This PhD project investigates the use of plant growth regulator (PGR) applications in assisting cotton plants become more efficient and resilient to abiotic stresses, and to deliver improvements in cotton yield and lint quality. It investigates relevant biochemical pathways of plant and crop responses to treatments, as well as agronomic responses. Because water availability drives production, abiotic stressors are a major limiting factor of yield and lint quality. In lower-yielding systems, PGRs enhance overall crop performance and yield, notably in water-deficit scenarios. In Australia, novel PGRs could be used to address water deficit, heat and cold stressors and soil abiotic constraints.