Screening of new yam clones (D. alata and D. rotundata) in nematode prone ecology of guinea savanna zone in West Africa.

Objectives: The main objective of this study was to identify some yam assessions that are tolerant to the most invasive nematodes like Scutellonema bradys and Meloidogyne spp. Methodology and results: New assessions of Dioscorea spp. were screened in the savanna zone of central C te d’Ivoire. Fourteen of D. alata and thirty seven assessions of D. rotundata were tested respectively and separately against two and four local yam varieties in an augmented design from 2000 to 2001. Nine varieties of D. rotundata were more resistant to S. bradys and Meloidogyne when D. alata were less tolerant. The effect of S. bradys on D. alata was higher in 2001 compared to 2000. The effect of Meloidogyne was significantly (P<0.001) depressive on the production of D. rotundata every year while they were tolerant to S. bradys. Conclusion and application: Identified assessions among D. rotundata can be considered as promising varieties in nematode prone ecology. These varieties are 95/01864, 89/02665, 85/01864, 96/00480, 95/18937, 95/00902, BD10, 96/01524 and TDr608. More positive perspective can be achieved by crossing some clones of D. alata and these D. rotundata.