EN
This study evaluates the effects of the two gibberellin inhibitors (daminozide, prohexadione-calcium) on certain growth and anatomical characteristics of coriander (Coriandrum sativum L.). Both growth retardants were found effective in reducing stem elongation; that response varied with the concentration used. Prohexadione-Ca at 200 mg l-1 reduced height by 38%. Coriander fruits were heavier after the application of prohexadione-Ca, but this did not translate to increased fruit yield or fruit essential oil yield. Prohexadione-Ca induced precocious anthesis (3-5 days earlier). Both prohexadione-Ca and daminozide apparently affected leaf and stem anatomy. Generally, retardant-treated plants possessed thicker leaves, wider stems with more collenchyma tissue, and more vessels in the vascular bundles. Chlorophyll fluorescence measurements disclosed a decrease in the photochemical efficiency of PSII in retardant-treated plants as compared to the controls. The chlorophyll fluorescence parameters Fv/Fm and Fv/Fo can provide a tool for early diagnosis of the use of growth retardant even before any signs of growth retardation are visible in the plants.