XVI International Botanical Congess

Research on poinsettia (Euphorbia pulcherrima) as a floricultural crop has shown that nitrogen applications can be significantly reduced when sufficient sulfur is present. Visually N and S deficiency symptoms can be somewhat similar and therefore confusing. In this study we examined the effect of varying levels of N and S on the morphology and anatomy of poinsettia. Vegetative and flowering experiments were run simultaneously using 'Freedom Red' poinsettia. Plants were fertilized using 4 levels of N and 3 levels of S. N deficiency, S deficiency and N and S interaction affected leaf size and color, plant size, stem color, and stem architecture. Anatomically, a notable difference in leaves was apparent in the 50 mg/L N treatment: the length of palisade cells was nonuniform from one cell to the next.