EFFECTS OF DIFFERENT SOWING DATES (AMBIENT DAY LENGTH) ON FLOWERING TIME OF IMPORTANT ORNAMENTAL ANNUALS

Abstract

Present study was carried out at Agricultural Research Institute, D. I. Khan, Pakistan, during the year 2004-2005. Seeds of six SDPs (Zinnia cv. Lilliput, Sunflower cv. Elf, French Marigold cv. Orange Gate, African Marigold cv. Crush, Cockscomb cv. Bombay and Cosmos cv. Sonata Pink) and ten LDPs (Moss Rose cv. Sundance, Pansy cv. Baby Bingo, Snapdragon cv. Coronette, Petunia cv. Dreams, Pot Marigold cv. Resina, Annual Phlox cv. Astoria Magenta, Cornflower cv. Florence Blue, Oriental Poppy cv. Burning Heart, Flax cv. Scarlet Flax and Annual Verbena cv. Obsession,) were sown at 15 days interval in their responsive growing season i.e. SDPs from September to January (short day length) and LDPs from March to July (long day length). SDPs were raised from 1st September to 15th December and LDPs from 1st March to 15th June showed a non-significant (P<0.05) difference in days taken to flowering. However, a significant (P<0.05) difference was observed when late sowing dates (1st and 15th January in SDPs and 1st and 15th July in LDPs) were compared with the rest. It is therefore concluded that very late sowing in either case significantly delayed flowering time because SDPs of late sowing dates (1st and 15th January) received long days and more light integrals at flower development stage hence increased flowering time. Similarly, LDPs raised from 1st to 15th July received short day length and less light integrals at floral development stage which enhanced flowering time.