The role of phosphate in fruiting plants
 

I'm hoping that adrift, Ohio's Best, sbl, Scot Nelson, turtle, and all of you other well-qualified biologists can help out with this one.

I have read a lot over the years about the role of phosphate in fruiting plants. For bananas, one researcher reports that there is negligible uptake and less than an ounce (net weight) per plant per year is needed. In a UC Davis handbook on peach orchards I read that the role of phosphate is to stimulate root development which in turn makes it possible for the plant to generate a larger volume (number) of flower buds. A report from the plant science department at Cal Poly states that potash works just as well as phosphate for the production of blooms in plumerias (ok, its not a fruiting plant per se).

So what is the current knowledge of the role of phosphate in say: bananas, pit fruits, and subtropicals such as citrus and guavas?

Re: The role of phosphate in fruiting plants
 

Good Question!

I do not know all of the roles of P in plants, but one critical role is in energy production and storage. Just like in animals ATP (Adenisine Tri-Phosphate) is the primary energy source for most reactions (like carbon fixation). After photosynthetic apparatus captures a photon the energy is stored as ATP. To drive a reaction that requires energy, the ATP is converted to ADP.

As a gardener (not as a scientist), I have always been told that extra P encourages flowering, while K supports root growth and N leaf growth, but I also know that e xcess P in soil can bind minerals and reduce their availabilaiy.

Re: The role of phosphate in fruiting plants
 

Turtile.

Re: The role of phosphate in fruiting plants
 

Thanks Sbl. Energy storage and release are going to be important factors for flower production. In terms of the gardening adage that "phosphate promotes blooms", is there a biological process in plants that underlies this observation?

Re: The role of phosphate in fruiting plants
 

Oh yeah, I forgot P is an important element in DNA---the nucleotides that make up DNA all contain P. Since flower and seed formation are basically a process of packaging DNA for future generation, P would be very important to the bloom process.

Re: The role of phosphate in fruiting plants
 

I have read that in the fruiting plants I'm concerned with, the ratio of N to P is about 50:1 to 60:1. Further, the uptake ratio of N to phosphate is said to be about 30:1, with 32:1 named specifically for a few plants (pit fruits, bananas). Anyone care to correct or clarify that?

Also, there is the practice of over-application of phosphate -- mainly because it is difficult to penetrate more than the 1st inch of the soil unless all the soil reactants are over-burdened with phosphate. This in part explains the application of high-phosphate formulas for bloom. But then of course we have the same phenomena in hydroponic culture where the reactants are negligible. So apparently there is a lot more to the story. I'm hoping one of you botanists/biologists has the answer or a good reference on the subject. Thanks!

Re: The role of phosphate in fruiting plants
 

I remember reading one article that provided uptake ratios over the life of a flowering plant (annuals)--P uptake is higher in the last part of a plant's life relative to N.

Here are a couple links I just found: http://www.kmag.com/assets/pdf_files/efu/Phosphorus.pdf

Phosphorus (P) Basics

Re: The role of phosphate in fruiting plants
 

Phosphate is definitely the energy carrier in the plant system, it is important for both bloom and root growth. It is not soluble and gets tied up with calcium or aluminum/iron depending on the pH of the soil. Basically, the plant is going to set as many blooms as it thinks it will be able to based on its nutrition at the time it decides to bloom. Bananas don't have much DNA to make since they don't have seeds.

Re: The role of phosphate in fruiting plants
 

Most of the extra phosphorus found in the soil in my area is due to the use of chicken manure which is high in phosphorus.

Banding is the best way to apply phosphorus. It minimizes reversion (available forms of P turn to less available) since it has less contact with soil. There is also a phosphorus fertilizer called Avail which keeps P in a more available form longer.

All cell reproduction requires the replication of DNA regardless of the way the plant reproduces.



Phytin in seeds contains a good amount of phosphorus which is released when the seed begins to grow.

Re: The role of phosphate in fruiting plants
 

This a indepth discussion... Anyone have an answer to why my Velenica Orange is fall blooming? lol I can only hope it doesn't freeze and I'll have spring orange juice. :^)

Re: The role of phosphate in fruiting plants
 

Ha! Your Valencia orange is acting normally.
I have also my clemenule mandarin blooming and my calamondin blooming all year round. But don't count your glass of orange juice ahead of time because good ole Frost is jutting its head around the corner. In fact I have more citrus have many marble size fruits right now like my Washington navel, Trovita Orange etc....And to think that my dwarf orinoco had just weaned its male flowers.So I don't know what will happen.

Re: The role of phosphate in fruiting plants
 

Citrus blooms are the result of a transformation (differentation) of growth buds into flowers. There are several factors that can affect that process. It is often said that "stress" will cause citrus to bloom, cold stress, water stress are considered to be the normal stress that initiates the bloom. In either case, there is a rest period that gives the plant time to convert a growth bud into a flower, so a slow growing plant is more likely to produce fall blooms.

Re: The role of phosphate in fruiting plants
 

Thanks for that tidbit.. I'm not putting it in a pot to get a glass this spring. I'd rather clip them to strengthen the plant in the yard.. Patience is virtue. I'd say I have time on my side and grapefruits.. lol Still waiting on my second yield from my figs.. just seems late this year due to summer drought most likely.. ?