Determination of Photoperiod-sensitive Stages of Development of the Short-day Plant Celosia

Abstract

Celosia argentea L. var. plumosa Voss. (celosia) is a bedding plant crop that often exhibits premature flowering during commercial production, resulting in plants of unacceptable quality. Celosia is a facultative short-day plant. Understanding the photoperiod-sensitive stages of development is critical for management of photoperiodic crops. Limited inductive photoperiod experiments, in which photoperiodic plants are moved from noninductive to inductive conditions for flowering at varying stages of development and for varying durations before returning to noninductive conditions, were conducted to determine when celosia becomes sensitive to floral-inducing short days and how many photoinductive cycles are necessary for floral induction. Plants became receptive to short days ≈9 to 12 days after seedling emergence (DAE). Between six and nine short photoperiods beginning 9 DAE were sufficient to commit plants to flowering, depending on the cultivar evaluated. Early flowering was highly correlated with reductions in plant quality parameters, including the number of inflorescences produced, the number of lateral branches, and shoot dry weight. By the time plants had developed five nodes, photoperiod no longer impacted time to flower, indicating that celosia remains photoperiod-sensitive for floral induction only from ≈9 to 45 DAE at 20 °C.