Effects of different photoperiods on flowering time of qualitative long day ornamental annuals

Present study was carried out at the agricultural research institute,dera ismail khan,pakistan,during the year 2005. seeds of five qualitative ldps (pot marigold cv. resina,annual phlox cv. astoria magenta,cornflower cv. florence blue,oriental poppy cv. burning heart,flax cv. scarlet flax) were sown on 1st march 2005. the experiment was designed to study flowering response under four distinct controlled photoperiods (11,13,15 and 17 h.d-1). a curvilinear qualitative response was observed in almost all cultivars studied. pot marigold,annual phlox,cornflower,oriental poppy and flax took minimum time to flower when grown under 17 h.d-1 photoperiods however it was significantly (p<0.05) increased when photoperiod decreased to 11 h.d-1.