résistance à la mosaïque virale de manihot glaziovii par greffage sur m. esculenta

Resistance to Mosaic Disease of M. glaviozii by Grafting on M. Esculenta. African cassava mosaic virus (ACMV) is an epidemic disease that causes great yield losses (> 50%). The grafting in the field of M. glaziovii on 3 cultivars of M. esculenta (Alot- Bikon, IITA 8034 and IITA 8061), permitted to evaluate the number of leaves per plant and the evolution of ACMV four times at one month intervals starting from 30 days after planting and the tuber yield, which was determined after 11 months. Crown grafting was realised 100 days after cuttings were planted. Controls consisted of ungrafted plants of each cultivar. After four months development, average number of leaves on the scion and controls varied from 41.3-50.0 and 24.2-45.3 leaves per plant respectively, showing a significant difference (P< 0.05) between grafted plants and controls. ACMV severity (expressed as %: cf. Material and methods) on controls was 54.3 ± 1.4, 51.6 ± 1.4 and 24.1 ± 0.9%, respectively for Alot-Bikon, IITA 8034 and IITA 8061. Meanwhile on grafted treatments, the severity was 9.4 ± 0.6; 7.8 ± 0.6 and 3.1 ± 0.6%, respectively. The use of M. glaziovii as scion led to about 85% reduction of viral infection. Grafted plants yielded fresh tubers varying from 23.9 ± 1.1 to 51.0 ± 0.9 t/ha contrary to controls for which 16.6 ± 1.1 to 38.1 ± 1.1 t/ha were recorded. The yield of grafted plants significantly increased (Fcal> Flu) by 11.0 t/ha (about 40%), compared to controls.