POLLEN EFFECTS OF SELECTION IN MAIZE FOR THE REACTION TO ABSCISIC-ACID APPLIED TO SILKS

The objective of the research was to evaluate the effects on pollen of a selection conducted in maize (Zed mays L.) for the reaction to absc isic acid (ABA) applied to silks. Two single crosses were used as sour ces. Selected populations were developed by sib-pollinating ears treat ed with ABA (10(-3) M), while non-selected populations were obtained b y sib-pollinating untreated ears. The analysis of ABA concentration of the treated silks indicated that the selective agent was in part able to enter the silks and to move inward. The pollen performances of sel ected and non-selected populations were then compared for evaluating t he selection responses. Selected populations were superior for the pol len reaction in vivo evaluated as number of kernels earl obtained by p ollinating silks of the parental F(1)s sprayed with ABA. Selected popu lations were also superior for pollen tube length in vitro without ABA (i.e., for a trait reflecting the per se pollen vigour). In contrast, selected and non-selected populations did not significantly differ fo r the pollen reaction in vitro evaluated as grain germination and tube length in the presence of ABA. Results indicate that the selection pr ocedure was effective in improving both the pollen reaction in vivo to ABA applied to silks and the per se pollen vigour.