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BIOCHEMICAL STRATEGIES FOR GROWTH OF GRACILARIA TIKVAHIAE (RHODOPHYTA) IN RELATION TO LIGHT INTENSITY AND NITROGEN AVAILABILITY 1
Author(s) -
Lapointe Brian E.,
Duke Clifford S.
Publication year - 1984
Publication title -
journal of phycology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.85
H-Index - 127
eISSN - 1529-8817
pISSN - 0022-3646
DOI - 10.1111/j.0022-3646.1984.00488.x
Subject(s) - phycoerythrin , biology , light intensity , growth rate , acclimatization , photosynthesis , rubisco , nitrogen , botany , phycocyanin , zoology , phycobiliprotein , dry weight , pigment , allophycocyanin , photosynthetic pigment , food science , cyanobacteria , chemistry , microbiology and biotechnology , bacteria , flow cytometry , physics , geometry , mathematics , organic chemistry , genetics , optics
The main effects and interactions between light (I o , full incident sunlight to 0.07 I o ) and NO 3 − loading (0.4 to 4.3 mmol · g dry weight −1 · d −1 ) on growth rate, photosynthesis and biochemical constituents of Gracilaria tikvahiae McLachlan were studied using a factorial design experiment in outdoor, continuous‐flow seawater cultures. Incipient nitrogen limitation in the low NO 3 − loading, I o and 0.57 I o treatments occurred after 2.5 weeks of growth under the experimental conditions and resulted in decreased tissue NO 3 − and R‐phycoerythrin. Tissue NO 3 − and R‐phycoerythrin accounted for up to ca. 15 and 20%, respectively, of the total N in G. tikvahiae suggesting a N reserve role for these N pools. Under light and NO 3 − limitation, growth rate was a parabolic function of the C:N ratio. As light limitation increased, growth rate and the C:N ratio decreased as levels of Chl‐a, R‐phycoerythrin, percent N and percent protein increased. As NO 3 − limitation increased, growth rate and levels of Chl‐a, R‐phycoerythrin, percent N and percent protein all decreased with parallel increases in the C:N ratio. In contrast to the inverse relationship between pigment content and light, ribulose bisphosphate carboxylase (RuBPCase) activity (on both a protein and dry weight basis) varied directly with light. This biochemical acclimation of G. tikvahiae to light and N availability appears to be a process directed towards maximizing photo synthetic capacity and growth.