Tanzania Agricultural Research Institute

Author(s) : Happy Daudi, Hussein Shimelis, Isack Mathew, Abhishek Rathore & Chris O. Ojiewo

Groundnut rust caused by Puccinia arachidis Speg. is a major cause of yield and quality losses in groundnut (Arachis hypogaea L.) in the warm-humid tropics including Tanzania. Breeding and deployment of rust resistant cultivars with farmer-preferred attributes will bolster groundnut production and productivity. The objective of this study was to determine the combining ability efects and gene action controlling rust resistance in groundnut genotypes for breeding. Twelve selected and complementary parental lines were crossed in a diallel design, to develop F1 progenies, which were advanced to the F2 for individual plant selection. Thirty-three successful partial crosses and the 12 parents were feld evaluated using a 5× 9 alpha lattice designs with two replications over two seasons in Tanzania. The tested genotypes exhibited signifcant (P< 0.05) variation for rust resistance, yield and yield-related traits. There existed signifcant (P< 0.05) diference on the general combining ability (GCA) efect of parents and the specifc combining ability (SCA) efect of progeny for the assessed traits indicating that both additive and non-additive gene efects conditioned trait inheritance. The Bakers’ ratios indicated that the non-additive gene efects predominantly controlling rust resistance and yield components. This suggested that transgressive segregants could be selected for improved rust resistance and yield gains in the advanced pure line generations. Genotypes ICGV-SM 05570 and ICGV-SM 15567 were the best general combiners for rust resistance and grain yield. The crosses ICGV-SM 16589 ×Narinut and ICGV-SM 15557 × ICGV-SM 15559 were identifed as the best specifc combiners for rust resistance with moderate yield levels and medium maturity. Genotypes with desirable GCA or SCA efects were selected for further breeding.