DIVERGENT SELECTION FOR EAR LEAF AREA IN MAIZE

Eight cycles of divergent selection for ear leaf area in two maize (Zea mays L.) synthetics resulted in changes in total leaf area Objectives were to evaluate se- lection response using several experiments. Each cycle consisted of four strains two high and two low ear leaf area strains. Selection response for high ear leaf area, strains during eight cycles, increased ear leaf area 228 cm 2 for RBS20 and 162 cm 2 for RSSSC. Low ear leaf area strains decreased 245 cm 2 for RBS20 and 261 cm 2 for RSSSC. Three years of replicated trials of cycle 0, cycle 4 and cycle 8 for synthetics and their crosses showed signif- icant response to selection. Ear leaf area change cycle -1 for the high strains were b=+16.8* for RBS20, b=+17.3** cm 2 for RSSSC and high ear leaf area crosses b=+15.6** cm 2 . Decreases for low ear leaf area strains were b=-26.1 ** cm 2 for RBS20, RSSSC b=-24.5** cm 2 and crosses b=- 33.1** cm 2 . Divergent selection for ear leaf area changed leaf area above ear leaf and certain agronomic traits. Days to pollen-shed, harvest grain moisture and seed size all changed. Plant height, leaf number, grain oil, protein and starch concentration did not change. Results suggest both source and sink determine seed size and chemical com- position in maize grain.