Effet de la Saison de Culture et de la Densité des Plants sur les Adventices et la Production de la Cucurbite oléagineuse Citrullus lanatus (Thunberg) Matsum. & Nakai (Cucurbitaceae)

Citrullus lanatus a été cultivée sur 2 périodes de l’année (saison 1 : d’Avril à Juillet et saison 2 : de Septembre à Décembre 2006) à la ferme expérimentale de l’Université d’Abobo-Adjamé en Côte d’Ivoire. Ces études visaient à déterminer la densité de la cucurbite qui assure un contrôle biologique des adventices et celle qui permet une meilleure productivité de cette culture mineure. Le dispositif expérimental est un bloc complètement randomisé, subdivisé en parcelles élémentaires de 6 m × 6 m avec trois répétitions par traitement. Sept paramètres agronomiques chez la cucurbite et la densité d’adventices (estimée uniquement au cours de la 1ère saison) ont été analysés dans trois systèmes culturaux. L’analyse a été suivie de tests de comparaisons multiples. Il en ressort que l’augmentation de la densité de la cucurbite réduit le nombre d’adventices. Les résultats montrent également que les composantes de rendement de la cucurbite, excepté le nombre de fruits à l’hectare (NFHa), diminuent avec la densité de semis. Cette diminution est plus prononcée à la deuxième saison. Sur la base des résultats obtenus, il a été suggéré de cultiver C. lanatus, à forte densité pour lutter contre les adventices et à faible densité pour obtenir des effets bénéfiques au niveau de son rendement.Mots-clés : Citrullus lanatus – densité – adventives – rendement

Evaluation De Quelques Descripteurs Morphologiques Des Populations De Teck (Tectona Grandis L. F) Verbenaceae De La Foret Classee De La Tene (Côte D’ivoire)

Dans le cadre de l’évaluation des ressources génétiques du teck, des études de diversité morphologique ont été entreprises sur les populations introduites à la Téné en Côte d’Ivoire. L’objectif est d’évaluer la variabilité de certains descripteurs afin d’identifier les plus discriminants. Les analyses ont porté sur cinq variables quantitatives (la hauteur totale des arbres, la circonférence du tronc à 1,30 mètre du sol, la présence de fourche, l’index de bosses et bourgeons, et la rectitude axiale) liées à l’architecture de l’arbre. Ces cinq caractères ont permis de cribler 445 individus appartenant à 10 populations. A l’exception de la rectitude axiale de l’arbre, toutes les autres variables permettent de distinguer des classes phénotypiques bien distinctes. Ainsi l’analyse de sa diversité génétique a permis de retenir la circonférence de l’arbre, l’index de bosse et de bourgeons, et la hauteur totale de l’arbre comme étant les variables biométriques qui caractérisent le mieux les populations de teck. Cette étude a également permis d’identifier les populations Bigwa (Tanzanie) et de Masale valley (Inde du sud) comme étant les plus performantes. Outre ce résultat, les Analyses en Composantes Principales (ACP) montrent que les variables contribuent à la révélation de 71,62 % de la variabilité totale sur les deux axes principaux. La Classification Ascendante Hiérarchique (CAH) a permis de typer les populations en trois groupes.Mots clés : Classification, Côte d’Ivoire, diversité génétique, Tectona grandis, descripteurs morphologiques. As part of an evaluation of genetic resources of teak, studies of morphological diversity were carried out on the populations of Téné in Côte d’Ivoire. The objective of this study was to evaluate the variation in descriptors in order to identify those which give the best discrimination. The analyses were carried out on five quantitative variables (the total height, the circumference, the fork; the bumps and buds index, and the straightness) related to the structure and shape of the tree. Five characters are allowed to screen 445 individuals belonging to 10 populations. All the variables studied were able to distinguish phenotypic classes among individuals in the population. This study showed that the circumference of the shaft, bump index and buds, and the total height of the tree are the most discriminant characters. The biometric characters identified Bigwa (Tanzania) and Masale valley (India) as the most performant populations. The results of Principal Component Analysis (PCA) show that the variables accounted for 71.62 % of the variation in the first two principal axes. TheHierarchical Ascendant Classification has allowed the characterization of teak populations. On the other hand, this study allows us to clarified origin of Tové (Togo) population. It was from North India.Key words : Classification, Côte d’Ivoire, genetic diversity, morphological descriptors, Tectona grandis. Article in French

The Impact of Socio-Demographic and Religious Factors upon Sexual Behavior among Ugandan University Students

INTRODUCTION: More knowledge is needed about structural factors in society that affect risky sexual behaviors. Educational institutions such as universities provide an opportune arena for interventions among young people. The aim of this study was to investigate the relationship between sociodemographic and religious factors and their impact on sexual behavior among university students in Uganda. METHODS: In 2005, 980 university students (response rate 80%) were assessed by a self-administered questionnaire. Validated instruments were used to assess socio-demographic and religious factors and sexual behavior. Logistic regression analyses were applied. RESULTS: Our findings indicated that 37% of the male and 49% of the female students had not previously had sex. Of those with sexual experience, 46% of the males and 23% of the females had had three or more sexual partners, and 32% of the males and 38% of the females did not consistently use condoms. For those who rated religion as less important in their family, the probability of early sexual activity and having had a high number of lifetime partners increased by a statistically significant amount (OR = 1.7; 95% CI: 1.2-2.4 and OR = 1.6; 95% CI: 1.1-2.3, respectively). However, the role of religion seemed to have no impact on condom use. Being of Protestant faith interacted with gender: among those who had debuted sexually, Protestant female students were more likely to have had three or more lifetime partners; the opposite was true for Protestant male students. CONCLUSION: Religion emerged as an important determinant of sexual behavior among Ugandan university students. Our findings correlate with the increasing number of conservative religious injunctions against premarital sex directed at young people in many countries with a high burden. of HIV/AIDS. Such influence of religion must be taken into account in order to gain a deeper understanding of the forces that shape sexual behavior in Uganda

Feedstuffs potential of harvest by-products from two oleaginous curcurbits

Among the generated crop residues and by-products in tropical agriculture, those of cucurbits represent great opportunities for animal nutrition. Nutritive profile of harvest by-products (dried leaves, fermented fruits, non fermented fruits and seeds shells) of two oleaginous cucurbits (Citrullus lanatus and Lagenaria siceraria) were investigated in order to explore their potential use as feedstuffs. The moisture, ash, and crude fibres contents were 4.81 to 12.87, 9.93 to 18.29, and 2.18 to 16.35%, respectively. Shells of L. siceraria seeds yielded the highest carbohydrate content (84.80 ± 2.78 %) while the highest calorific value (380.92 ± 11.40 kcal/100 g) was obtained in C. lanatus bebu. The contents of threonine (Thr), lysine (Lys) and methionine (Met) in dried leaves of C. lanatus bebu were 4.16, 6.86 and 6.89 g/100 g proteins, respectively. The content of methionine (Met) was 5.81 g/100 g proteins in fermented fruits of C. lanatus (wlêwlê). The harvest by-products analyzed in this study contained remarkably high amounts of potassium (671.78 – 4738.79 mg/100 g) and calcium (342.08 – 2963.95 mg/100 g) with highest value (4738.79 ± 230.10; 2963.95 ± 135.74 mg/100 g) for non-fermented fruits of L. siceraria and dried leaves of C. lanatus wlêwlê, respectively. The analyzed plants parts were also notable sources of magnesium, ranging from 221.45 ± 1.96 mg/100 g (non-fermented fruits of L. siceraria) to 872.10 ± 48.49 mg/100 g (dried leaves of C. lanatus wlêwlê). All these results suggest that the studied by-products could be used as valuable feedstuffs. Key words: Harvest by-products, nutritive value, cucurbits, feedstuff

Effet des dates de semis sur la performance agronomique de Lagenaria siceraria (Molina) Standl. (Cucurbitaceae) et Manihot esculenta Crantz (Euphorbiaceae) en culture associée

Effect of sowing dates on the agronomic performance of the intercrops: Lagenaria siceraria (Molina) Standl. (Cucurbitaceae) and Manihot esculenta Crantz (Euphorbiaceae). Description of the subject. The intercropping system is a beneficial method, which is widely used in tropical areas for sustainable soil fertility management, and has been found to improve both the yields of traditional agriculture and the income of small producers. Objectives. The aim of this study was to compare and evaluate the effect of associated culture and pure culture of cucurbit Lagenaria siceraria creeping plant and the variety of cassava Manihot esculenta var. 'Bonoua Blanc' upright plant on the agronomic performance of each crop. Method. An experiment was established in randomized complete block design with three replicates per treatment. The treatments compared were firstly, associated crops M. esculenta var. 'Bonoua Blanc' / L. siceraria with cucurbit seedlings at 0 days (CAT0), 15 days (CAT15), 30 days (CAT30) and 45 days (CAT45) after cassava; secondly, pure cultures of cucurbit on the same dates as for associated crops (CPT0, CPT15, CPT30 and CPT45), and thirdly, a pure culture of cassava at 0 days (CP). Nine agronomic characteristics were analyzed in cucurbit and eight in cassava. Results. The agronomic parameters evaluated were the yield components of cassava, which varied with the increase in seedling time of cucurbit. However, the performance of cucurbit decreased with the increase in seedlings either in the associated crop or in pure culture. Performance also decreased sharply for the same sowing dates in pure culture. Despite high productivity when cucurbit was simultaneously planted with cassava, it remained low compared to the cucurbit pure crop. Conclusions. Intercropping of cucurbit L. siceraria and cassava M. esculenta was not found to be beneficial to the yield of the individual crops. However, the use of cucurbit as an intercropping cover crop helps to conserve soil moisture and to manage arable land and weeds for the benefit of cassava crops

Morphological and allozyme variation in a collection of Lagenaria siceraria (Molina) Standl. from Côte d'Ivoire

This study describes the intraspecific variation of 30 edible-seed Lagenaria siceraria germplasm accessions from the University of Abobo-Adjamé. These accessions were collected from three (Centre, East and South) geographical zones of Côte d’Ivoire. Selection based on seed size by the farmers has resulted in subdividing the species into two cultivars: large-seeded and smallseeded. The morphological diversity study of the collection included 18 accessions and 24 traits. The multivariate analysis of variance (MANOVA) showed a significant difference between the two groups of cultivars. Principal component analysis on 13 traits pointed out variations among individuals, mainly on the basis of flower, fruit, and seed size. Dendrogram with UPGMA method allowed clustering of the cultivars. The genetic structure analysis among accessions using allozyme markers showed the following values: 18.95% for the proportion of polymorphic loci (P), 1.21 for the number of alleles (A) and 0.053 for observed heterozygosity (Ho). The level of the within accessions genetic diversity (HS = 0.188) was higher than the genetic variation among accessions (DST = 0.082). The estimates of F-statistics indicated a low level of genetic differentiation between accessions (FST = 0.298). Such a value suggested that L. siceraria maintains about 30% of its genetic variation among accessions. Nei genetic distances between the two cultivars were also low (0.002), indicating that cultivars were genetically similar enough to belong to the same genetic group

A short history of Lagenaria siceraria (bottle gourd) in the Roman provinces : morphotypes and archaeogenetics

Mitteleuropa - Flaschenkürbis - Chloroplast DNA - Morphologie - Herkunftsbestimmung - Impor