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Originally Posted by aruzinsky
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Your reference doesn't say that. ... YOU said "That is wrong because calcium does not travel down the phloem to the meristem." ... Your reference actually contradicts your statement as shown by your following quote. ... I think you misunderstand what is meant by the terms "mobile and immobile" of calcium in plants. Calcium is mobile in some plants and immobile in others such as Banana. Calcium is mobile in ALL plants from the roots to the parts of the plant it is used. But in some plants such as Banana calcium becomes immobile when it binds (fixes) in the plant cellular structure. That is it can not be reused in other parts of the plant.
You ignored my comment where I stated calcium didn't have to move down the meristem. It is directly applied where it is needed and absorbed by the leaf.
Quote:
Originally Posted by aruzinsky
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"Foliar applied calcium is normally immobile, but can be induced to translocate by the saturation of adsorption sites in the leaf with divalent cations or by chelation. Best evidence shows that the calcium moves in a reverse xylem flow down water‐potential gradients."
That suggests that it can move down the xylem, most likely when upward xylem flow stops during rain or high humidity. Still, a 10 foot petiole xylem is a very long distance to "flow down water‐potential gradients," so I doubt it.
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This is irrelevant to foliar spraying. The purpose of foliar spray is to by-pass the roots and meristem and apply nutrients directly where needed by the plant.
Quote:
Originally Posted by aruzinsky
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It's incumbent upon you to cite specific papers like I did. And, by that I mean about the efficacy of foliar feeding of calcium and nothing else.
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No it is not incumbent upon me to cite papers when my above comments were not based on them. Nor is it incumbent on me to do your leg work.
However, if you need further reading:
"
The movement of calcium in plants" by B. C. Hanger
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Calcium movement in plants is unidirectional, moving up from the roots and generally routed to meristematic zones and young tissue.
Once deposited in leaf tissue it is not recycled, even under calcium stress conditions. "
{ comment: this was what I basically stated in my posted comments and also above. ... And, Yes this is the paper YOU referenced. }
"
Application Strategies for Banana"
"Foliar application is used to address an immediate nutritional need or where soil conditions restrict availability of specific nutrients. It is also important to target the underside of the leaf as well as the top surface.
... Fruit applications are rare and often impracticable due to the use of bunch covers, though there is some indication
that calcium applied to the bunch can supplement existing reserves and improve fruit storage characteristics. "
"Selenium, zinc and calcium rich banana cultivation method "
(5) Foliar application: 10000-15000 fold diluted and selenium concentration and dilution of 0.3-0.5% Zn dilution and concentration of 0.5-1%
calcium fertilizer dilution, growth period in banana leaves surface spray 2-6 times.
[0005] Step (5) of the fertilizer is applied at the seedling stage banana, vigorous growth period, the two results of the spray flowering and fruit enlargement.
"
Crop Guide: Banana | Haifa Group"
Haifa Cal™ range of
calcium nitrate products offers ideal source of plant-available calcium for all crops and growing methods. Haifa Cal products contain nitrogen in the form of nitrate (NO3-), which enriches plant nutrition and improves the efficiency of calcium uptake.
Haifa Cal™ products are suitable for highly-efficient applications by Nutrigation™ (fertigation) and
foliar sprays, as well as soil applications.
Banana guide: fertilization recommendation
4.7 Foliar feeding
The plant roots readily absorb most mineral nutrients. However, many other plant organs are able to absorb nutrients in their ionic form from solutions. The extensive area of plant leaves makes them a natural candidate as a complementary feeding channel. Indeed, this method is now widespread in feeding management of many crops. The unique advantages that this method offers for banana growers are as follows:
- When the banana crop require plant nutrients, which are fixed and immobile in the soil.
- When deficiencies are detected at advanced stages of plant growth, and a quick correction is necessary.
- When root activity is hampered by external stresses such as low soil temperature, poor aeration, nematodes, rodents, or damage by machinery.
- When the effectiveness of direct soil application is limited due to weed infestation. As foliar application bypasses weed competition, this method ensures high availability to the target organs.
- When the roots are unable to provide the plant with certain nutrients at adequate rates, during specific critical stages of growth. This syndrome may take place even in fertile soils.
4.7.1 Foliar feeding practices
In Martinique, Philippines, Colombia and elsewhere it has become a prevailing practice to apply Haifa Bonus npK at a rate of 70 -100 g/mat (25-30% of the yearly potassium requirement) at the time of bunch initiation. The high availability of Haifa Bonus npK to the plant makes it the best fertilizer in meeting the plant’s increasing demand for nutrients at this critical stage of plant development that determines yield.
In Colombia, Mexico and elsewhere, foliar sprays during the vegetative growth and bunch development were found to be remarkably beneficial in increasing bunch weight, number of hands per bunch and number of fingers per hand (Tabs. 50, 51).