This thesis is an investigation of barrenness and plant-to-plant variability (PPV) in ear development of maize (Zea mays L.). A three-year field experiment was conducted on homogenous plants with similar initial plant size, development and uniform spatial patterns in parental inbred lines CG60, CG102 and their F1 hybrid CG60 × CG102. Physiological processes underlying barrenness were dissected into plant growth through development and dry matter partitioning to the ear at canopy, subpopulation, and primarily, individual plant levels. The growth and development of the ultimately barren individuals were followed from early vegetative stage to physiological maturity (PM) using a non-destructive allometric methodology. Plant-to-plant variability in ear development, related to plant development, was measured destructively from ear initiation to 1 wk after silking and at PM. Results showed that the individual plants exhibited differential responses to their previous growth and development in the two parental inbred lines. No physiological traits in growth and development or dry matter partitioning to the ear during the critical period bracketing silking could characterize individual barren plants. The F1 hybrid was resistant to barrenness even at 160,000 plants ha-1. At 80,000 plants ha-1, the spikelet number per row (SNPR) and spikelet number per ear (SNPE) exhibited less PPV around silking than earlier stages of development. For the three genotypes, PPV in plant morphological traits and ear length was relatively constant throughout development. In addition, the period around the kernel row number (KRN) formation stage was the only time-window that the PPV in stem volume, representing PPV in above-ground plant dry matter (PDM), affected PPV in SNPR and KRN for the three genotypes, with SNPR being more affected. Although the F1 produced greater PDM at silking and 1 wk after silking, it had shorter ear length and less ear dry matter than the two parental inbred lines at the corresponding stages. When the relationships are elucidated among early ear development, plant growth, leaftip development, and dry matter partitioning to the ear, during the vegetative to silking stages and under stress conditions, then the physiological processes underlying barrenness of the tested inbred lines could be further characterized. / Syngenta, the Ontario Research Fund, the Ontario Ministry of Agriculture, Food and Rural Affairs, and the Natural Sciences and Engineering Research Council of Canada