New CMD-resistant cassava varieties released in NigeriaA.G.O. Dixon, M. Akoroda, R.U. Okechukwu, P. Ilona, F. Ogbe, C. Egesi, G. Ssemakula, L. Sanni, J. Lemchi, C. Ezedinma, B. Maziya-Dixon, O. N. Eke-okoro, E. Okoro, A. A. Adeniji, G. Tarawali, and K. Nwosu.

Correct citation: IITA Integrated Cassava Project, 2007. New CMD-resistent cassava varieties released in Nigeria© Designed and printed at the International Institute of Tropical Agriculture Ibadan, Nigeria. Concept: R.U. Okechukwu Graphic Layout: C.O. Geteloma

INTRODUCTIONA severe form of cassava mosaic disease (CMD), started in Uganda in the mid-1990s, and spread to neighboring countries and beyond. The severe CMD is caused by a highly virulent Ugandan strain of East African cassava mosaic virus (EACMV-Ug2), an interspecific hybrid of African cassava mosaic virus (ACMV) and East African cassava mosaic virus (EACMV). When EACMV-Ug2 co-infects cassava with ACMV, the symptoms are very severe. The CMD pandemic in Uganda led to cassava being almost totally abandoned, resulting in food insecurity there in the late 1990s.

ACMV and EACMV, which recombined in Uganda to produce EACMV-Ug2, both exist in Nigeria and when they co-infect cassava, the plants also suffer very severe damage. Even if EACMV-Ug2 does not spread to Nigeria, varieties with a diverse genetic make up for resistance to CMD are needed to forestall any eventual evolution of a new, severe strain.

A strategy was adopted using a large pool of human resources. NARS, univer-sities, industry, government, farmers, and processors were to engage in activi-ties to lead to cultivar-substitution. The susceptible varieties on farmers’ fields would be replaced by superior genotypes that are not only CMD resistant or tolerant but also high yielding with a high dry matter content.

METHODSDuring the 2003/2004 and 2004/2005 seasons, on-farm trials (OFTs) and demon-stration trials (DEMOs) were conducted using a fast track participatory selection approach in 12 target States: Abia, Akwa Ibom, Anambra, Bayelsa, Cross River, Delta, Ebonyi, Edo, Enugu, Imo, Ondo, and Rivers. In addition, 18 multilocational trials (MLTs) (2003/2004), and 32 MLTs (2004/2005) were also conducted across the different agroecologies of Nigeria. The NRCRI during this period also con-ducted the National Coordinated Research Project (NCRP) on cassava. Over 40 new clones were evaluated along with three known checks (TMS 30572, TMS 4(2)1425, TMS 82/00058). Scientists conducted the MLTs. The farmers conduct-ed the OFTs and DEMOs with assistance from the various State Agricultural De-velopment Programs.

RESULTSThe varieties released after 2 years from IITA and NRCRI were TMS 98/0510, TMS 98/0581, TMS 97/2205, TMS 98/0505, TME 419, TMS 92/0326, TMS 96/1632, TMS 98/0002, TMS 92/0057, and NR87184 (Plates a–j).

From data analysis of 2500 trials (OFTs, DEMO, MLTs, and NCRP, across 2 years) these released varieties were found to have multiple resistance/tolerance to CMD and other major problems of cassava, bacterial blight disease, anthracnose, green mite, and mealybug. They are high yielding, suitable for use as food and livestock feed, also as a raw material in industry.

This poster shows the morphological characteristics to inform the public on how to identify these new, improved varieties. The ten varieties are now extensively multiplied for wide distribution to farmers to sustain cassava cultivation and pre-emptively manage the virulent Ugandan strain of EACMV.

Integrated Cassava Project, International Institute of Tropical Agriculture (IITA). Ibadan Office: PMB 5320, Ibadan, Nigeria Telephone: (+234 2) 241 2626 Fax: (+234 2) 241 2221International Mailing Address:IITA-Integrated Cassava Project C/o Lambourn (UK) LtdCarolyn House 26 Dingwall Road Croydon CR9 3EE, UK E-mail: iita-icp@cgiar.org Web: www.cassavabiz.org ; www.iita.org

Origin/Source of variety: International Institute of Tropical Agriculture (IITA), Oyo Road, Ibadan and National Root Crops Research Institute (NRCRI), Umudike Name of developing/introducing organization: IITA and NRCRI Adaptation: Widely adapted across the agroecologies from the humid forest in southern Nigeria to the savanna in the north Pest/disease tolerance: Cassava mosaic disease, bacterial blight disease, anthracnose disease, cassava mealybug, and cassava green miteOutstanding characteristics: Very suitable for mixed cropping, high yielding, suitable for food, industry, and livestock

a. General Descriptors Original name or Breeder’s code TME 419 TMS 97/2205 TMS 98/0505 TMS 98/0510 TMS 98/0581 TMS 92/0057 TMS 92/0326 TMS 96/1632 TMS 98/0002 NR 87184 Pedigree Gbasekoute OP TMS 30572 × TME 6 97 DTP REP 2 bulk 97 DTP REP 2 bulk MPR POP REP 1 bulk (TMS 30555 × TME 1) HS (TMS 91934 × TME 1) HS TMS 94/0325 × TME 7 97 DTP REP 1 83 DTP REP 1 Days to maturity (months) 12 12 12 12 12 12 10–12 12 10–12 10–12 Potential root yield (t/ha) 35.2 31.8 45.5 37.5 47.3 37.7t/ha 39.5t/ha 43.2t/ha 48.4t/ha 34.6t/hab. Specific Descriptors Plant type Tall (3–4 m) Moderate in height Moderate in height Moderate in height Tall (about 3 m) tall (2–3m) tall (2–3m) tall (about 3m) moderate in height (2m) tall (about 3m) (about 2 m) (about 2 m) (about 2.5 m) Branching habit Usually no branching Profuse branching Profuse Moderately profuse Moderately profuse branches moderately branches lightly branches sparsely branches profusely branches profusely Height of branching Not applicable Low (about 0.5 m) Low (about 0.5 m) Moderately high 0.5–1.0 m Low (1.0–1.3m) low (0.7–2.0m) high (about 1.5m) low (about 0.5m) low (0.1–1.1m) (about 1.2 m) Suitability for mixed cropping Very suitable Not suitable Not suitable Fairly suitable Fairly suitable fairly suitable Suitable fairly suitable not suitable not suitable Color of unexpanded young leaf Orange Purple Dark red Brown Purple Purple lime (yellowish green) Brown lime (yellowish green) dark yellow First fully expanded leaf color Green Plum (reddish purple) Lime (pale green) Lavender Green with taint of red Purple lime (yellowish green) lime (yellowish green) bright green bright green (verylightpurple) towardsthebaseoftheleaflets Pubescence of young leaf Absent Absent Little pubescence High pubescence High pubescence Absent present light Absent Absent Central leaf lobe shape Lanceolate Lanceolate Elliptic Lanceolate Elliptic Lanceolate elliptic Lanceolate Lanceolate Lanceolate Petiole color Green Green with taint of The base is lime Green Red Red Red red interspersed light green Green light orange towards which graduates into with green towards theleaflet orangetowardsthe thebase leaflets Young stem color Dark green Dark green Green Dark green Green with taint of red light green with red taint green with red taint light green light green Green Stem color Brown Brown Light yellow Brown Light yellow Brown light brown light brown Light yellow Brown Flower Absent Present Present Absent Absent Present Present Present Present Present Root neck length Short Intermidate Absent Short Short Short Short Short Short Short Outer root skin color Brown Brown Tan (yellowish brown) Brown Tan (yellowish brown) Brown Brown Light brown light orange Brown Inner root skin color White or cream White or cream White or cream White or cream White or cream Cream Light yellow light yellow White light yellow Pulp color White or cream White or cream White or cream White or cream White or cream White White Cream White White CNP (ppm) 110.1 95 77.4 109.9 114.7 155ppm 80.8ppm 230.5ppm 86.8ppm 89.8ppm Dry matter of fresh roots (%) 39 39 36.2 34 36 39.3 29.4 42.9 38.3 41.6 Gari yield (%) 23.5 18 22.5 26.3 22 29.6 21.3 24.4 22.9 25.9 Starchfromrootflour(%) 65.7 66.9 67.1 66.8 68.1 73.0 78.9 81.3 73.4 60.8 Sugar (%) 4.6 4.7 4.5 5 5.1 4.41 5.20 5.3 3.9 – Protein (%) 2.3 3.7 4 3.3 3.4 2.57 2.32 3.3 2.7 – Ash (%) 1.5 1.7 1.8 1.7 2.3 1.56 1.7 1.75 2.58 – Fibre (%) 1 1 1 1 1 1 1 1 1 – Amylose % of the starch 18.7 19 20.2 20.2 19.8 18.52 20.71 18.88 18.18 –

TMS 97/2205

e

TMS 98/0505

d

TMS 98/0510

c

TMS 98/0581

b

TME 419

a

TMS 98/0002

i

TMS 92/0326

h

TMS 92/0057

g

TMS 96/1632

i

TMS 30572

k

Newly released varieties in Nigeria

Commonly available old improved varieties in Nigeria

U M U D I K E

NATI

ON

AL R

OOT CROPS RESEARCH INSTITUTE

TMS 4(2)1425

l

TMS 82/00058

m

NR 8082

m

NR 87184

j