THE EFFECT OF ROOT TEMPERATURE ON GROWTH, FLOWERING, AND VASE LIFE OFGREENHOUSE ROSES GROWN AT DIFFERENT AIR TEMPERATURES AND CO2 CONCENTRATIONS

The effect of root temperature (12, 15, 18, and 22 degrees C RT) on gr owth, flowering, and vase life of young rose plants (cv. Jaguar) was s tudied at two air temperatures (18 and 22 degrees C AT) or at two CO2 concentrations (360 and 850 mu mol mol(-1) CO2) at 22 degrees C. The e xperiment was carried out in growth chambers placed in a green-house a nd supplementary lighting at a photon flux density of 175 mu mol m(-2) s(-1) was given 20 h day(-1). A decrease in RT significantly decrease d number of flowering shoots, shoot fresh weight, and stem length irre spective of AT and CO2 concentration. The vase life of the roses was i ncreased when RT decreased or AT increased, while the CO2 concentratio n had no effect.