Environmental factors affecting flowering of rice flower (Ozothamnus diosmifolius, Vent.)

Rice flower (Ozorhamnus diosmifolius, Vent.), native to east Australia, is a spring flowering perennial shrub. It is a new cut flower plant, recently introduced into cultivation in Australia and in Israel. Its response to env ironmental conditions, which affect growth and flowering, are not yet known . The purpose of the present study was to evaluate the effects of growth te mperature, photoperiod and total solar energy on flowering. Experiments wer e conducted with plants of the cv. Cook's Snow White. Plants were grown in three cycles under controlled conditions in the phytotron, at four day/nigh t temperature regimes: 17/9, 20/12, 23/15 and 26/18 degreesC. Two photoperi ods - short day (SD) of 10 h natural day light and long day (LD) of 10 h na tural light plus 10 h incandescent light - were employed. High temperatures enhanced vegetative growth but blocked flowering under both LD and SD. Und er medium-moderate temperatures plants were absolute LD plants and did not flower under SD conditions. Under lower temperatures plants flowered under both LD and SD, but SD delayed flowering. High total solar radiation under LD did not affect flowering time but greatly promoted the number of floweri ng stems. (C) 2001 Elsevier Science B.V. All rights reserved.