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The experiment described below was an attempt to measure the effect of differing leaf areas on the growth of the whole plant, the parts considered being the root system, parent stem, new shoot and, in particular, berries.
Measurements of berry volume and sugar suggested that there was a diphaslc growth curve and that with fall in leaf number there was a longer lag phase and a shorter second growth phase.
Growth rate in the second phase was not greatly affected. Acids fell more slowly where leaf number was less, and the sugar: acid ratio was reduced.
From final plant dry weights it was found that the trunk (parent stem) was least affected by loaf reduction, followed in order by shoot, berries and roots.
Sugars and starch in trunk and shoot were affected in a way similar to berries.
When needs of trunk, shoot and berries were fully met it appeared that excess leaf assimilate was channelled into root growth.
The minimal leaf area for unimpeded growth of aerial organs was estimated to be 1500cm2 (12 leaves).
The data has been interpreted to show that leaf efficiency in terms of carbon fixation was markedly increased with reduction in leaf number
The Effect of Reducing Leaf Area on the Growth of Roots, Stems and Berries of Gordo Grape Vines
1966, Sonderdruck aus der Zeitschrift ‘Vitis’, vol 5, pages 455 – 464
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