GENETIC-ANALYSIS OF ROOT TRAITS IN MAIZE

In many areas around the world, maize (Zea Mays L.) crops are affected by root lodging. Several authors have previously shown that associati ons of root and shoot traits enabled the prediction of the resistance of genotypes to root lodging. In this preliminary attempt to understan d the genetics of these traits, a set of 100 recombinant inbred lines from a cross between elite lines 'F2' (early, susceptible to root lodg ing) and 'Io' (late, lodging resistant) was considered. This populatio n was characterised for 152 RFLP loci and root system traits in one lo cation and for 2 years. QTLs were mapped using the average over years. Genetic and environmental correlations, together with co-localisation of QTLs for several traits, revealed genetic linkages, and some proba ble pleiotropic effects, which could be interpreted in terms of within -plant growth competition phenomena. The identification, on chromosome 5, of groups of loci involved in the control of the growth of the roo t system could help select against root lodging. ((C) Inra/Elsevier, P aris.).