Effect of light colour on forced hyacinth

Three cultivars of Hyacinthus orientalis L. were forced under artificial light using fluorescent lamps emitting white, blue, green, yellow and red light. Quantum irradiance was determined as 12.5 and 25 μmol m-2 s-1. Day length was 12 and six hours, respectively. Daily light integral was 0.54 mol m-2. A significant effect of light colour on flowering date and plant quality was observed. Plants forced in blue and red light were the first to flower. Plants exposed to red light formed longer inflorescences. Plants forced under lamps emitting blue light formed shorter, more rigid flower shoots with shorter leaves. There were no significant differences between plants grown under 25 μmol m-2 s-1 of quantum irradiance for six hours per day and plants grown under light with a quantum irradiance of 12.5 μmol m-2 s-1 for 12 hours per day. This means that the light-dosing variant did not exert any effect on the growth and flowering of hyacinths.