Performance of maize triple cross-way hybrids in three environments in São Paulo State, Brazil

The objectives of this investigation were to study the combining ability of 30 lines of the maize breeding program of the Instituto Agronomico, São Paulo State, Brazil, in top crosses squemes, aiming at to identify lines for developing high yield triple cross hybrids with two testers (single cross hybrids). The 60 top crosses along with two checks were evaluated in 2001/2002, in two experiments, named TC1 and TC2, following a randomized complete block design with three replicates, over three locations: Campinas (Centro Experimental Central), Mococa (Pólo Regional de Desenvolvimento do Nordeste Paulista/APTA) e Palmital (Pólo Regional de Desenvolvimento do Vale do Paranapanema/APTA). The traits evaluated were: Plant height (AP) and ear height (AE), percentage of lodged and broken plants (Ac + Que), ear yield (PE) and grain yield corrected to 14% moisture (PG). The combining ability of the lines to PG was estimated according to Griffing's Method 2. The results showed that both effects CGC and CEC were important in the 2 x 30 diallel. The lines L 126, L 111, SLP 103 and IP 330 were outstanding as to the combining ability for PG in the three locations, being usefull for synthesis of base population in recurrent selection programs or for hybrid programs for broad adaptation. On the other hand, some lines showed high gi estimates in specific locations, such as L 3 and L 161 in Palmital; IP 4035 in Mococa, AL 326 and L 14 in Campinas. Thus, to maximize the hybrid yield potential for each location, the choice of lines must be made with CGC effects within each location.

combining ability; top cross; triple cross-way hybrids