VARIABILITY IN CHLOROPHYLL, RUBISCO, AND FOURTH DERIVATIVE SPECTRA AND THEIR RELATIONSHIP TO CO2 ASSIMILATION RATES OF EIGHT FRAGARIA CHILOENSIS GENOTYPES

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  • 1 Washington State University Research and Extension Unit, 1919 N.E. 78th St., Vancouver, WA 98665

Gas exchange rates were measured in the field on middle leaflets of Fragaria chiloensis (L.) trifoliates which were then used for Rubisco quantity and activity assays. Side leaflets of the same leaf were utilized for fourth-derivative spectroscopy, chlorophyll extraction, and specific leaf weight data. Differences of CO2 assimilation (A) rates were highly significant between genotypes ranging from 16.2 to 27.6 μmol CO2·s·m. Chlorophyll a and b, and total chlorophyll per unit area were positively correlated to A (r = 0.48**, 0.45**, and 0.49**, respectively). Total chlorophyll per unit dry weight had a correlation coefficient with A of 0.6**.

Fourth-derivative analysis of in vivo leaf attenuance spectra showed a positive correlation between A and Ca693 peak amplitude and a negative correlation of A and Ca677 peak amplitude. Peak amplitude of Ca693 was also correlated with chlorophyll content.

Activity per unit Rubisco was not a significant factor influencing A, but Rubisco quantity on either a leaf area or a dry weight basis was positively linked to A (r = 0.40** and 0.44**, respectively).

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