Type II callus production and plant regeneration in tropical maize genotypes.

A total of 113 maize inbreds adapted to tropical conditions were evaluated for their tissue culture response. Additionally, four media combinations of 15 or 30 µM dicamba with or without 88 µM AgNO3 were used to study the effect of dicamba and AgNO3 on type II callus production and plant regeneration from 42 of the inbred lines. Inbreds 48, 389 and 1345 of the populations BR 105, BR 112, and Catete, respectively, showed a high capacity for type II callus production and plant regeneration. The production of type II calli increased significantly when the concentration of dicamba was changed from 15 to 30 µM and when AgNO3 was added to the medium. A synergistic effect between 88 µM AgNO3 and 30 µM dicamba (CM-30Ag medium) was observed, leading to additional production of type II callus. Medium CM-30Ag allowed the best tissue culture performance and plant regeneration capacity.