Author Topic: Citrus 'Node Count'  (Read 3286 times)

jcaldeira

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Citrus 'Node Count'
« on: December 24, 2014, 12:56:14 AM »
There was a concept of 'node count' promulgated on the old Gardenweb and Forumup forums that basically stated that a grafted scion/budwood, or a cutting, 'remembers' its maturity and will express sexual maturity depending on this node count.  It's my understanding that a 'node' is essentially equivalent to a growth flush.  Seems reasonable, but I think there's more going on.

It's clear that grafted citrus and branch cuttings flower sooner than their seedling brethren that are focused on vertical growth to capture sunlight and root growth to ensure survival.  However:
 
(1) A farmer near me has an old seedling lime tree that was broken off near the soil line during a cyclone two years ago.  The root suckers are now blooming in abundance.  The root suckers should have a single digit node count, yet mature at 24 months.

(2) There is evidence that flowering can be accelerated by grafting a young seedling scion onto a mature tree, so the mature tree pushes the scion a lot.  Thus it seems flowering is also influenced by the rootstock.

(3) I've had some 10 month old rough lemon seedlings bloom after being stressed to near death with lack of water, while the better-cared for seedlings did not.

Is it really node count, or is flowering a much more complex event?
« Last Edit: December 24, 2014, 09:53:51 AM by jcaldeira »
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Millet

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Re: Citrus 'Node Count'
« Reply #1 on: December 24, 2014, 01:28:52 PM »
A node is anyplace a leaf is attached to the tree.  The space between leaves (i.a. between nodes) is called an internode. The amount of time between planting a citrus seed and the start of flowering is different depending of the variety. Some flower in a year or two, while others can take 10+ years. In other words, different citrus varieties require different quantities of nodes before the variety becomes mature, and begins to flower.   A key lime has a small note requirement, therefore can start to flower in the 1st or 2nd year.  A grapefruit with a high node requirement can take 8 to 10 years and sometimes even longer to finally reach the required number of nodes, before the tree matures and begins to flower and fruit. A procimquat can flower if just a few months. I would not think maturity is influenced by rootstock. When a seedling is grafted onto an old mature tree, it might grow faster (?), but it will still have to reach the required number of nodes required by its particular variety. - Millet

jcaldeira

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Re: Citrus 'Node Count'
« Reply #2 on: December 26, 2014, 10:13:21 PM »
Can a West Indian Lime seedling really fruit in two years?  I know grafted ones can, but a seedling?  The one near me was broken right at ground level from a cyclone in December of 2012, which should be close to node zero, and now it's covered in fruit at 24 months.

Has anyone else noticed that water at the end of a drought stress promotes blooming in very young citrus?
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Millet

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Re: Citrus 'Node Count'
« Reply #3 on: December 26, 2014, 11:18:45 PM »
The answer is yes a key lime can indeed flower in its 2nd year of life.  In a experiment to verify this, I grew a key lime and indeed it did flower and fruit in its 2nd year. In tropical climates, which do not have cold periods to promote flowering,  drought is the common stress that promotes flowering.  The flowering starts after the drought period, when the rains return.  However the tree that blooms still must be a mature tree. Plain and simply,  juvenile trees are unable to flower . - Millet