Introduction. The objective of the present paper was to evaluate the effects of N, P and K, and their interactions, on fruit yield and quality of two sweet orange varieties, Valencia and Pêra, grown on tropical soils in the State of São Paulo, Brazil, over four seasons. Materials and methods. Two experiments were set up in a fractional factorial design of the ½ (4 × 4 × 4) type, with four rates of N [(30, 100, 170 and 240) kg·ha–1·year–1], P [(9, 27, 45 and 63) kg·ha–1·year–1)] and K [(24, 91, 158 and 225) kg·ha–1·year–1] applied to the soil surface during the rainy season. Functions of the type y = b0 + b11 N + b11 N2 + b2 P + b22 P2 + b3 K + b33 K2 + b12 NP + b13 NK + b23 PK were fitted for dependent variables: fruit yield and mass, juice content, and total soluble solids and acidity concentrations. Results. Maximum yield of Pêra and Valencia was attained, respectively, with N rates of (189 and 193) kg·ha–1. Fruit yield response to P and K fertilization for both cultivars was dependent on soil nutrient availability. Fruit size of Valencia trees was markedly affected by rates of K over 225 kg·ha–1. Yield of soluble solids per box of fruits (40.8 kg) decreased as leaf K concentration varied from (10 to 12) g·kg–1. Conclusion. Soil testing and leaf analysis play an important role in defining fruit yield and quality for citrus trees. The best nutritional program may vary depending on the destination of fruit to either juice production or the fresh market.

Introduction. Le karité a une fructification aléatoire. L’objectif de notre étude a été de tester la technique d’incision annulaire comme outil de contrôle de cette fructification irrégulière. Matériel et méthodes. En août 2003, une incision annulaire portant sur les trois quarts du pourtour d’une branche a été effectuée, jusqu’à l’aubier, sur 29 karités du terroir de Bondoukuy (Burkina Faso) ; une branche de chacun de ces mêmes arbres a servi de témoin. En 2004, un essai factoriel d’incision a été entrepris ; il a porté sur deux sites de ce même terroir, deux périodes de traitement (fin août et fin novembre), trois ampleurs d’incisions (50 %, 75 % et 100 %) et cinq karités utilisés par traitement. Ce sont donc 60 karités multicaules qui ont été étudiés, un des troncs de chacun d’eux servant de témoin. La proportion de rameaux florifères (%rFl) et le nombre de fleurs (nFl) et de fruits (nFr) formés par rameaux traités et témoins ont été comptabilisés puis analysés. Résultats. Par rapport aux branches témoins, l’incision annulaire a accru de 17 % le (%rFl), 54 % le (nFl) et 100 % le (nFr) par rameau. Les périodes et ampleurs d’incision testées n’ont pas montré de différences entre elles, mais elles ont permis aux branches traitées d’obtenir un (%rFl) supérieur à celle des branches témoins. Quelle que soit la variable considérée, il est apparu une différence de performances de reproduction entre les karités des sites testés ; l’efficacité de l’incision annulaire serait donc liée aux conditions édaphiques de développement de l’arbre. Discussion et conclusion. La technique d’’incision annulaire peut donc être utilisée pour contrôler l’irrégularité de la fructification du karité. Néanmoins, des études complémentaires se révèlent indispensables pour déterminer l’effet de la période de l’incision sur le grossissement et la composition chimique des fruits.

Introduction. To facilitate establishment of pitaya (Hylocereus undatus) cultivations in new areas, factors affecting its propagation by cuttings and seeds were studied. Materials and methods. Firstly, cuttings of (5, 15 and 25) cm length were tested in three substrates: peat moss (pm), peat moss and sand mix(1:1) (pm/sa) and sand (sa). Indole-3-butyric acid (IBA) solutions were prepared at [0, 5, 10 or 15] mM dissolved in 70% ethanol. After the basal cuttings were dipped for 10 s in these IBA solutions, cuttings were planted in (pm/sa). After (1, 2 or 3) weeks, the cutting rooting, number and length of the developed roots were measured. Moreover, germination was tested at four temperatures [(16, 20, 24 and 28) °C] by placing seeds on wetted filter papers in Petri dishes. Light effect was tested at four white light intensities of (0, 500, 1000 or 2000) lx. Seed viability was tested at 24 °C in darkness with 1000 seeds. The effect of (pm), (pm/sa) and (sa) was tested on germination and seedling growth. The percentage of germination, days to emergence and growth rate of seedlings were measured. Results and discussion. After two weeks, 25-cm pitaya cuttings rooted successfully in the three substrates, but the number and length of the developed roots were affected by the type of substrate. A significant effect of cutting size on root initiation, and number and length of the developed roots was found. IBA consistently improved rooting percentage and root number and length. Overall, 5-cm-long cuttings treated with IBA (10 mM) could be efficient at propagating pitaya. The seed viability was 83%. Germination, which varied between (71 and 83)% depending on the temperature, began after 6 days at (24 and 28) °C. Light intensity at (1000 or 2000) lx reduced seed germination. Potted seedlings grew successfully in the greenhouse.

Introduction. Fruit flies (Diptera, Tephritidae) are among the major constraints in commercial horticulture in many African developing countries. Knowledge of the tephritid spectrum in any given area is a prerequisite for the development of an IPM program to alleviate the pest problem. We studied the fruit fly diversity in four main agro-ecological zones which are significant fruit-producing areas in the Morogoro Region, Tanzania. Materials and methods. Fruit fly diversity was investigated for one year (October 2004 – October 2005). Parapheromones, synthetic food attractant and protein-bait traps were used to trap the flies at the different locations in Morogoro region, Tanzania. One mixed orchard was selected at each of four locations representing the different agro-ecological zones of the region. Results. The recently introduced alien species, Bactrocera invadens, and three indigenous pest species, Ceratitis rosa, Dacus bivittatus and D. punctatifrons, were found at all the four sites, while Bactrocera cucurbitae, Ceratitis cosyra, Dacus chiwira and D. humeralis were found in three out of the four sites. The Sokoine University of Agriculture (SUA) Horticulture Unit and Mikese sites had the highest species diversity while the Mkindo and Nyandira sites had the lowest diversity. The between-habitats diversity (Beta diversity) was similar among the SUA, Mkindo and Mikese sites. Only the Nyandira site had a higher dissimilarity in comparison with the other three sites. Discussion. The most abundant species at low- and mid-elevation sites was Bactrocera invadens while, at high elevation, Ceratitis rosa was the dominant species. Protein-baited traps attracted the highest diversity of fruit flies in comparison with the more specific parapheromones. The synthetic food attractant (three-component lure) was less efficient compared with the protein bait. The large dissimilarity at the Nyandira site is probably due to the different types of host fruits found and grown in high altitude areas (mainly temperate fruits). Fruit fly species associated with these types of fruits, e.g., Ceratitis rubivora and Trirhithrum coffeae, were found only at this site.

Introduction. The aim of our study was to evaluate the effects of sugar and citric, malic, succinic and ascorbic acid levels on melon flavor perception, and to infer about consumers’ preferences based on instrumentally measured characteristics. Materials and methods. Fully ripened melons belonging to the ‘Branco’ (Brazilian), ‘Pele de Sapo’ (Spanish) and winter ‘Tendral’ (Portuguese) melon cultivars were analyzed using five fruits with three replicates for each treatment. Quality parameters (weight, height, diameter, solid shape, volume, internal appearance, texture and flavor), sugars (glucose, fructose and sucrose), total soluble solids content, sweetness, organic acids (citric, malic, succinic and ascorbic) and sourness were measured. Results and discussion. Flavor was the most important parameter for the consumers’ decision, regarding the different melon cultivars studied. It was also detected that it correlated well with sweetness (thus, with sucrose content) and sourness. The obtained data supports that sugars and organic acids enhance human perception of specific flavor notes in melon.

Introduction. Information correlating leaf nutrient contents to fig tree yield is still rare in Brazil. The objective of our research was to evaluate the effect of fertilization with boron and cattle manure on fig tree productivity and the leaf and fruit nutrient contents, and to estimate the extraction of nutrients by the crop. Materials and methods. The treatments consisted of five boric acid levels [(0, 20, 40, 60 and 100) g per plant] combined with two levels of cattle manure [(0 and 10) kg per plant]. The experimental design was in randomized blocks in a split-plot scheme with four replicates. The cattle manure levels constituted the plots, and the boron levels the subplots. We studied tree productivity, macronutrient and micronutrient leaf and fruit contents, amounts of nutrients extracted per ha and per crop yield, and fig tree leaf and fruit dry matter nutrient contents as a function of sampling dates. Results. Fruit yield productivity, average fruit weight and number of fruits per tree were not affected by B fertilization but they were by cattle manure levels, which increased the fig tree productivity. The macronutrient and micronutrient leaf and fruit contents obtained are discussed in relation to Brazilian results already published. The levels of cattle manure did not significantly affect the amount of nutrients extracted from green fig yield. The Mn, Zn and B leaf contents and the fruit extraction of Mn and B increased linearly with boric acid levels. The fig tree leaf nutrient contents varied with the plant physiological stages during its production cycle. Conclusion. These results should be taken into account for the development of fig tree fertilization programs in Brazil.