GENETIC DIVERSITY FOR RFLPS IN EUROPEAN MAIZE INBREDS .1. RELATION TO PERFORMANCE OF FLINT X DENT CROSSES FOR FORAGE TRAITS

Restriction fragment length polymorphisms (RFLPs) have been proposed as a tool for assigning inbreds to heterotic groups and predicting heterosis and performance of single-cross hybrids in maize (Zea mays L.). Such use was evaluated in 11 flint and 11 dent inbred lines from the European maize germplasm and in 66 F1 hybrids produced between them according to an incomplete factorial mating scheme. Inbreds and hybrids were evaluated for 12 forage yield and quality traits in three and six environments, respectively, in Germany. The RFLP assays of the 22 inbreds were performed with two restriction enzymes and 101 DNA probes distributed throughout the maize genome. Most (> 97%) clone-enzyme combinations revealed polymorphisms (almost-equal-to 5.0 variants per clone-enzyme combination). Genetic distances (GD) between lines, calculated from RFLP data, had a significantly greater mean for flint x dent (0.65) than for flint x flint (0.58) or dent x dent (0.59) line combinations. Cluster analysis based on GDs revealed associations among lines consistent with their origin from different heterotic groups and known pedigrees. The GD values pertaining to the 66 F1 hybrids were partitioned into general (GGD) and specific (SGD) genetic distances; GGD explained almost-equal-to 30% of the variation among GD values. Neither GD nor SGD was significantly correlated (Absolute value of r less-than-or-equal-to 0.25) with F1 performance or midparent heterosis for any trait examined. Results from this study support previous investigations with U.S. maize germplasm in that RFLP data can be used for assigning inbreds into heterotic groups. However, RFLP-based genetic distance measures are apparently not indicative of the performance of single-cross hybrids between lines from different heterotic groups for forage traits.