Introduction. A project was undertaken to study the nutrient cycling from Musa mother plants to daughter suckers based on the physiological stages of the mother plant. It also reports on the dependency or competition at critical stages of flowering and fruiting and the combinations of different densities and sucker retention at different physiological stages of the mother plant. Materials and methods. A combination of three spacings and five sucker retention phases formed 15 treatments. 32P was given through injection into the mother plant pseudostem. The experiment was carried out over two years, the first being a rain-fed crop and the second being under irrigated conditions. Results. Differential aspects of nutrient cycling were observed between rain-fed and irrigated crops with regard to spacing. In the case of sucker retention phases, in the first year, it was retention at fruit maturity, shooting and flower bud differentiation stages which showed higher radioactivity recovery whereas, in the second year, it was the early phases of retention which showed significantly higher recovery. In the case of interaction effects, in the first year, the highest recovery was found in various combinations of spacing with the stages of bud initiation and shooting and, in the second year, the maximum recovery observed was in the combination of the closest spacing with the stage of flower bud initiation. In both years, recovery was observed in the border row plants. Conclusion. The study confirmed that activity extruded out from the treated plant and was absorbed by the border plants, revealing that nutrient sharing takes place in banana. This result opens up another concept that banana recommendation should not only be at an individual plant level but at block or plot level also. Hastening and improving the efficiency of nutrient cycling to the sucker is suggested as a future line of investigation.

Introduction. Cytokinins enhance axillary shoots, which helps prolific shoot multiplication in vitro. Very few reports are available on biochemical changes associated with this in vitro proliferation of Citrus. The present study was undertaken to find out the influence of two widely used cytokinins on various morphological and biochemical constituents of in vitro proliferated shoots of Citrus species. Materials and methods. Shoots of (0.5 to 1.0) cm long from in vitro proliferated shoots of five Citrus species were cultured on MS medium supplemented with eight increasing levels of benzylaminopurine (BAP) or kinetin spread from (0.25 to 2) mg$\cdot$L-1. After 6 weeks of culture, morphogenetic characters were observed, and shoot samples were crushed with 5 mL of hot ethanol; the extract collected was used for the estimation of reducing sugars, total phenols, ortho dihydric (OD) phenol, amino nitrogen and protein percentages. Results and discussion. For all the morphogenetic characters studied, except the shoot number, there were significant interactions between the Citrus species and the different concentrations of BAP and kinetine. Increased concentration of cytokinins reduced the amount of total phenol, OD phenol and total protein. Calamondin recorded the lowest percent of reducing sugar and protein. The maximum amount of reducing sugars was recorded for C. volkameriana. Supplementation of BAP resulted in the highest amount of total and OD phenols, whereas kinetin improved the reducing sugar and amino nitrogen.

Introduction. Research on the mineral nutrition of Barbados cherry is scarce. Leaf sampling techniques for this crop are unknown. Leaf analysis, associated with the determination of the nutrient availability in the soil, can provide reliable orientation for the establishment of fertilizer programs. For a correct interpretation of the nutritional status, it is important (1) to evaluate the seasonal variation of nutrient contents in the leaves, (2) to determine the appropriate time for leaf sampling and analysis, and (3) to indicate the best part of the plant for determination of the nutritional status. These subjects were the three objectives of this study. Materials and methods. The experiment was conducted from March 1997 to February 1998 in Visconde do Rio Branco, Minas Gerais, Brazil. The dynamics of the elements N, P, K, Ca, Mg, S, Fe, Cu, Zn and Mn were studied in leaves at the apical, median and basal positions of branches located in the upper, median and lower portions of the plant canopy. Results. The minimum variation in the foliar contents occurred at the medium third of the branches located in the upper portion of the canopy. So, these parts are the most appropriate for leaf sampling. Moreover, December was characterized as the appropriate time for leaf sampling. Conclusion. The leaf sampling techniques developed will allow better study of the mineral nutrition of M. emarginata in order to establish reliable fertilizer programs and to improve the yields of this fruit tree.

Introduction.Zizyphus mauritiana Lam. est un arbre fruitier sauvage très commun en Afrique sahélienne. Ses fruits, les jujubes, sont traditionnellement exploités par cueillette dans les peuplements naturels et représentent une source de revenu importante pour de nombreuses familles rurales. Ils sont consommés frais ou secs. Au Sénégal, un programme d'introduction de variétés de jujubiers améliorés d'origine indienne est en cours depuis plusieurs années. L'objectif des travaux présentés a été de comparer la première variété introduite (Gola) avec deux lots de jujubes locaux. Matériel et méthodes. La comparaison entre différentes origines a porté sur les caractéristiques biométriques des fruits et sur les teneurs de la portion comestible en divers composés organiques et en éléments minéraux. L'étude a été complétée par une enquête gustative auprès de consommateurs. Résultats et discussion. La portion comestible des fruits frais de Gola est environ vingt fois plus importante (en poids et volume) que celle des jujubes locaux. La pulpe des Gola est plus riche en eau et moins concentrée en éléments organiques (sucres, protéines) et minéraux (calcium, magnésium). Cependant, après séchage, les teneurs ne sont plus significativement différentes, si ce n'est celles des protéines et de quelques éléments minéraux dont la richesse chez Gola diminue très nettement pendant le séchage. Les fruits de Gola séchés, très parfumés, ont été les plus appréciés par la population sénégalaise. Conclusion. Quelle que soit leur origine, les jujubes sont riches en sucres, en vitamines C, en calcium et en fer. Ces fruits représentent un apport nutritionnel important pour les populations des régions arides. La variété Gola répond bien au goût du consommateur sénégalais. Sa diffusion en zone sahélienne peut donc être envisagée sous réserve d'avoir levé au préalable les contraintes techniques liées à la production des plants et d'avoir vérifié la rentabilité économique de cette nouvelle culture.

Introduction. In Algeria, the Mediterranean fruit fly Ceratitis capitata Wiedmann constitutes the main obstacle to production and exportation of many fruits. In studies of the genetic structure differences of medfly populations, certain authors, using molecular markers, observed the existence of different patterns among the pest Mediterranean populations. A clear understanding of the source and migration of the Mediterranean fruit fly would be useful for undertaking a successful eradication or control program. For this reason, preliminary work sought to compare the genetic structure of Algerian populations of C. capitata with that of other populations situated either in the western Indian ocean or on the northwestern Mediterranean coast. Materials and methods. The study of enzyme polymorphism allowed the comparison of the genetic structure of four Algerian populations of Ceratitis capitata with one from Reunion Island and five other populations collected from the northwestern Mediterranean coast (France and Spain). Enzyme analyses were performed on ground pest adults electrophoresed on a starch gel. Fifteen loci were analyzed for each population. Results and discussion. In spite of a wide geographic distribution of the analyzed populations (from a latitude of 24° to 44° N), no gradient of allelic frequencies was observed for any of the polymorphic loci. A higher genetic variability was observed in the population of Reunion Island than in the populations of Algeria or the northwestern Mediterranean coast. No genetic differentiation was observed among the populations of southern Algeria (Djanet and Ghardaïa) and northern Algeria (Boufarik and Oran).