Introduction. Generally, in Iran, citrus cultivars are grafted on Sour orange rootstocks. However, susceptibility of this rootstock to tristeza (CTV) has required a research program to replace Sour orange trees with other rootstocks. Materials and methods. Yield performance and fruit quality of Ruby Red and Marsh grapefruits were assessed for 5 years (1999 to 2003) in the Agricultural Research Station in Dezful (Southern Iran) according to the eight different rootstocks used: Carrizo citrange, Citrus amblycarpa, Cleopatra mandarin, King mandarin, Sour orange, Swingle citrumelo, Troyer citrange and Volkamer lemon. Results and discussion. For the 5 years studied, cumulative yields per tree and yield per trunk cross-section area were the highest on Cleopatra mandarin, Sour orange, Swingle citrumelo and Volkamer lemon, whereas trees on Citrus amblycarpa, Carrizo citrange, King mandarin and Troyer citrange were the least productive. The results showed that individual fruit weight, size and skin thickness were significantly higher for both cultivars on Volkamer lemon, compared with the other rootstocks. Fruits on the Cleopatra mandarin rootstock had the lowest weight and fruit diameter. The rootstock type also affected the fruit juice amount and soluble solid content. Fruits from cultivars which were grafted on Sour orange rootstock had total soluble solids of 9.93% and 51% of juice content, whereas on Volkamer lemon rootstock, they had 7.81% of total soluble solids and 45.3% of juice content. Total acid of the fruits from cultivars grafted on Volkamer lemon had the significantly smallest amount (1.33%). In both cultivars of grapefruits, no significant differences were observed except in the size of the fruit, fruit juice and vitamin C contents. Interactions between rootstock and cultivar were significantly different. Conclusion. Our results indicated that the yield and fruit quality of grapefruit are strongly influenced by the rootstock used. Also, the interaction between cultivars and rootstocks may be an interesting strategy for the adaptation of cultivars to different climatic areas.

Introduction. Root restriction occurs when seedlings are grown in increasingly small containers and it reduces plant growth in different ways. Therefore, the objectives of our study were to investigate the effects of varying container sizes and irrigation frequency on growth parameters of ‘Rough lemon’ (C. limon) plants Maseno, Kenya. Materials and methods. The treatments tested the effect of three container volumes (1.7 L, 2.7 L and 4.5 L) and three irrigation frequencies [every day (W1), every two days (W2) and every 3 days (W3)]. The design of the experiment was completely randomized with three replications. Growth parameters studied were plant height, canopy height, shoot and root weight, number of leaves and shoot to root ratio. Results and discussion. Increasing container volumes generally increased the height of plants, height of canopy, weight of whole plants and weight of roots, but it did not affect number of leaves, stem diameter or shoot to root ratio. Irrigation frequency increased number of leaves, height of plants, height of canopy, stem diameter and weight of shoots and roots, but this factor had no effect on weight of whole plants. These findings are explained by reduced root restriction in the largest container volumes. Conclusion. Increasing container volumes from 1.7 L to 4.5 L and irrigation frequency from every 3 days to every day increases plant growth as expressed in the various plant growth parameters.

Introduction. Dried mango slices are a common snack product in Southeast Asian countries. Mashing the carotenoid-containing mango flesh and drying the puree to mango leather is a promising alternative to utilise even over-mature or small fruits and fruits with irregular size as low-cost raw materials. Within the study, the impact of blanching and air temperature (40–90 °C) on drying time and quality was investigated. Materials and methods. Drying tests were conducted using a laboratory dryer, which allowed continuous measurement of the drying rate. The quality of the mango leather was evaluated in terms of colour (CIE-Lab) and β-carotene content (HPLC). The formation of 13-cis-β-carotene isomer was used to indicate thermal β-carotene degradation. Results and discussion. Blanching degraded the β-carotene content, reduced drying time (–20%) and decreased browning reactions. Optimum drying conditions in terms of drying time, colour and β-carotene retention were determined at 80 °C. The all-trans-β-carotene content was maintained at 75% and no decrease in colour saturation (C*) was observed. As a result, it is expected that 80 °C is sufficient to inactivate carotenoid oxidising enzymes without showing significant negative thermal effects on β-carotene degradation. Higher temperatures led to severe β-carotene losses. Lower temperatures increased drying times, caused discolouration and decreased the β-carotene retention. Conclusion. With a provitamin A activity of (600 to 650) retinol equivalents (RE), mango leather is a promising source of provitamin.

Introduction. Dacryodes edulis and Canarium schweinfurthii are two tropical multi-purpose trees in Cameroon which produce fruits (African pear and Black olive, respectively) for human consumption, which are marketed more and more on the national and international markets. This study aimed at characterising these two fruits starting from their physical and chemical properties. Materials and methods. Fruits were collected during the harvest peak in three agro-ecological zones of Cameroon. The physical properties measured were the weight, the length, the fruit circumference and the pulp thickness, while the chemical analyses included the moisture and protein, lipid and ash contents. Results. The fruits from the humid forest were largest (96 g), whereas the smallest came from the grassland (54 g). The highest pulp per fruit content (69% for the African pear and 57% for Black olive) was observed in fruits harvested in the humid forest zone. The strongest correlation (r = 0.25) between the fruit weight and that of pulp was observed for Black olive produced in the humid forest zone. The crude protein rate was highest (8%) in fruits from the humid forest, whereas that of the lipids (42%) prevailed in the semi-forest zone. Conclusion. The humid forest zone offers the best agro-ecological conditions for commercial production of the fruits of D. edulis and C schweinfurthii. These two fruits contain proteins and lipids in significant quantities and can, consequently, be used as alternative sources for these nutritive elements.

Introduction. En Tunisie, les dattes de type Deglet Nour sont réputées pour leur couleur jaune doré et elles présentent une valeur marchande élevée ; elles constituent la majorité des dattes exportées vers l’Europe. L’objectif de nos travaux a été d’étudier l’effet de l’oxygène et de la température sur la dégradation de la couleur de ce type de dattes durant la période d’entreposage. Matériel et méthodes. L’évolution de la couleur de dattes du type Deglet Nour stockées sous humidité relative constante (75 %), à trois températures différentes [(10, 25 et 37) °C] et en présence de trois concentrations d’oxygène [(0, 20 et 40) %] a été suivie chaque semaine durant 35 jours à l’aide de la mesure des paramètres L* et b* de l’échelle Hunter Lab. Résultats. La température a joué un rôle déterminant dans la dégradation de la couleur des dattes durant l’entreposage et l’effet de l’oxygène a été important quoique secondaire. Conclusion. La couleur des dattes au cours de leur stockage se révèle pouvoir être prédite à partir du seul paramètre b* de l’échelle Hunter Lab. Dans le cas des dattes conditionnées sous différentes concentrations en oxygène et à différentes températures, la perte de la couleur initiale du fruit a été davantage expliquée par une augmentation de la température ambiante que par la variation de la concentration en oxygène du milieu de conservation. La dégradation de la couleur serait causée par des brunissements non enzymatiques et enzymatiques oxydatifs.

Introduction. Mature-green Golden apples (Spondias cytherea Sonnerat) are used in the French West Indies for the preparation of a nectar. With the aim of improving the fruit processing conditions for a better quality of this beverage, morphological and compositional characteristics of the mature-green fruits were determined. Materials and methods. Mature-green fruits were harvested in Martinique (French West Indies) and characterised: diameter, length, mass, and colour were determined; pH, titratable acidity, soluble solids, sugars, proteins, starch, fibre, vitamin C, phenols and green pigments were measured. Results and discussion. Average fruit length, diameter and weight were 71 mm, 54 mm and 116.4 g, respectively. With a low pH (2.6) and a high titratable acidity (1.3 g citric acid Eq·100 g–1 fresh material), mature-green Golden apple is an acidic fruit comparable to the lemon. The fruit is rich in vitamin C (52.0 mg·100 g–1), phenols (349.5 mg gallic acid Eq·100 g–1) and starch (7.1 g·100 g–1). The pale green colour of the pulp is due to pheophytins a and b. Conclusion. Our study provided a detailed analysis of mature-green Golden apples, which will be taken into account for the improvement of nectar processing conditions.

Introduction. Planting time is considered as one of the most important factors for successful strawberry cultivation. Traditionally, under north-Indian plains, strawberry is planted after the second week of October, which results in the availability of fruits for a month or so. With the use of plasticulture techniques, the planting time can be enhanced, which facilitates early and higher production, and enhances availability of the fruit for a longer period. Mulching is the most important cultural practice in strawberry, which influences plant growth, fruit yield and quality. Hence, studies were conducted to determine the influence of planting time and mulching on growth, flowering and fruiting behaviour, yield and quality of strawberry in northern plains of India. Materials and methods. Studies were conducted on ‘Chandler’ strawberry with three planting times (mid-September, mid-October and mid-November) as the main effect and three mulching materials (black polyethylene, clear polyethylene and paddy straw) as the sub-main effect in a split-plot design with three replications. Standard procedures were adopted for making observations on plant growth parameters, flowering and fruiting behaviour, yield and quality parameters under different treatment combinations. Results and discussion. Mid-September planting favoured vigorous growth, enhanced flowering and fruiting, which resulted in the production of the largest fruits and highest yield of the best quality. Among the three different mulch materials, plants mulched with black polyethylene had the best growth, fruit weight, yield and quality compared with those mulched with clear polyethylene or paddy straw mulch. The [planting time × mulching] interaction was also found to be significant for all measured parameters. Conclusion. Our study revealed that, in northern plains of India, to get an early and high yield of the best quality under a micro-irrigation system, Chandler strawberry could be planted in mid-September if mulched with black polyethylene.

Introduction. L’identification des composés d’arôme des dattes permet d’apprécier leur qualité organoleptique ; elle revêt en outre un intérêt technologique en guidant les industriels dans certains processus de transformation du fruit et de production d’extraits d’arômes à partir des variétés de faible qualité, augmentant ainsi leur valeur marchande. Notre étude a eu pour objectif d’identifier des composés volatils responsables de l'arôme de huit variétés de dattes marocaines. Une classification statistique des variétés étudiées, basée sur leurs profils aromatiques, et une comparaison avec les résultats de travaux antérieurs effectués sur les composés d’arôme des dattes ont été également réalisées. Matériel et méthodes. Les composés volatils ont été analysés par la technique de piégeage dynamique de l’espace de tête et par désorption au micro-onde, puis ils ont été conjointement identifiés par chromatographie en phase gazeuse-spectrométrie de masse. L’étude statistique des données a été réalisée par analyse factorielle des correspondances et par classification hiérarchique ascendante. Résultats et discussion. Quarante-sept composés ont été identifiés dont vingt-trois non identifiés auparavant dans la datte. Cinq composés : la 2,3-pentanedione, le 2-méthyl-butanal, l’hexanal, le n-pentanol et le limonène se sont révélés être communs à toutes les variétés, tandis que certains composés ont été caractéristiques d’une variété particulière. La variété ‘Aziza’ s’est distinguée par la présence de cyclobutanol, de p-cymène et de 1,3-diméthyl-benzène. Le cyclopentadécadièn-1-one, l’éthanol et le géraniol ont été identifiés respectivement dans les variétés ‘Najda’, ‘Mejhoul’ et ‘Boufeggous’. En revanche, les variétés ‘Bouskri’ et ‘Iklane’ ont présenté une grande similarité de leurs profils aromatiques. Conclusion. Des différences de profils aromatiques entre les huit variétés étudiées ont été mises en évidence et des composés volatils « spécifiques » ont pu être identifiés.

Introduction. The isolation of humic acid (Ha) from decomposed organic substances such as compost is time-consuming, as it takes not less than 24 h. We investigated whether the isolation time of Ha produced from composted pineapple leaves could be reduced. Materials and methods. Ha from 10 g of pineapple compost was extracted with 100 mL of 0.10 M NaOH. Different extraction times [(4, 8, 12, 16, 20 and 24) h] were tested. At the end of each time, the samples were centrifuged. The dark-colored supernatant liquor containing Ha was decanted and filtered; the pH of the solution was adjusted to 1.0. After acidification, the fractionation times tested were (3, 6, 9, 12, 15, 18, 21 and 24) h. At the end of each fractionation time, the supernatant liquor (fulvic acid) was siphoned off from the acidified extract. The remainder of the suspension was transferred to a polyethylene bottle. Ha was purified by suspending it in 50 mL distilled water, then centrifuged, and the supernatant was decanted. After repeating this procedure five times, the supernatant and the fulvic acid were analyzed for Ca, K, Mg, Mn, Na, Cu, Fe and Zn. The washed Ha was oven dried at 30 °C to a constant weight and the Ha samples were analyzed for ash and mineral matter. Results and discussion. The ash content was not more than 1%, the generally acceptable maximum value. The mineral contents decreased in Ha samples with washing. The yield of Ha significantly increased with increasing extraction time, except for the (20 and 24) h extraction times, which did not show statistically different Ha yield, meaning that the exchange sites of Ha of the pineapple compost might have been saturated with Na ions from 20 h. There was no significant difference among the fractionation times, indicating that Ha of the pineapple compost requires about 3 h to equilibrate or stand immediately after acidification for the H ions to replace the Na and the other cations. There was no significant interaction between the factors extraction and fractionation. Conclusion. The isolation of humic acids from composted pineapple leaves can be achieved with an extraction time of 20 h and a fractionation time of 3 h.

Introduction. La propagation in vitro d’A. glabra L. non encore étudiée pourrait permettre de remédier à certaines difficultés de multiplication de cette espèce fruitière ligneuse. Des techniques de micropropagation ayant été déjà expérimentées avec succès avec d’autres espèces d’Annona (A. squamosa, A. cherimola, A. muricata), nous avons cherché à développer un système complet de micropropagation d’A. glabra L. en utilisant des explants de jeunes plantules. Matériel et méthodes. Pour la phase de prolifération de bourgeons axillaires (durée 30 jours), des boutures de segments nodaux prélevées sur la tige de jeunes plantes matrices ont été mises en culture dans un milieu de base MS supplémenté en différentes concentrations de BAP, utilisée seule ou en combinaison avec différentes concentrations d’ANA, et avec ou sans 1,0 mg de GA3·L–1. À l’issue de cette phase, le nombre moyen de tigelles obtenues par explant et leur taille moyenne ont été mesurés pour chacun des traitements. Pour l’enracinement des tigelles obtenues à l’issue de cette prolifération, diverses concentrations d’AIB et différents pH du milieu ont été testés (durée 15 jours). À la fin de cette phase, le nombre moyen de racines obtenues par tigelle et leur taille moyenne ont été évalués. L’acclimatation des microplants a ensuite été suivie en conditions contrôlées pendant 21 jours. Résultats et discussion. Tous les traitements, même ceux dépourvus de régulateurs de croissance, ont permis d’obtenir en moyenne 1,5 tigelles par segment nodal. Toutefois, les tigelles les plus développées ont été obtenues en utilisant 0,5 mg·L–1 de BAP utilisé seul. L’addition de 1,0 mg de GA3·L–1 au milieu de multiplication n’a pas été favorable au développement des tigelles. Durant l’expérimentation in vitro, une nécrose de l’extrémité des tigelles et une abscission foliaire ont pu être observées ; cela pourrait être lié à un déficit en calcium et à l’accumulation d’éthylène à l’intérieur du récipient de culture. Le pourcentage le plus élevé de boutures enracinées et le plus grand nombre de racines produites par explant ont été obtenus sans addition d’AIB au milieu de culture, en utilisant 4,0 mg·L–1 de charbon actif et un pH de 5,0. Les microplants avec racines ont été acclimatés avec succès.

Introduction. Although some of the non-formal food items consumed in Southeastern Nigeria are exotic, the indigenous products are becoming increasingly popular. There is also a growing interest among scientists in various disciplines to conduct research on nutritional, medicinal, industrial and other uses of the less studied and largely indigenous plants. Unlike the exotic fruits and seeds literature on the purely indigenous species is scanty. This paper is aimed at the documentation of some of the readily identified species producing fruits and seeds, which are considered to be endangered. Materials and methods. Selected plants producing edible fruits and seeds and considered to be endangered in Southeastern Nigeria were compiled in a list. Mature forms of the fruits and seeds were covered by means of color photographs and further categorized according to their families, growth habits, state of domestication, local names and methods of utilization. Results and discussion. Thirty plant species belonging to 19 families were recorded. The list includes 19 trees, 3 shrubs, 4 climbers and 2 rhizomatous monocots. About 27% of the species listed enjoy some degree of cultivation, while about 70% may still be found protected or wild. Up to 16% are still harvested only from the wild plants. The factors predisposing most of the species to extinction would be: loss of habitat due to deforestation and other forms of population pressure on the ecosystem; lack of interest in tree planting due to rather long gestation periods of existing genetic stock; increasing pressure and demand from few surviving stands; unsustainable harvesting methods. Conclusion. Ex situ conservation strategies, genetic and other tree improvement studies, encouragement of home garden and village forest settlement practices, and the introduction of incentives for tree planting are recommended strategies for conservation and sustainable production of the highly prized indigenous edible fruit and seeds in the area.

Introduction. The introduction of the elite variety of black mulberry under saline conditions could have a significant long-term impact on development in the impoverished rural areas. Materials and methods. Plants of the Pakistan mulberry cultivar were propagated by budding on Japanese mulberry seedlings. Trees were cultivated under saline soil conditions in Egypt. Results and discussion. Trees successfully bloomed and produced fruits after 2 years of budding. Intensive flowering and fruiting occurred in the third seasons. Four to six catkins developed on each branch or spur. Each catkin consisted of an average of 315 flowerlets, stacked on a peduncle. Fruits were found to be parthenocarpic. During ripening, fruits changed from the green stage to the ruby-red stage, then to the dark-purple stage. Fruit ripening began in the second week of March and extended to the third week of April. Ripe fruit ranged from (7.3 to 11.8) cm in length and from (1.3 to 1.5) cm in diameter. Fruit weight ranged from (8.3 to 10.2) g. TSS of the fruit juice ranged from (13.0 to 17.5) °Brix, while pH ranged from 3.1 to 3.36. Fruits contained 10.2% carbohydrates, 1.4% protein and 1.2% fibers. Fruits were found to be a good source of iron, potassium, calcium and phosphorus. Fruits contained a medium level of vitamin C. Average crop production per tree in the second and third seasons was (51 and 96) kg, respectively. Ripe fruits could not survive more than 5 days’ storage at room temperature, but survived 3 weeks of cold storage.

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.

Introduction. Ricinodendron heudelotii Baill. est une essence forestière en voie de domestication au Cameroun où la plante est appréciée pour ses vertus alimentaires, écologiques et médicinales. Les dégâts causés par le psylle Diclidophlebia xuani Messi et al. aux jeunes plants, en pépinière ou après leur plantation, constituent l’une des principales contraintes à la domestication de l’espèce. La biologie de ce ravageur a donc été étudiée afin d’envisager son contrôle. Matériel et méthodes. Différents aspects de la biologie de D. xuani ont été abordés : processus d’accouplement, choix du site de ponte par la femelle, maturation sexuelle des imagos, fécondité des femelles, longévité des imagos, développement embryonnaire et larvaire, sex-ratio à l’émergence et spécificité alimentaire. Les expérimentations ont eu lieu dans la région de Yaoundé soit en champ, soit en milieu contrôlé durant les années 2001 et 2002. Résultats et discussion. Les mâles de D. xuani ont émergé avant les femelles et le rapprochement des sexes a eu lieu 15 min environ après la mue imaginale. La longévité des femelles a été de 29 jours en moyenne, celle des mâles, de 7 jours. La ponte a commencé 3 jours après l’émergence et s’est poursuivie jusqu’à la fin de la vie de la femelle. En période chaude (28 °C environ), une femelle a pondu en moyenne 532 œufs pendant toute sa vie ; en période de basses températures (24 °C à 26 °C environ), la fécondité moyenne a été de 758 œufs. Les œufs sont essentiellement déposés sur les étages foliaires les plus jeunes de R. heudelotii. Les développements embryonnaire et larvaire ont duré respectivement 7 jours et 22 jours environ. Le cycle de développement, d’œuf à œuf, a nécessité 32 jours en moyenne. Le sex-ratio a été proche de 1. Conclusion. D. xuani se développe entièrement et sans interruption sur R. heudelotii ; il n’a jamais été rencontré sur d’autres espèces de plantes. Il serait donc étroitement associé à cette plante.

Introduction. Les variations phénotypiques et la multiplicité des dénominations des variétés marocaines de figuiers rendent confuse l’identification variétale des accessions de Ficus carica L. Matériels et méthodes. Quinze accessions présentes en collection dans la région de Meknès correspondant à cinq dénominations différentes ont été caractérisées en combinant deux approches : pomologique et moléculaire (SSR et ISSR). Résultats. Les résultats obtenus ont permis d’identifier des accessions distinctes et des redondances au sein de chacune des cinq dénominations. Conclusion. La complémentarité des deux approches se révèle utile pour l’établissement d’une collection de référence.

Introduction. Adansonia digitata L. est une espèce à usages multiples en Afrique qui présente une forte variabilité morphologique. Nos travaux ont cherché à caractériser et à mesurer cette variabilité morphologique dans différentes zones climatiques prospectées au Bénin, puis à construire des modèles prédictifs de variables de production à partir de caractères de la capsule. Matériel et méthodes. Les analyses ont porté sur une caractérisation biométrique de 1200 capsules groupées en quatre différentes formes réparties dans l’ensemble de trois zones climatiques ; ces données ont été complétées par une évaluation et une modélisation de leurs productions. Résultats et discussion. Les variables les plus discriminantes de la forme des capsules de baobab et des zones climatiques prospectées ont été la longueur de la capsule, le poids de la pulpe, le poids total de la capsule, le poids de l’amande, l’épaisseur de la capsule et le rapport [longueur / largeur]. En moyenne, une capsule pèse 275 g en zone guinéenne, 273 g en zone soudano-guinéenne et 204 g en zone soudanienne ; elle produit dans chacune de ces zones 54 g, 51 g et 32 g de pulpe, ainsi que 37 g, 28 g et 23 g d’amande. Les productions moyennes en graines, amande et pulpe ont été modélisées et ajustées à des fonctions racine carrée et/ou logarithmique suivant les différentes zones climatiques. Conclusion. Les variables morphométriques ont permis non seulement de faire une typologie assez précise des différentes formes de capsules mais aussi d’estimer leur production à partir de modèles prédictifs. La variabilité de la production des capsules de baobab suivant différentes zones climatiques pourrait être un paramètre utile à une amélioration génétique de l’espèce répondant aux besoins et aux moyens des populations rurales.

Introduction. The distribution of shoots and fruits in the tree is an important consideration to improve peach cropping. Therefore, the effects of intensity of pruning were investigated for two years in trees with the same fruit load and, the following year, in trees with different fruit loads. Materials and methods. In an early-maturing peach orchard (cv. Alexandra), three pruning intensities were applied for three years: light, medium and severe. The first two years, the same fruit load was applied for the different pruning treatments; in the last year, three fruit loads per tree were tested: low, intermediate and high. Results and discussion. Increasing severity of pruning stimulated average fruit weight and fruit diameter, limiting (2nd year) or not (3rd year) fruit yield. Severe pruning also tended to enhance young shoot growth on the shoot bearing fruit and on the scaffold branch. Fruit diameter improvement with severe pruning might be therefore explained by the increase in vegetative growth likely to enhance available assimilates for fruit growth. However, severe pruning could favor an alternation in flower setting, as observed in the 2nd year. Increasing fruit load stimulated fruit yield, but, with the highest fruit load, no significant fruit yield enhancement was detected compared with the intermediate fruit load. On the contrary, average fruit weight and fruit soluble solids always decreased with increasing fruit load. Conclusion. Intensity of pruning and fruit load must be well adapted to ensure an appropriate peach production; excessive pruning and fruit load of an early-maturing peach cultivar should be avoided in order not to limit fruit yield and quality, respectively.

Introduction. Vegetative and fruit growth in fruit trees are differentially sensitive to water deficit during the season depending on the stage of fruit growth. Attempts have been made to evaluate the possibilities of using regulated deficit irrigation to control vegetative growth and save water in the fruit industry. Materials and methods. Effects of water stress (WS) and crop load (CL) on fruit growth and carbon assimilation rates were evaluated in a 7-year-old ‘Elegant Lady’ peach orchard. A completely randomized block design with 2 × 3 factors [irrigation with two levels (control and WS) and CL with three levels (light, commercial and heavy)] was used. Results and discussion. Both WS and CL affected fruit growth during the last stages but not early on. CL did not affect trunk water potential which was, however, significantly reduced by WS throughout the day and the season. Trunk water potential of water-stressed trees was lower than that of control trees throughout the day and the season regardless of CL. The magnitude of WS increased as the season progressed. Stomatal conductance, transpiration rate and CO2 assimilation rate were not affected by CL but were reduced by WS. The trees responded (acclimated) to stress by progressively reducing their transpiration rate as the severity of stress increased. For each irrigation regime, assimilation rates were similar for all three crop levels. This indicated the existence of alternate sinks for assimilates when CL was low, which compensate for the reduction of fruit sink activity resulting from fruit thinning. Conclusion. Water deficit reduced trunk water potential, stomatal conductance, transpiration and photosynthesis in ‘Elegant Lady’ peach trees. However, CL had a limited effect on these functions. There were good correlations between trunk water potential and either stomatal conductance or assimilation rate in water-stressed trees but not in control trees. This indicates a poor coordination between leaf functions in peach trees under optimal conditions. However, these relationships were stronger under WS conditions. Thus, water use efficiency appeared to increase under water deficit conditions.

Introduction. Extraction of juice from fruit is one of the most important ways of producing fruit drinks, but the extraction rate is hindered by natural factors. This has given rise to exploration of better methods such as ohmic heating to enhance juice yield. Materials and methods. Orange (Citrus sinensis), pawpaw (Carica papaya) and tomato (Lycopercium esculentum) were ohmic-heated at 9 V dc and 110 V ac, using different electrode combinations of copper / copper (Cu / Cu) and copper / aluminum (Cu / Al) at time intervals of (5, 10 and 15) min. Juice was pressed out through a muslin cloth, and yield, pH, color and vitamin C content were determined. Structural changes in the electrode were notified, while voltage drops across the system were studied. Results and discussion. There were significant differences in juice yield according to the electrode type, the fruit type and the ohmic heating treatment time. The use of Cu / Cu electrodes at 110 V ac gave the highest juice yield; tomato yielded the highest juice content per fruit, while pawpaw yielded the least. Cu / cu-treated samples gave the worst quality in terms of color and acceptability, with indication of a high electrolysis, which dissolved the electrodes. The pH decreased with the ohmic heating treatment times. The vitamin C content significantly varied with ohmic heating time, electrode type and fruit type, and decreased in pawpaw from (63.3 to 3.91) mg·100 g–1 for Cu / Al electrodes to zero for Cu / Cu electrodes with (10 and 15) min heating. Orange retained more vitamin C irrespective of the treatment. Conclusion. The results showed that enhancement of juice extraction by ohmic heating is feasible. For commercialization of the process, the correct electrodes devoid of electrolysis must be used.

Introduction. Ficus carica L., well adapted to the Mediterranean climate, is ubiquitous in Tunisia. In spite of the large possibilities of its adaptation to the Tunisian climate, its cultivation remains traditional. In Tunisia, this species is represented by a large number of varieties which are facing genetic erosion. To save these genetic resources, we studied some of the Tunisian varieties using molecular markers. The aim of this analysis was to study the genetic diversity of some cultivars and to characterize them. Materials and methods. Six microsatellites were used to characterize 16 cultivars (Ficus carica L.) belonging to two fig tree collections in the south of Tunisia. Results. The molecular markers used appeared highly polymorphic in common fig trees since 4–12 alleles per locus and a mean of heterozygoty of 0.656 were scored. The resolving power (Rp ) of the six microsatellites tested ranged from 2.12 to 3.87 for the 16 cultivars studied, showing a significant genetic diversity (Ht = 0.762). Genetic differentiation between geographical groups was low (Gst = 0.032). The factorial correspondence analysis showed no well-defined relation between the 16 cultivars and their geographical origin. The genotype patterns allowed us to discriminate all of the cultivars. Conclusion. The characterization of the accessions belonging to different varieties was possible, showing the power and efficiency of the molecular tools used.