TY - JOUR
T1 - Changes in photosynthesis and chlorophyll a fluorescence in relation to leaf temperature from just before to after harvest of Vitis vinifera cv. Shiraz vines grown in outdoor conditions
AU - Greer, Dennis H.
N1 - Publisher Copyright:
© 2021 The Author(s) (or their employer(s)). Published by CSIRO Publishing.
Includes bibliographical references
PY - 2021
Y1 - 2021
N2 - Harvesting fruit from horticultural species causes a down-regulation of photosynthesis but some species can recover after harvest. The objective of this study was to assess the hypothesis that the impact of fruit removal on the photosynthetic performance of Shiraz grapevines, in relation to CO2 concentration and leaf temperature, would contribute to a depreciation in photosynthetic assimilation. To assess this hypothesis, vines that were continuously vegetative were compared with vines that were harvested when fruit were ripe. These fruiting vines had higher rates of CO2-limited photosynthesis at all leaf temperatures compared to vegetative vines before harvest but after, photosynthetic rates were highest in vegetative vines. There were few treatment differences in CO2-saturated photosynthesis before harvest but after, below about 30°C, the harvested vines had higher photosynthesis than the vegetative vines. Maximum rates of ribulose 1,5 bisphosphate (RuBP) carboxylation and regeneration and responses to temperature were unaffected by differences in sink demand but after harvest, maximum rates increased, but markedly more in the vegetative vines, especially at higher temperatures. This conformed to higher photosynthetic rates in the vegetative vines. There were no sink demand effects on chlorophyll a fluorescence, consistent with the evidence that the fruit sink removal probably affected Rubisco activity and performance. The conclusion that sink removal caused a depreciation in photosynthesis was sustained but the temperature had a strong modulating effect through both stomatal and non-stomatal limitations driving the depreciation in assimilation. What was less clear was why assimilation of continuously vegetative vines increased during the harvest time when there were no apparent changes in sink demand.
AB - Harvesting fruit from horticultural species causes a down-regulation of photosynthesis but some species can recover after harvest. The objective of this study was to assess the hypothesis that the impact of fruit removal on the photosynthetic performance of Shiraz grapevines, in relation to CO2 concentration and leaf temperature, would contribute to a depreciation in photosynthetic assimilation. To assess this hypothesis, vines that were continuously vegetative were compared with vines that were harvested when fruit were ripe. These fruiting vines had higher rates of CO2-limited photosynthesis at all leaf temperatures compared to vegetative vines before harvest but after, photosynthetic rates were highest in vegetative vines. There were few treatment differences in CO2-saturated photosynthesis before harvest but after, below about 30°C, the harvested vines had higher photosynthesis than the vegetative vines. Maximum rates of ribulose 1,5 bisphosphate (RuBP) carboxylation and regeneration and responses to temperature were unaffected by differences in sink demand but after harvest, maximum rates increased, but markedly more in the vegetative vines, especially at higher temperatures. This conformed to higher photosynthetic rates in the vegetative vines. There were no sink demand effects on chlorophyll a fluorescence, consistent with the evidence that the fruit sink removal probably affected Rubisco activity and performance. The conclusion that sink removal caused a depreciation in photosynthesis was sustained but the temperature had a strong modulating effect through both stomatal and non-stomatal limitations driving the depreciation in assimilation. What was less clear was why assimilation of continuously vegetative vines increased during the harvest time when there were no apparent changes in sink demand.
KW - A/cc curves
KW - fluorescence
KW - modelling
KW - photosynthetic performance
KW - Shiraz grapevines
KW - sink demand
KW - sink removal
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U2 - 10.1071/FP21304
DO - 10.1071/FP21304
M3 - Article
C2 - 34883042
AN - SCOPUS:85121252976
VL - 49
SP - 170
EP - 185
JO - Functional Plant Biology
JF - Functional Plant Biology
SN - 1445-4408
IS - 2
ER -