ICRISAT Archival Report 2006 - The seedlings of success in the ...

Activity 3B6.1: Screening groundnut breeding populations for multiple resistances
Milestone: About 700 F2-F7 breeding populations and lines with enhanced resistance to groundnut rosette disease
and aphids screened for resistance to early and late leaf spots at Samanko, Mali (2006)
Groundnut rosette is the most destructive disease of groundnut in sub-Saharan Africa. Improved rosette resistant
varieties of short-, medium- and long-duration have been developed but many are highly susceptible to the most
important foliar diseases (early and late leaf spots and rust). The resistant genotypes will form a strong component
of overall integrated disease management strategies along with cultural and biological management options. A total
of 844 diverse breeding populations and advanced breeding lines were screened for early leaf spot, the most
prevalent disease at Samanko (Table 8). Segregating populations were grown essentially for generation advance
and further selection.
Table 8. Breeding populations and lines screened for early leaf spot (ELS), Samanko , 2006
Objective Generation No. entries Source Number resistant
to ELS (score ≤ 5)
Rosette resistance and earliness F3 70 WCA 14
Rosette resistance and earliness F4 64 WCA 9
Aphid resistance and confectionery F4 55 ESA 8
(Virginia)
Aphid resistance x ELS resistance F4 124 ESA 23
Aphid resistance x rosette virus F5 33 ESA 0
resistance
GRV resistance F6 36 ESA 5
GRV and dormancy F6 63 ESA 4
Aphid and GRV resistance F6 49 ESA 0
Aphid resistance inheritance F6 27 ESA 1
Aphid resistance backcrosses F6 8 ESA 0
GRV inheritance- aphid x GRV F6 5 ESA 0
Dormancy and rosette resistance F6 27 ESA 0
Aphid and ELS resistance F6 16 ESA 1
Aphid and ELS resistance F7 92 ESA 7
Rosette resistance F7 5 ESA 0
High oleic acid and rosette resistance F7 21 ESA 0
Aphid and rust resistance F7 22 ESA 1
Aphid inheritance F7 127 ESA 2
Total 844
Generation advance: We grew 70 F3 and 63 F4 bulk populations at Samanko for generation advance. These
populations are derived from crosses involving early maturing susceptible lines and sources of resistance to
groundnut rosette disease. The aim of screening these for early leaf spots is to eliminate the super susceptible ones.
Among the F3 populations 14 recorded a score of ≤ 5 (on a scale of 1-9, where 1 is resistant and 9 highly
susceptible) while 9 of the F4 populations were rated as resistant. The most susceptible population had a score of ≥
7. Single pod bulks were made from the most productive plants with tolerance to ELS. These will be tested in rosette
disease nursery at Samaru, Nigeria at an appropriate time.
Evaluation of diverse breeding lines for early leaf spot: Breeding lines derived from various population for
incorporating resistance to both Groundnut Rosette Virus and aphid into different backgrounds were grown for
seed increase and screened for early leaf spot. Selected lines based on pod load will be evaluated for yield
and other desirable traits in initial variety trials in the 2007 crop season.
Advanced breeding nursery: At the request of the groundnut breeder at the Savanna Agricultural Research
Institute, Tamale Ghana, an observation nursery consisting of 12 rosette resistant early maturing (90 days) lines
were dispatched. Breeder seed of these lines was produced at Samanko.
BR Ntare and AT Diallo
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