A COMPARISON STUDY ON STEM ELONGATION OF SEVERAL GREENHOUSE PLANTS

Stem elongation of young plants of Capsicum annum L., Dendranthema grandiflora Ramat., Euphorbia pulcherrima Wild and Klotsch, Pelargonium X hortorum L.H. Bailey, Petunia X hybrida and Salvia splendens was continuously measured under long-day (LD) and short-day (SD) conditions with a high degree of resolution, using linear voltage differential transducers under greenhouse conditions. A high stem elongation rate (SER) during the scotoperiod and a low SER during the photoperiod was found in Capsicum, Dendranthema and Salvia, In Euphorbia and Pelargonium the SER did not show large differences between photo- and scotoperiod while in Petunia the SER was largest during the photoperiod. There was no distinct difference in the elongation pattern under LD compared with SD conditions, nor a particular elongation pattern which could be connected to the photoperiodic requirement of the plants.