Flowering response of facultative short day ornamental annuals to artificial light intensities

Seeds of 6 facultative sdps (zinnia cv. lilliput,sunflower cv. elf,french marigold cv. orange gate,african marigold cv. crush,cockscomb cv. bombay and cosmos cv. sonata pink) were sown into module trays containing homogeneous leaf mould compost. after germination,saplings of each cultivar were shifted into four light intensity chambers (42,45,92 and 119μmol.m-2.s-1) for a duration of 8h (from 08:00 to 16:00h) to observe their flowering response. the findings of this study showed that facultative sdps raised under low irradiance (42 and 45μmol.m-2.s-1) were more responsive to produce early flowers. however,there was a non-significant difference between 42 and 45μmol.m-2.s-1 and 92 and 119μmol.m-2.s-1 irradiance levels. although facultative sdps under 42μmol.m-2.s-1 flowered few days earlier than those received 45μmol.m-2.s-1 irradiance but the quality of plants (plant height and leaf appearance) was inferior. it is therefore concluded that for better plant quality and early flowering facultative sdps should be grown under 45μmol.m-2.s-1 irradiance. moreover,these plants can be kept under high light intensity (92μmol.m-2.s-1) to prolong juvenile phase for continuous supply in the market.