Response to different adaptative mass selection criteria in maize exotic population

Limited information is available in maize (Zea mays L.) with respect to the application of different selection criteria to adapt exotic germplasm to a particular area. A comparison among different selection criteria could giv e important information For the efficiency of the selection process. The st udy was designed to compare the responses to different mass selection crite ria for adaptation applied over the same original population. Four cycles o f selection were completed for an exotic maize population. Selection was ba sed on six criteria, PEG (prolificacy, ear length, and grain length); RTO ( individual plant yield); PRE (early silk emergence); HI (harvest index); PE (prolificacy and ear length), and ASI (anthesis-silking interval). The ori ginal population and four cycles corresponding to each criterion were teste d For grain yield response during three consecutive years. Ten random famil ies derived from each four-selection criterion were evaluated For morpholog ical characters during two years. Grain yield increased significantly from C0 to C4 with the application of all selection criteria, with the exception of HI criterion. increases in grain yield expressed as average response, w ere 3,2% for PKE, ASI and RTO, 3,1% for PEG, and 2,8% for PE. The HI criter ion was not effective for adapting exotic germplasm. Mass selection based o n PRE, ASI, PE, PGE and RTO, were effective in developing populations with an agronomic performance similar to an adapted population check. Direct sel ection for yield (RTO) was as effective as indirect selection based in ear characteristics. The advantage of PRE and ASI criteria in comparison with t he other criteria applied during this study is that PRE and ASI are more si mple and accurate to measure a large number of germplasm introductions in f ield experiments.