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Daily photosynthetic and C‐export patterns in winter wheat leaves during cold stress and acclimation
Author(s) -
Leonardos Evangelos D.,
Savitch Leonid V.,
Huner Norman P. A.,
Öquist Gunnar,
Grodzinski Bernard
Publication year - 2003
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 - 10.1034/j.1399-3054.2003.00057.x
Subject(s) - photosynthesis , acclimatization , biology , botany , overwintering , biomass (ecology) , horticulture , zoology , agronomy
Diurnal patterns of whole‐plant and leaf gas exchange and 14 C‐export of winter wheat acclimated at 20 and 5°C were determined. The 5°C‐acclimated plants had lower relative growth rates, smaller biomass and leaf area, but larger specific leaf weight than 20°C plants. Photosynthetic rates in 20°C and 5°C‐acclimated leaves were similar; however, daytime export from 5°C‐acclimated leaves was 45% lower. Photosynthesis and export remained steady in 20°C and 5°C‐acclimated leaves during the daytime. By comparison, photosynthesis in 5°C‐stressed leaves (20°C‐acclimated plants exposed to 5°C 12 h before and during measurements) declined from 70 to 50% of the 20°C‐acclimated leaves during the daytime, while export remained constant at 35% of the 20°C‐acclimated and 60% of the 5°C‐acclimated leaves. At high light and CO 2 , photosynthesis and export increased in both 20°C and 5°C‐acclimated leaves, but rates in 5°C‐stressed leaves remained unchanged. At all conditions daytime export was greater than nighttime export. Taken together, during cold acclimation photosynthesis was upregulated, whereas export was only partially increased. We suggest that this reflects a requirement of cold‐acclimated plants to both sustain an increased leaf metabolic demand while concomitantly supporting translocation of photoassimilates to overwintering sinks.