Articles
DOWN-REGULATION OF PHOTOSYNTHESIS VIA SINK LIMITATION IS LINKED TO FOLIAR SOLUBLE SUGAR CONTENT IN HIGH- AND LOW-YIELDING VARIETIES OF SWEET CHERRY
Article number
1058_42
Pages
251 – 256
Language
English
Abstract
The objective of this study was to investigate the basis for yield differences between Kordia and Sylvia, low- and high-crop load carrying sweet cherry cultivars, respectively.
Branch girdling was effected on Kordia and Sylvia set up as Spanish Bush at Old Beach in the Derwent Valley, near Hobart, Tasmania, Australia.
Photosynthesis was measured with a Li-Cor 6400 four times pre- and once post-harvest.
Fruit set was 42% and 56% and fruitlet abscission was 69% and 34% in Kordia and Sylvia, respectively.
Maximum photosynthetic rate (Asat) increased from a low or around 12 µmol m-2 s-1 in early Spring to a maximum of around 18 µmol m-2 s-1 early Summer and was similar between cultivars pre-harvest.
However, post-harvest, Asat of Kordia was significantly lower at around 8 µmol m-2 s-1 relative to that of Sylvia at around 16 µmol m-2 s-1. Girdling had a stronger effect on Asat in the low-yielding Kordia than in the high-yielding Sylvia (-13% vs. -11%, respectively), and there was a greater increase in foliar soluble sugar (SS) content in Kordia than Sylvia (+18% vs. +13%), averaged across the season.
There was a strong negative correlation between SS and Asat in leaves, across the season, cultivars and treatments.
There were no girdling or cultivar effects on foliar starch content.
The results suggest that girdling-induced sink-limitation leads to down-regulation of photosynthesis that is linked to the accumulation of SS content in the leaves.
Despite minor differences in Asat between varieties, our results imply that the low-yielding Kordia variety is not limited by source-supply potential during the growing season, but that low Asat post-harvest could be linked to the subsequent seasons fruitlet abscission that limits potential yields.
Further investigation is warranted regarding carbohydrate storage as a factor in the relatively high fruitlet abscission in Kordia, and other low-yielding varieties of sweet cherry.
Branch girdling was effected on Kordia and Sylvia set up as Spanish Bush at Old Beach in the Derwent Valley, near Hobart, Tasmania, Australia.
Photosynthesis was measured with a Li-Cor 6400 four times pre- and once post-harvest.
Fruit set was 42% and 56% and fruitlet abscission was 69% and 34% in Kordia and Sylvia, respectively.
Maximum photosynthetic rate (Asat) increased from a low or around 12 µmol m-2 s-1 in early Spring to a maximum of around 18 µmol m-2 s-1 early Summer and was similar between cultivars pre-harvest.
However, post-harvest, Asat of Kordia was significantly lower at around 8 µmol m-2 s-1 relative to that of Sylvia at around 16 µmol m-2 s-1. Girdling had a stronger effect on Asat in the low-yielding Kordia than in the high-yielding Sylvia (-13% vs. -11%, respectively), and there was a greater increase in foliar soluble sugar (SS) content in Kordia than Sylvia (+18% vs. +13%), averaged across the season.
There was a strong negative correlation between SS and Asat in leaves, across the season, cultivars and treatments.
There were no girdling or cultivar effects on foliar starch content.
The results suggest that girdling-induced sink-limitation leads to down-regulation of photosynthesis that is linked to the accumulation of SS content in the leaves.
Despite minor differences in Asat between varieties, our results imply that the low-yielding Kordia variety is not limited by source-supply potential during the growing season, but that low Asat post-harvest could be linked to the subsequent seasons fruitlet abscission that limits potential yields.
Further investigation is warranted regarding carbohydrate storage as a factor in the relatively high fruitlet abscission in Kordia, and other low-yielding varieties of sweet cherry.
Publication
Authors
A.G. Quentin, D.C. Close, L.M.H.P. Hennen, E.A. Pinkard
Keywords
Prunus avium, branch girdling, fruitlet abscission, sink demand, fruit set
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