Early production of dry matter and itsrelationship to grain yield in maize (Zea mays L.)populations

The objectives of the research work were to determine whether early production of dry matter can be considered as a selection criterion, and to analyze the association of the traits in dissimilar environments with grain yield. The genetic material consisted of nine maize populations adapted to the environmental conditions of the southeast of the Coahuila state in Mexico, and the direct crosses between them. The genotypes were evaluated for the root dry weight (RDW) and stem dry weight (SDW) under laboratory and greenhouse trials, with and without stress due to salinity, and in the field, for grain yield. There was no evidence of a significant relationship between dry weight (RDW and SDW) in laboratory trials with the grain yield whereas, in greenhouse trials, a positive RDW and SDW relationship with stress and non-stress was found with grain yield, where the RDW (stress) showed a correlation of r = 0.308*. Results showed that there is genetic variation among populations for the evaluated traits, which is manifested in their expression, and in the potential of genetic combination of the crosses. Populations 6R and 7R were identified, and a significant group of crosses showing the combinations of them with positive values of grain yield and root and stem dry weight under salinity stress. Root dry weight (RDW) determined under salinity stress, jointly with RDW and SDW under non-stress conditions in the greenhouse can be considered as potential indicator for early selection of maize genotypes. Keywords: Zea mays L., salinity stress, environmental effects, native populations