Plant growth regulators ameliorate or exacerbate abiotic and biotic stress effects on Zea mays kernel weight in a genotype-specific manner

ABSTRACT Plant growth regulators have documented roles in plant responses to single stresses. In combined-stress environments, plants display novel genetic architecture for growth traits and the response to growth regulators is unclear. We investigated the role of plant growth regulators in combined-stress responses in Zea mays. Twelve maize inbreds were exposed to all combinations of the following stressors: drought, nitrogen, and density stress. Chemical treatments were utilized to alter balances of the hormones abscisic acid, gibberellic acid, and brassinosteroids. We found a significant difference between the seed weights of plants given different chemical treatments after accounting for differences in genotype and stress environments. We conclude that plant growth regulators have targets in combined-stress response pathways in Zea mays. HIGHLIGHT Plant growth regulators can ameliorate effects of combinations of abiotic and biotic stress in maize, in certain genotypes and under specific stress conditions.