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RESPONSES OF LIGHT-GROWN WILD-TYPE and LONG-HYPOCOTYL MUTANT CUCUMBER SEEDLINGS TO NATURAL and SIMULATED SHADE LIGHT

Authors

  • C. L. Ballare,

    Corresponding author
    1. Departamento de Ecologia, Facultad de Argronomia, Universidad de Buenos Aires, Av. San Martin 4453, 1417-Buenos Aires, Argentina
      †To whom correspondence should be addressed.
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  • J. J. Casal,

    Corresponding author
    1. Departamento de Ecologia, Facultad de Argronomia, Universidad de Buenos Aires, Av. San Martin 4453, 1417-Buenos Aires, Argentina
    2. †CLB and JJC contributed equally to this work. The order of these authors is arbitrary because they tossed up for it.
      †To whom correspondence should be addressed.
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  • R. E. Kendrick

    1. Department of Plant Physiological Research, Wageningen Agricultural University, Generaal Foulkesweg 72, NL-6703 BW Wageningen, The Netherlands
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  • *Dedicated to M. Furuya on the occasion of his 65th birthday.

†To whom correspondence should be addressed.

Abstract

The photomorphogenic control of hypocotyl extension growth was characterized in wild type (WT) and long hypocotyl (Ih) mutant seedlings of cucumber (Cucumis sativus L.) grown under natural radiation in outdoor and glasshouse experiments. Hypocotyl extension growth of WT plants was promoted by supplementing sunlight with far-red light during the photoperiod, by reducing the amount of blue light reaching either the whole shoot or the hypocotyl, and by reducing the amount of UV reaching the whole shoot.The Ih seedlings only responded to a reduction in UV-B levels. Both WT and Ih seedlings showed phototropic responses to the direction of blue light. Increasing degrees of vegetational shade promoted hypocotyl growth of WT plants. The Ih mutant showed no hypocotyl growth promotion by natural shade in glasshouse experiments (no UV-B, low water demand) and a reduced response (10-23% of the WT response, according to pretreatment conditions) in outdoor experiments (UV-B, high water demand).

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