RESUMECette étude a été conduite à la Faculté d'Agronomie de Niamey au Niger. Elle vise, à travers la mesure des paramètres biométriques et pondéral, à sélectionner des semences de Jatropha curcas présentant de bonnes aptitudes à la germination. La longueur, la largeur et le poids moyens des fruits sont respectivement de 2,55 cm ± 10% ; 1,90 cm ± 13,2% et 1,83 g ± 45,36%. Le poids d'un fruit est fortement corrélé à sa longueur et à sa largeur (r =.0,83 et 0,82). La classification des fruits montre que 19,94% sont petits, 62,88% moyens et seulement 17,17% de gros fruits. La largeur, l'épaisseur et la longueur moyennes des graines sont respectivement de 1,10 cm ± 5,5% ; 0,84 cm ± 7,14% et 1,77 cm ± 5,65%. La moyenne du poids d'une graine étant de 0,498 g ± 38,15%. Selon le poids, 20,53% des graines sont petites ; 60% sont moyennes et 19,47% sont grosses. Les caractéristiques de germination au laboratoire et celles de la levée en pépinière sont meilleures pour les grosses graines par rapport aux graines moyennes et petites. Cette étude a permis de distinguer les semences de Jatropha curcas qui offrent les meilleures aptitudes de germination et de levée. Mais, avant toute diffusion, il est nécessaire de poursuivre cette investigation afin d'apprécier la répercussion des différences observées sur tout le cycle de développement de la plante. © 2016 International Formulae Group. All rights reserved.Mots clés : Biocarburant, effet de serre, système agraire, agroforesterie, séquestration carbone, haie vive Screening and seed germination characteristics of Jatropha curcas L. (Euphorbiaceae) in experimental condition in Niger ABSTRACTThis study was conducted at the Faculty of Agriculture, UAM Niamey, Niger. It focuses on measuring the biometric parameters and weight, to select Jatropha curcas seeds with good germination capabilities. Length, wide and weight averages of fruits are respectively 2.55 cm ± 10% ; 1.90 cm ± 13.2% and 1.83 g ± I. CHAIBOU et al. / Int. J. Biol. Chem. Sci. 10(2): 749-759, 2016 750 45.36%. The weight of a fruit is highly correlated to its length and wide (r = 0.83 and 0.82). Classifications shows 19.94% of fruits are small, 62.88% are medium and only 17.17% are thick. Wide, thickness and length averages of seeds were respectively 1.10 cm ± 5.5% ; 0.84 cm ± 7.14% and 1.77 cm ± 5.65%. The weight average of seed was 0.498 g ± 38.15%. Accordingly, the weights (20.53%) of seeds were small, 60% were medium and 19.47% were thick. The laboratory assey on germination characteristics and those of the lifting nursery were best for larger seeds compared to medium and small seeds. Thus, this study helped to distinguish Jatropha curcas seeds with best capabilities of germination and emergence. But before distribution, it is necessary to go on with the investigation in order to assess the impact of differences throughout the plant life cycle.

The present study is conducted in the Sylvo-Pastoral Zone (ZSP) of the Goulbi N'Kaba Valley and the agricultural zone (fields on adjacent terraces), in the southern center of Niger. The objective of the study is to evaluate the inter-decennial plant biodiversity (2004-2014). Thus, the phytosociological surveys (Daget and Poissonet, 1971) were carried out in plots of 2500 m², along the 6.5 km transects following stratified sampling. An ascending hierarchical classification, followed by an ordination by Nonmetric Multi-dimensional Scaling (NMS) allowed to identify the plant groups. The diversity of each group was evaluated. The results show that the families of Poaceae and Fabaceae are the most abundant in 2004 (15.58% and 11.69%) and in 2014 (18.75% and 7.29%). However, compared to the genera, Indigofera (10.53%), Cassia (6.58%), Acacia (5.26%), Aristida (5.26%) are the most abundant in 2004, while Aristida (4 , 17%), Cassia (4.17%), Spermacoce (3.13%), in 2014. Three groups (mixed, fields, ZSP) have been identified. The 2004 and 2014 index, of Margalef (18,38 and 11,28), Menhinick (2,55 and 1,52), Shannon-Weaver (4,77 and 4,14), the fairness of Pielou (0, 66 and 0.63), the Simpson index (0.89 and 0.91) and Hill (0.95 and 0.93) are high in all the groups, mixed, fields and ZSP (respectively for G1, G2 and G3). But the beta diversity (Whittaker (24), Jaccard (0.52), Sorensen (0.69) index) for each of these groupings remains low. There was no significant change in inter-decennial diversity at the Guidan Tawayé and Korin Habdjia sites from 2004 to 2014.