A comparison of low temperature growth vs low temperature shifts to induce resistance to photoinhibition in spinach (Spinacia oleracea) |
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Authors: | G R Gray S R Boese N P A Huner |
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Institution: | G. R. Gray and N. P. A. Huner (corresponding author). Dept of Plant Sciences, Univ. of Western Ontario, London, ON N6A 5B7, Canada;S. K. Boese. Boyce Thompson institute for Plant Research. Ithaca. NY 14853. USA. |
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Abstract: | Plants of Spinacia oleracea L. cv. Savoy grown under cold-hardening (5°C) and nonhardening (16°C) conditions were exposed to a photoinhibitory irradiance of 1300 μmol rrr: m-2 S-1 5°C for 12 h. Plants grown at 5°C exhibited a greater resistance to photoinhibition at low temperature in comparison to plants grown at 16°C as measured by the photochemical efficiency of photosyslem II. In contrast, tuily expanded leaves of plants grown at 16°C and then shifted to 5°C for 10 days did not exhibit increased resistance to photoinhibition. This was observed irrespective of the phoioperiod experienced during the shift to a lower temperature. Furthermore, spinach grown at 16°C and subsequently exposed to a stepped, daily decrease in temperature from 16 to 1°C over 10 days w ith a concomitant reduction in photoperiod. also did not exhibit any change in susceptibility to photoinhibition. Thus, a decrease in photoperiod accompanied by either an abrupt or stepped low temperature shift cannot induce increased resistance to photoinhibition. This confirms the hypothesis that growth and development at cold-hardening temperature are absolute requirements for the acquisition of resistance to photoinhibition at low temperature. |
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Keywords: | Chlorophyll fluorescence cold-hardening growth photoinhibition photosynthesis shift spinach Spinacia oleracea |
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