Identification of genomic regions associated with stay green in sorghum bytesting RILs in multiple environments

Stay green is an important drought resistance trait for sorghum production. QTLs for this trait with consistent effects across a set of environments w ould increase the efficiency of selection because of its relatively low her itability. One hundred and sixty recombinant inbreds, derived from a cross between QL39 and QL41, were used as a segregating population for genome map ping and stay green evaluation. Phenotypic data were collected in replicate d field trials from five sites and in three growing seasons, and analysed b y fitting appropriate models to account for spatial variability and to desc ribe the genotype by environment interaction. Interval mapping and non-para metric mapping identified three regions, each in a separate linkage group, associated with stay green in more than one trial, and two regions in singl e trial. The regions on linkage groups B and I were both consistently ident ified from three trials. The multiple environment testing was very helpful for correctly identifying QTLs associated with the trait. The utilisation o f molecular markers for stay green in sorghum breeding is also discussed.