Evaluating Cassava Advanced Lines for Resistance to Cassava Mosaic and Brown Streak Diseases in Tanzania G. Mkamilo, H. P. Kulembeka, E.E Kanju, G. Matondo, C. S. Jeremiah, E. Masumba, D. Oyena, I. Rwomushana and F. Opio

Presentation Outline Importance of cassava in Tanzania Major biotic constraints Objective of this study Breeding approach Main findings and a Way forward Acknowledgements

Importance of cassava in Tanzania Tanzania is 4th cassava producer in Africa Cassava is second in production volume after maize 3. Total root production is 7M tons 4. Over 75% of the total production is used for human food

Fig. Cassava production (MT) in each zone in 2007/2008

Major Biotic constraints Cassava Mosaic Disease (CMD) Cassava Brown Streak Disease (CBSD) Cassava Green mites (CGM)

Cassava Mosaic Disease CMD is caused by single stranded DNA (ssDNA) of the Geminiviruses (CMGs) (family Geminiviridae; genus Begomovirus) Reported for the first time in 1894 (118 years) by Warburg Causing yield loss from 25 - 100% depending on variety

Cassava Brown Streak Disease CBSD is caused by a single stranded RNA (ssRNA) virus in the family of Potyviridae; genus Ipomovirus Reported for the first time in 1930s (82 years) by Storey in Tanzania Crop losses of up to 74% (Muhanna and Mtunda, 2002) reported in Tanzania

Table 1. Cassava productivity and production, and cropping area remain constant for 14 years

Management of cassava virus diseases The most realistic approach to reducing losses to Cassava Mosaic Disease (CMD) and Cassava Brown Streak Disease (CBSD) is the use of host-plant resistance or deployment of less-susceptible cultivars (Hillocks 2002).

Specific Objective To evaluate eleven cassava advanced lines for resistance to cassava mosaic and brown streak diseases in Tanzania

Breeding Approach Hybridization of CMD/CBSD resistant parents and farmer preferred varieties Screening 11 advanced lines for CMD and CBSD resistance between 2009 to 2011 at ARI Naliendele; a location with high CMD/CBSD pressure CMD and CBSD were assessed according to IITA (1990 ) and Hillocks et al (1996).

Research site Agricultural Research Institute (ARI) Naliendele in Mtwara, Tanzania

Evaluating cassava lines at ARI Naliendele in Mtwara, Tanzania

Breeding Approach Data on root yield and related traits were also collected at harvest. Data were subjected to analysis of variance and treatment means were separated using least significant difference test.

Table 2 Pedigree of advanced cassava lines evaluated in Tanzania 2009-2011 Clone Female parent Male parent Remarks KBH 2002/477 Kiroba Unknown Half sib KBH 2002/482 KBH 2002/494 KBH 96/1056 Uknown KBH 96/108 NR85200 Kigoma Red Landrace Naliendele Kibaha NDL 2003/031 Nanchinyaya Full Sib NDL 2003/111 Namikonga Kalulu NDL 2005/1471 NDL 2005/1472 NDL 2005/201 Namkonga Full sib NDL 2005/492

Main Findings There was significant differences for CMD, CBSD root necrosis and CBSD shoot infection among clones. Over 70% of advanced lines indicated field resistance against CBSD and CMD Significant differences were also revealed among clones for fresh root yield, number of roots per plant and harvest index Generally, four advanced lines out-yielded control check Kiroba

Table 3. Four outstanding cassava advanced lines Yield (t/ha) DM (%) 1. KBH 2002/482 23.4 28.9 2. KBH 96/1056 21.5 27.3 3. NDL 2003/111 24.2 27.5 4. NDL 2005/1471 23.9 29.0 5. KIROBA (Check) 18.6 27.3

A way forward Further evaluation of four superior cassava advanced lines at various agro-ecologies with involvement of farmers for official release and commercialization

Acknowledgement ASARECA for financial support IITA for technical backstopping Research Team for hard work

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