Phenotypic Changes and Meiotic Abnormalities Induced by Plant Growth Regulators in Zea Mays L

The Maize is ranked the third cereal crop in the world after rice and wheat. Plant growth regulators (PGRs) are synthetic hormones that are effective or more than natural plant hormones. This study aimed to assess phenotypic changes and meiotic abnormalities induced in maize influenced by PGRs. Two single hybrid genotypes of maize, as well as, two PGRs including gibberellic acid (GA3) and ethephon were used in this study. Maize grains were soaked in two different concentrations of each PGR for 12 hours before sowing in the field. The experimental design was a randomized block design arranged in split-split plots with three replications per treatment. GA3 displayed a wide spectrum of meiotic anomalies in the H1 genotype, the most being stickiness, varied asynchronization, stray bivalent, multivalent and late movement of chromosomes toward the opposite poles. Meanwhile, meiotic anomalies induced by GA3 in the H2 genotype include stickiness, chromosome scattering and varied asynchronization. Ethephon induced meiotic abnormalities in the H1 genotype were related to laggards, stickiness, disorientation of bivalents, multivalent with non-oriented on the equatorial plate, disturbed polarity, chromosome scattering, cytoplasmic attachment and stray bivalent. Other aberrations induced by ethephon in the H2 genotype include non-oriented bivalents at metaphase I. The spectrum of meiotic aberrations was found higher in H1 than in H2 genotype, as well as, at metaphase than anaphase and telophase. These abnormalities can cause male sterility. This finding can open novel approaches in plant breeding programs of the species that are devoted to hybridization where manual cross-pollination is difficult and time-consuming.