significantly influencedbanana sensitivity to crown rot (P < 0.001) but only had a slighteffect on the development of anthracnose ( P = 0.041). SD had no effect(P > 0.05) on banana susceptibility to either post-harvest disease.These results are discussed with emphasis on the influence of variations in thesource-sink ratio on fruit physiology. The influence of BLSD on crown rot disease suggeststhe need to take into account the management of these foliar diseases for an alternativecontrol method of post-harvest diseases through integrated pest management programs.

Introduction. Algerian oasesare characterized by a diversification of local fruit species andcultivars. However, this diversity is subject to erosion. To preservethe genetic heritage, we undertook the first work on the inventoryof fruit species crops in the region of Touggourt in south-easternAlgeria. Materials and methods. Our working methodswere based on surveys carried out on farms in the Oued Righ regionaccording to a questionnaire that met our objectives. For this,we divided the study region into three zones and in each zone weselected ten farms for the inventory of fruit species cultivated. Results and discussion. The results of our investigationsallowed us to identify thirteen species, including four specieswith a wide distribution (pomegranate tree, apricot tree, fig treeand vine). The local genetic diversity of these species is littleknown. The varieties or cultivars inventoried have local names givenby the farmers in the region according to certain morphologicalcharacteristics of the fruit. We surveyed five cultivars for thefig tree, two cultivars for the pomegranate tree, two cultivarsfor the vine, and two apricot tree cultivars. The study of the biodiversityof fruit trees in the Oued Righ region showed high richness of thespecies and cultivars; some are local and others are endemic tothe region. Better knowledge of genetic diversity will begin withtests of behavior and characterization of the different genotypes encounteredto dispel the ambiguities and to highlight the actual compositionof populations or varieties of different species.

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.