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Aflatoxin contamination in groundnut byAspergillus flavus has assumed global significance and is considered a potential threat to human and animal health. The present study focused on the screening and identification of stable and reliable resistance sources to pre-harvest aflatoxin contamination in ICRISAT's groundnut mini core germplasm accessions. . In total, 31 accessions had less aflatoxin accumulation than the resistant check, 55-437. The seven best accessions, ICGs 13,603, 1415ICGs 13,603, , 14,630, 3584, 5195, 6703 and 6888, over six years (2008ICGs 13,603, -2013 consistently accumulated very low levels of aflatoxin (<4 μg kg −1). These seven accessions could be potential sources for understanding the resistant mechanisms and can be further used in developing resistant cultivars or introgressing resistance in popular released varieties.

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REMERCIEMENTS Nous adressons nos sincères remerciements aux responsables de l'ITRAD, au PRASAC et à l'UE pour la bourse qui nous a été accordée pour ce travail. RESUMEDans les petites exploitations familiales, les paysans détiennent un nombre important de cultivars de manioc inexploités par la recherche. L'objectif de cette étude est d'évaluer le niveau de la diversité du manioc et d'en analyser les pratiques locales de gestion. Une enquête suivant une approche participative avec des questionnaires a été conduite auprès de 636 paysans dans 43 villages. Une importante diversité variétale a été révélée par l'indice de Shannon (3,38). Soixante-quinze noms vernaculaires ont été inventoriés. Des différences hautement significatives ont été observées pour le nombre de cultivars qui varie de 2 à 12 par village (6 en moyenne). La variation entre ménages est faible, 1 à 4 cultivars (2 en moyenne). Le nombre de cultivars disparus varie de 1 à 14 (3,81 en moyenne) par village. La perte de la diversité est en moyenne de 18,20% et varie entre 11% et 50% selon les villages. Les paysans identifient les cultivars à partir des feuilles et tiges. La productivité, le goût et la grosseur des tubercules sont les critères prioritaires de sélection. Les échanges des boutures se font entre paysans locaux (60,84%) et par des introductions individuelles (37,43% Farmer management of cassava cultivars (Manihot esculenta Crantz)in the South of Chad D. NADJIAM et al. / Int. J. Biol. Chem. Sci. 10(3): 1098-1113, 2016 1099 ABSTRACTFarmers possess in their fields, many cassava cultivars which are unexplored by the research. The aim of this study is to assess their diversity and to analyze their traditional management. A total of 636 farmers selected from 43 villages, were surveyed using questionnaire and participatory rural appraisal. ShannonWeaver diversity index (H) revealed an important level of diversity of 3.38 in the study zone. Seventy-five (75) vernacular names were recorded. Highly significant differences were observed for the number of the cultivars that ranges from 2 to 12 per village (6 on average). At household level, the variation is low and ranged from 1 to 4 cultivars (2 on average). The number of disappeared cultivars range from 1 to 14 (3.84 on average) per village. The average rate of diversity loss is 18.20% and ranging from 11% to 50% per village. Farmers use leaves and stems to identify cultivars. High yield root, taste and large sized rate were the farmer preferred criteria. The exchanges of the stems are done among local farmers (60.84%) and by individual initiatives (37.43%). This knowledge will be integrated in the breeding program.

The objective of this study is to assess the response of five varieties of sweet maize namely, Prime plus (V1), Shy 1036 (V2), Colombus (V3), GSS (V4), and JKMH-45 (V5) to three different doses of NPK (15-15-15) fertilizer: F1 (normal dose), F2 (75% of the normal dose) and F3 (125% of the normal dose). An experimental design in Fisher blocs with 15 treatments was established at the ISRA/CRA experimental station in Saint Louis European Scientific Journal September 2016 edition vol.12, No.27 ISSN: 1857 (75% of the normal dose). The F3 dose increases less the plant's height. A non-significant difference was observed among the 5 varieties used regarding the precocity. The variety V2 or Shy 1036 developed ears at first, but is not precocious compared to the variety V1 that not only shows earlier anthesis but also an appearance of darker hairs. The variety JKMH-45, although presenting darker hairs after the variety Prime plus, is the latest variety, earing at 57 DAS and with male and female anthesis appearing at 59 DAS and 63 DAS. This study can constitute a basic criterion in differentiating the sweet maize varieties in Senegal. It would also allow more financial saving on inputs and contribute to the maximization ofproduction if the choice of the variety is well done.