New Zealand Journal of Crop and Horticultural Science abstracts
Intra-plant differences in leaf chlorophyll fluorescence parameters
in perennial fruiting plants
J. G. BUWALDA
The Horticulture and Food Research Institute
of New Zealand
Ruakura Research Centre
Private Bag 3123
Hamilton, New Zealand
G. NOGA
Institut für Obstbau
Universität Bonn
Auf dem Hügel 6
D 53123 Bonn, Germany
Abstract Chlorophyll fluorescence analysis was used to
examine intra-plant differences in the activity of photosystem II (PS II)
associated with source : sink balance, in mid summer, on pear
(Pyrus communis L.), plum (Prunus domestica L.), and apple
(Malus domestica L.) trees growing in the field. For all three species,
maximal fluorescence, Fm, and the ratio of variable to maximal fluorescence for
dark adapted leaves, Fv/Fm, were significantly higher for leaves from fruiting
spurs (Fv/Fm averaging 0.83) than for leaves from extension shoots (Fv/Fm
averaging 0.81). Significantly higher non-photochemical quenching (qN) of
fluorescence for leaves on extension shoots (averaging 0.41) compared to leaves
on fruiting spurs (averaging 0.38) was consistent with "down regulation" of
photosynthesis. For pear, qN was lower than for plum and apple, indicating
inter-specific differences in mechanisms of resistance to photoinhibition. For
apple, qN was significantly lower for leaves in shaded portions of the canopy
(0.33), compared to that for leaves in exposed portions of the canopy (0.37).
The quantum efficiency of photosynthetic electron transport, [[Phi]]e, measured
in the field at varying quantum flux density (Q), did not differ
significantly for leaves on extension shoots or spurs, for any species tested.
For apples, Fv/Fm was significantly lower for leaves on trees that had been
deblossomed early in the season (averaging 0.81), than for leaves on trees with
fruit (averaging 0.82). This difference was mostly the result of increased
basal fluorescence (Fo). [[Phi]]e decreased with increasing Q more
rapidly for trees without fruit than for trees with fruit.
Keywords apple; Malus domestica; chlorophyll
fluorescence; pear; Pyrus communis; photosynthetic electron transport;
plum; Prunus domestica; source:sink balance
New Zealand Journal of Crop and Horticultural Science, 1994, Vol. 22:
373-380
0114-0671/94/2204-0373 $2.50/0 (c) The Royal Society of New Zealand
1994
PDF file of entire paper: medium quality (598K); (scanned from paper original: notes about this process)
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