Porat, R., The Kennedy-Leigh Centre for Horticultural Research, Faculty of Agriculture, The Hebrew University of Jerusalem, PO Box 12, Rehovot 76-100, Israel
Shlomo, E., The Kennedy-Leigh Centre for Horticultural Research, Faculty of Agriculture, The Hebrew University of Jerusalem, PO Box 12, Rehovot 76-100, Israel
Halevy, A.H., The Kennedy-Leigh Centre for Horticultural Research, Faculty of Agriculture, The Hebrew University of Jerusalem, PO Box 12, Rehovot 76-100, Israel

Celosia plumosa is a quantitative short-day plant in which a long photoperiod of 16 h markedly delayed flowering. Increasing the temperature regime from 17/12 °C to 27/22 °C (day/night) enhanced plant growth and flower stem and inflorescence length, and shortened the time to flower appearance. Pinching the seedlings increased the number of flower stems per plant, but under continuous short-day conditions their growth was retarded. Pinching the seedlings and maintaining them first for 3 weeks under non-inductive long-days to increase their vegetative growth, and then exposing them to inductive short days, increased the number of marketable flowering stems of suitable length. This suggested procedure of pinching followed by a long-day/short-day photoperiod also resulted in desirable inflorescence length with inflorescences born on stems of sufficient diameter and strength to significantly improve flower quality. © 1995.