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Growth Chamber Illumination and Photomorphogenetic Efficacy I. Physiological action of infrared radiation beyond 750 nm
Author(s) -
DEUTCH BENTE,
RASMUSSEN OLE
Publication year - 1974
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1974.tb04993.x
Subject(s) - infrared , fluorescence , incandescent light bulb , irradiation , radiation , visible spectrum , radiant energy , elongation , biology , horticulture , botany , materials science , optoelectronics , optics , physics , nuclear physics , metallurgy , ultimate tensile strength
Plants cultivated in growth chambers under such artificial illumination as fluorescent tubes show certain characteristic differences from plants grown in nature or under incandescent lamps. The plants grown under fluorescent light are shorter and more darkly pigmented; they also show different daylength requirements for certain photoperiodic responses. It was assumed that these effects were caused by the relative deficiency of far red irradiation (λ= 700–750 nm) in the emission from the fluorescent lamps. This assumption was tested on such light sensitive phenomena as stem elongation, flowering, the formation of resting organs, chlorophyll synthesis, and production yield in several plant genera. In all cases the plants were grown under long days (16 h). Six common types of growth chamber illumination were tested for their efficacy for long‐day induction. The spectral energy distribution of the lamps was measured. The emission from the various lamp types showed only small differences within the region of visible light (λ: 400–750 nm), but much larger diversity in the ratio of visible to infrared radiation (λ: 750–1000 nm). A strong correlation exists between the relative emission of infrared radiation and the photomorphogenetic efficacy of the lamps. Under fluorescent light the long‐day effect was weak or missing, but increased with increasing infrared emission. High infrared emission was also favourable for high production yield.