Author:
Bungard Ralph A.,McNeil David,Morton James D.
Abstract
Effects of nitrogen supply (N-supply) on the photosynthetic apparatus of
Clematis vitalba L. grown at several irradiances were
determined by measuring soluble protein content, rubisco activity,
photosynthetic pigment content and composition, and the photochemical
efficiency of photosystem II
(Fv/Fm).
Compared to low irradiance (3 and 10% full sunlight), leaves grown at
higher irradiance (up to full sunlight) had up to 5–6 times the soluble
protein content and rubisco activity, and up to 2–4 times the total
carotenoid content, on both a leaf area and a chlorophyll basis. On a leaf
area basis, decreased N-supply reduced soluble protein concentration, rubisco
activity and total carotenoid concentration to a greater extent at high
compared to low irradiance. On a chlorophyll basis, in contrast, soluble
protein and rubisco activity decreased by over 40% with increased
N-supply (1.0–0.1 mol m-3) at high irradiance but
N-supply did not influence the concentration of total carotenoids. Leaves
grown at high compared to low irradiance had a greater concentration of
xanthophyll cycle pigments (V+A+Z), β-carotene and lutein (but
not neoxanthin) on a chlorophyll basis, and a slightly lower
Fv/Fm.
Nitrogen- supply did not influence the composition of the photosynthetic
pigment pool,
Fv/Fm,
or the extent of de-epoxidation of the V+A+Z pool. The results
suggest that irradiance-acclimation of C. vitalba can
occur regardless of N-supply. Under N limitation at high irradiance, a balance
between light capture and photosynthetic capacity is important rather than an
increase in xanthophyll cycle-dependent energy dissipation. The importance of
lutein as a light-harvesting pigment is questioned. A rapid method for the
reversed phase-HPLC separation of carotenoids is described.
Subject
Plant Science,Agronomy and Crop Science
Cited by
56 articles.
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