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DTSTART:20140330T030000
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BEGIN:VEVENT
DTSTAMP:20260504T123154Z
UID:50040450b7806@ist.ac.at
DTSTART:20140120T163000
DTEND:20140120T173000
DESCRIPTION:Speaker: Tomas Bohr\nAbstract: Plants have highly effective vas
 cular systems\, which can transport fluid over large\ndistances. The xylem
  system carries water from the roots up to the leaves and the phloem\nsyst
 em carries sugar solutions from sugar sources (leaves) to sugar sinks (roo
 ts\, fruits etc.)\nand thus provides the necessary material for growth. Th
 ere are many important fluid\ndynamical problems connected with these flow
 s\, and I shall discuss some of them. In the\n1920’ies\, Ernst Münch pro
 posed that sugar transport in the phloem is driven by passive\nosmotic pre
 ssure gradients generated by loading and unloading sugar into the phloem\n
 tubes (sieve elements) of the leaves. It has been strongly debated whether
  this hypothesis\ncan actually account for long distance translocation\, e
 .g.\, all the way from canopy to root\nof a large tree. In the lecture\, I
  will argue that optimization of the efficiency of the sugar\ntransport le
 ads to a universal scaling of the width of the phloem tubes with the loadi
 ng\n(leaf) length and the translocation (stem) length in plants. These pre
 dictions have been\ntested for plants ranging from 10 cm herbacious plants
  to 60 m trees - both hardwood and\nconifers - and provide the first quant
 itative test of Münch’s ideas. For both the xylem and\nthe phloem\, the 
 leaves provide the driving force for the sap flow\, and I shall discuss\nc
 urrent ideas how this complex feat is accomplished.
LOCATION:Raiffeisen Lecture Hall\, Central Building\, ISTA
ORGANIZER:ihetzenauer@ist.ac.at
SUMMARY:Tomas Bohr: Institute Colloquium: The rise and fall of the sap: Mec
 hanisms of fluid flow in trees
URL:https://talks-calendar.ista.ac.at/events/501
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