www.tjprc.org editor@tjprc.org PRODUCTIVITY OF NEW YAM ASSESSIONS AS AFFECTED BY MOSAIC VIRUS IN TRANSITION FOREST-SAVANNA ZONE OF CÔTE D'IVOIRE ETTIEN DJECTHI JEAN BAPTISTE 1 , SORHO FATOGOMA 2 , BRAHIMA KONE 3 , YAO-KOUAME ALBERT 4 & GIRARDIN OLIVIER 5 1,3,4 Department of Soil Sciences, University Felix Houphouet-Boigny Abidjan, Côte d’Ivoire 1,2,5 Department of Biodiversity and Food Security, Centre Suisse de Recherches Scientifiques, Abidjan, Côte d’Ivoire 2 Laboratory of Plant Physiology, University Felix Houphouet-Boigny Abidjan, Abidjan, Côte d’Ivoire ABSTRACT Yam is being a strategic crop for food security in West Africa. However, there are many constraints that limit its productivity. Among the constraints, we have low quality of seeds and pest pressure. Therefore, there is a need to assess the tolerance of new cultivars released, especially for yam mosaic virus (YMV) wide spreader in yam agro-ecologies. During the cropping seasons of 2000 and 2001, a trial was conducted in augmented design including sixteen varieties of yam in four replications according to a density of 30000 plants per hectare. The checks were the local varieties named Bete bete and Florido. The severity effect of YMV was measured at 2, 4 and 6 months after planting. The results showed a significant effect of YMV on check cultivars and some improved varieties in 2000 and 2001 as well as significant correlation between canopy surface rate and yields. Highest yield (32 t/ha) was obtained in 2000 by the improved variety 98_01176 among eight tolerant cultivars while 14.9 t/ha was recorded for the local cultivar Bete bete. These best varieties could be recommended to farmers to increase their production in a sustainable cropping system. KEYWORDS: Yield, Yam Mosaic Virus, Yam Assession, Canopy Surface Rate, Côte d’Ivoire INTRODUCTION Yam (Dioscorea spp) is important for food security in West Africa producing more than 90% of the worldwide production (FAO, 2009). Besides its importance as food source, yam also plays a significant role in the socio-cultural lives of people in some producing regions like the celebrated New Yam Festival in West Africa (Osunde and Orhevba, 2009) and wedding ceremonies in Oceania (O'Sullivan and Ernest, 2008). Cultivated yams belong to the Dioscoreceae and the genus Dioscorea families. There are also species of wild yam growing in Côte d’Ivoire whose tubers are collected for eating in times of food shortage. Yam is a valuable source of carbohydrate to the people of the tropical and subtropical Africa, Central and South America, parts of Asia, the Caribbean and Pacific Islands (Adelusi and Lawanson, 1987). Yam is subject to the depredations of several pests reducing production. The Yam Mosaic Virus (YMV) genus Potyvirus, from the family of family Potyviridaeis is the most important virus infecting both cultivated and wild yams especially Dioscorea rotundata, D. alata, D. cayenensis and D. praehensilis in the yam-growing areas of the world (Thouvenel and Fauquet, 1979; Porth et al., 1992). The Yam Mosaic Virus is reported in the growing regions of Nigeria, Ghana, Cameroon, Benin, Côte d’Ivoire, Burkina Faso and Togo in West Africa (Porth et al., 1992; Thottappilly, 1992; Brunt et al., 1996). According to International Institute of Tropical Agriculture-IITA (IITA, 1981), YMV causes several symptoms including mottling, leaf International Journal of Agricultural Science and Research (IJASR) ISSN(P): 2250-0057; ISSN(E): 2321-0087 Vol. 4, Issue 3, Jun 2014, 137-146 © TJPRC Pvt. Ltd