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Subject Keyword BASIC BIOLOGICAL SCIENCES ♦ PLANTS ♦ SENSITIVITY ♦ RESPIRATION ♦ VEGETATIVE PROPAGATION ♦ VISIBLE RADIATION ♦ BIOLOGICAL EFFECTS ♦ AMMONIUM COMPOUNDS ♦ BIOASSAY ♦ BOTANY ♦ CLONING ♦ DAILY VARIATIONS ♦ ENZYME ACTIVITY ♦ FLOWERS ♦ METABOLISM ♦ NITRATES ♦ NITROGEN ♦ NUTRITION ♦ PHOTOPERIOD ♦ PHOTOSYNTHESIS ♦ PHYTOCHROMES ♦ PLANT GROWTH ♦ TIME DEPENDENCE ♦ BIOLOGY ♦ CHEMICAL REACTIONS ♦ ELECTROMAGNETIC RADIATION ♦ ELEMENTS ♦ GROWTH ♦ NITROGEN COMPOUNDS ♦ NONMETALS ♦ OXYGEN COMPOUNDS ♦ PHOTOCHEMICAL REACTIONS ♦ PIGMENTS ♦ RADIATIONS ♦ SYNTHESIS ♦ VARIATIONS 550500* -- Metabolism
Abstract In previous work with strain 6746 of Lemna paucicostata Hegelm. in heterotrophic culture, changes in the light schedule affected certain features of the daily respiratory pattern, on some but not all nitrogen sources, in a manner paralleling their effects on timing in the photoperiodic flowering response. Seeking further guidance on which metabolic processes should be investigated to understand this relationship, twelve additional strains were compared with 6746 in regard to (1) heterotrophic flowering under short-day skeleton photoperiods, and (2) daily respiratory patterns under 0.25 hr daily of dim red light. Heterotrophic flowering occurred in eight strains; among these, several differed sharply from 6746 in the character of their respiratory patterns and the probable relation of those patterns to photoperiodic timing. For example, in 6746, the second daily peak on NO/sub 3/, NH/sub 4/ and probably on glutamine reflects photoperiodic timing; the patterns on N-deficient, aspartate and glutamate media do not. In strains 6609 and 381, in contrast, glutamate also elicits a second peak probably reflective of photoperiodic timing; in strain 421, neither the NO/sub 3/ nor NH/sub 4/ patterns resemble those reflecting photoperiodic timing in 6746. Other strain differences in flowering, respiratory patterns and heterotrophic growth provide useful material for studying phytochrome action, N assimilation and respiration, and they confirm the view that strain identity may be crucial in biochemical investigations on Lemnaceae. These results also reinforce the concept that the temporal compartmentation of systems entrained to light/dark cycles can provide important insights, and should be more widely used, in work on regulation of plant metabolism.
Educational Use Research
Learning Resource Type Article
Publisher Date 1979-01-01
Publisher Place United States
Journal Am. J. Bot.
Volume Number 66
Issue Number 9
Organization Brookhaven National Lab., Upton, NY


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