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  • Author or Editor: Brent Pemberton x
  • Journal of the American Society for Horticultural Science x
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Abstract

Florida-produced ‘Prize’ azalea plants were shipped to Minnesota with apical floral buds whose individual flowers had styles which had commenced elongating. These plants were ready for rapid forcing if given the traditional 6 weeks at 9°C. However, a single 2000 ppm GA (Pro Gibb3) spray treatment resulted in plants which flowered more rapidly without a traditional cold treatment when forced in a glasshouse under natural daylength (ND) in Minnesota during the spring and summer. Length of the ND in these experiments was considered critical, as plants forced in the spring and summer under an 8-hr short day (SD) treatment did not flower in a uniform manner, or floral abortion occurred in GA treated, uncooled plants forced during the autumn. Under ND conditions, extended to 20-hr by high pressure sodium, cool-white fluorescent or incandescent lamps, plants flowered more rapidly than those plants cooled at 9° for 6 weeks and forced under ND. Uniformity of flowering was enhanced and GA treatment had no effect when 3 weeks of 9° cooling preceded supplemental lighting treatments during autumn forcing. During winter, 20-hr of high pressure sodium + GA treatment or a SD treatment of noncooled plants resulted in more rapid, but similarly uniform flowering, when compared to plants with 6 weeks of cold treatment. These data provide evidence indicating that ‘Prize’ azalea floral buds may not exhibit a physiological dormancy.

Open Access

Abstract

Lily plants were exposed to natural daylight (ND), 50% ND (50% saran), ND plus 16 hours of incandescent (Inc) or ND plus 16 hours of high pressure sodium discharge (HID) lamp light at both University of Minnesota and Michigan State University. Light intensity had no significant horticultural effect on plant development rate that could not be readily explained by temperature. The Inc or HID light source hastened flowering by 5 to 8 days over the ND plants when given from emergence to flower. However, the rate of development from visible bud to flower was not influenced by light intensity. Plant heights were increased by all light treatments when compared to the ND plants. These increases appeared due to photoperiod for the HID treated plants, photoperiod and light quality for the Inc treated plants, and light quantity for the 50% saran-treated plants. The number of flower buds initiated was not affected by light treatment but Inc lighting increased flower bud abortion. Final plant height was highly correlated with height at visible bud; final height being about double the height at visible bud when plants were grown continuously under ND, HID, or 50% saran.

Open Access