Plant Growth Retardant and Initial Plant Height Affect Canna Lily Growth and Flowering

A study conducted in 2000 determined effects of two rates of Cutless and B-Nine/Cycocel tank mix and initial plant height on vegetative growth and flowering of Canna x generalis ‘Florence Vaughan’. Canna lily responded independently to plant growth retardant (PGR) treatment and initial plant height. Cutless suppressed vegetative height consistently up to 34% at the lower rate (25 ppm) and up to 41% at the higher rate (50 ppm) throughout the study, regardless of initial plant height. At first and second flower, increasing rates of Cutless suppressed vegetative height about 36% and 35–40%, respectively, and first and second flowering heights, 39–52% and 36–47%, respectively, with minimal effect on time to flower. Height suppression from B-Nine/Cycocel treatments was less than from Cutless with the greatest suppression, 12%, occurring at first flower. Differences in vegetative height among short, intermediate, and tall plants were most significant at treatment, decreased thereafter, and were not present 60 days after treatment (DAT). The number of days to first and second flower was affected by initial plant height with shorter plants flowering 10 to 15 days later than taller plants. At first flower, vegetative height of the initially tall plants was greatest, followed in succession by plants intermediate and short at treatment. However, by second flower, vegetative heights of plants, which were initially short and intermediate in height, were greatest, followed by tall plants. At first flower, flowering heights of all plants were similar and at second flower, flowering heights of the initially tall plants were slightly less [5–6 cm (1.9–2.3 in)] than those of intermediate and short plants.