MULTIPLE-TRAIT IMPROVEMENT IN OHS3 USING A RANK AND REPLACE S(1) RECURRENT SELECTION METHOD

A recurrent selection program was conducted in OhS3, derived from BS3 synthetic. to develop maize germplasm with good agronomic traits (yiel d, standability early maturity, low grain moisture), resistance to vir us diseases, resistance to second-generation European corn borer (ECB- 2) (Ostrinia nubilalis, Hubner), and resistance to Northern Leaf Bligh t (NLB) of com [Exserohilum turcicum (Pass.) Leonard & Suggs]. Modifie d S1 recurrent selection based on a ''rank and replace'' selection met hod, the goal of which was to maintain and improve favorable allelic f requencies of the multiple traits, was used for five cycles to develop the OhS3(C5) synthetic maize population. The effectiveness of the ''r ank and replace'' selection method was evaluated by measuring performa nce in 60 S1 progenies representing each of the selection cycles 0-4 ( C0-C4). Shifts in the cycle population means for all traits were in th e desired direction and were highly significant for all traits except resistance to ECB-2 resistance to NLB. S1 progenies with superior rank ings for multiple traits occurred most frequently in cycle 4.