A breeding scheme for local adoption of cassava (Manihot esculenta Crantz)

Abstract

In many rural communities, cassava mosaic disease (CMD) resistant varieties are being rejected by farmers owing to their inferior root qualities when compared to locally adapted varieties. In response to this challenge, we implemented a breeding scheme whose objective was to combine CMD resistance with farmer preferred root qualities, whose genes were respectively sourced for elite and local varieties. We targeted to achieve this goal within five years that comprised of: i) hybridization of complementary parental lines, ii) seedling evaluation trial (SET); iii) clonal evaluation trial (CET); iv) modified preliminary yield trial (MPYT) and v) modified uniform yield trial (MUYT). At SET and CET, emphasis was placed on traits of moderate to high heritability while for MPYT and MUYT emphasis was on traits of low heritability. Generated F 1 progeny (4080 half sibs) were established in SET of which 1014 seedlings were selected and advanced to the CET. At CET, only 143 clones were selected and advanced. Under MPYT, slightly less than 50% of the clones were selected, while under MUYT, (8 to 40 clones per site) were selected. Clones selected per site were characterized by: DMC (28 to 38%); ii) HI (0.26 to 0.62); iii) yield (14 to 59 t/ha), resistance to CMD and desirable farmer root qualities. Given this outcome, we have demonstrated the utility of this scheme in accelerating development of locally adapted cassava varieties and thus propose the scheme be referred to as "speed cassava breeding"