Effects of temperature on the development of Sinapis alba L. phytochrome-control of nitrate reductase activity at 10°C

Authors

  • S. M. MOROZ,

    Corresponding author
    1. Department of Botany, Plant Science Laboratories, University of Reading, Whiteknights, Reading RG6 2AS, Berkshire, U.K.
      *To whom correspondence should be addressed.
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  • E. A. ALFORD,

    1. Department of Botany, Plant Science Laboratories, University of Reading, Whiteknights, Reading RG6 2AS, Berkshire, U.K.
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  • C. B. JOHNSON

    1. Department of Botany, Plant Science Laboratories, University of Reading, Whiteknights, Reading RG6 2AS, Berkshire, U.K.
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*To whom correspondence should be addressed.

Abstract

Abstract. An analysis of three biochemical parameters during growth of white mustard in continuous white light (WL) has been undertaken at 10°, 15° and 20°C. The time required for anthocyanin and chlorophyll content and nitrate reductase [E.C. 1661 NAD(P)H: nitrate oxidoreductase] activity (NRA) to reach a peak in the cotyledons is shown to be temperature dependent, the rise in chlorophyll content being delayed to a much greater extent than anthocyanin content. In addition, with NRA, there is a significant increase in the level of the peaks with a lowering of temperature.

The NRA in dark-grown plants has been investigated in detail at 10°C. The pre-competence time for this response is increased to 20–24 h, compared with 14 h in seeds grown at 25°C. Other responses are affected far more by the lower temperature; for example, time for 50% loss of photoreversibility of a red (R) pulse in 48-h-old seeds is approximately 13 h, compared with 8 min in seeds grown at 25°C. At 25°C, light treatments during precompetence have been found to increase significantly the effectiveness of a subsequent R pulse on NRA; at 10°C, this effect appears to be almost entirely absent.

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