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ISHS Acta Horticulturae 435: II Workshop on Environmental Regulation of Plant Morphogenesis

INTENSIFIED PHOTOSYNTHETICALLY ACTIVE RADIATION AFFECTS THE RATES OF THREE PHYSIOLOGICAL DEVELOPMENT PHASES IN SINGLE-STEM ROSE PLANTS RAISED FROM SINGLE-NODE CUTTINGS

Author:   N. Bredmose
Keywords:   blind shoots, bud and shoot growth, cut rose, flowering, growth period, light quantum integral, plant population density, Rosa hybrida L., supplementary light
DOI:   10.17660/ActaHortic.1997.435.19
Abstract:
It has been suggested that light mainly affects the development time of roses from the onset of bud growth until the flower bud becomes visible. The effects of increased photosynthetic photon flux density on the duration of three physiological development phases from excision/planting of single-node cuttings till anthesis of single-stemmed rose plants were studied. Cuttings/plants of cut rose cultivars 'Kordapa' Lambada®, 'Tanettahn' Manhattan Blue®, 'Tanorelav' Red Velvet® and 'Sweet Promise' Sonia® were grown in long photoperiods at high air temperature and high plant densities in rockwool-cubes on ebb-flow units, irrigated with a complete nutrient solution and supplied with carbon dioxide to a level of 1000 μl l-1.

Plant development time was significantly reduced by an increase in daily light quantum integral from 17.8 to 21.0 mol m-2 day-1 in all three development phases, from excision/planting to onset of bud growth, from onset of bud growth to visibility of flower bud, and from visibility of flower bud to anthesis. The effects, however, were more distinct after the onset of bud growth, i.e. during the second and third phases, for which the reduction in days was about 25% greater than for phase one.

While the four cultivars reacted similarly, variation in plant population density modified the effects of increased quantum integral, resulting in clearer effects at the lower plant density of 100 plants m-2.

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