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What makes tomato sweet?

Posted by lindalana z5 IL (My Page) on
Tue, Oct 8, 13 at 21:38

Does P and K influence sweetness? My tomatoes were just a bit more tart compare to same tomatoes- grown from my seedlings- by other people. Am wondering how much influence -which minerals give to add to the sweetness.

Follow-Up Postings:

RE: What makes tomato sweet?

watching this post to find out....I do know that other fruits are very dependent on heat to sweeten up fruit.

RE: What makes tomato sweet?

The primary determinate of sweetness for a given variety are the GENES that it has.

Beyond that you'll find all kinds of opinions of what makes for sweetness and most of the links below don't even mention the most important one, which are the genes.

So in some of the links below you'll find using organic fertilizer, certain chemicals, and on and on and on caninfluence sweetness.

Expression of genes can also be variable, since one relys on photosynthesis to make the energy compounds that allow for good gene synthesis of proteins that are involved in making the various sugars found in fruits, and if the sun doesn't shine, less energy compounds made, well, you get the picture..

My own philosophy is if you grow a variety under your conditions, your soil or container mix,using what amendments you use, and if so when and how much, what the weather is in any given season, and many more variables, and you grow it at least TWICE, if someone else said it was sweet for them and it wasn't for you, then.

......... switch to a different variety. ( smile)


Here is a link that might be useful: What makes tomatoes sweet

RE: What makes tomato sweet?//

And I forgot something really Important, and that's that TASTE is both perceptual and personal, meaning not all taste fruits the same, and there's even a human genetic factor involved.

I used to do lots of taste testings for others and I supplied ALL the fruits, and one person would say, this one is so sweet, and another person tasting the SAME fruits would say too bland, or too aggressive.

So don't forget the variable of taste being perceptual and personal. What I might praise highly, someone else would have a completely different opinion.


RE: What makes tomato sweet?

My first question would be why you think P and K are the thing to focus on?

I can think of at least 20 factors - genetics aside - that can affect the flavor of a fruit. Even the flavor of 2 fruit from the same plant eaten on the same day much less fruit from different gardens.

That these plants were all your seedlings isn't relevant. With the same variety, a seedling is a seedling is a seedling.

Clearly if one knows for a fact that their soil's P and/or K is out of whack then it should be fixed. But an insufficiency of them is rare.

The value of "taste" as an evaluating tool is nil. As Carolyn said, it is totally subjective. It changes from hour to hour in the same mouth depending on the moisture level in the mouth and what the taste buds were last exposed to. It is a wild variable that cannot be stabilized or controlled except in lab conditions. So making comparisons based on it, much less lasting decisions based on it, are really pointless.


RE: What makes tomato sweet?

My best results have been from doing everything I can to improve growing conditions. This means adding HUGE amounts of organics to the soil, keeping diseases under control, and ensuring maximum sunlight. Genetics still has the most to do with getting sweet tomatoes.

I have this saved from Keith Mueller from a 11 years ago.

I spent several summers taking brix measurements in replicated tomato plots. I probably have the notes around somewhere. Most where breeding lines though some were heirlooms.

BUT from that:
In the hot drier summer brix went up in all varieties.

Going back to the original question, I find that (when possible) cutting back on watering when the majority of fruit are ripening intensifies flavor/sugars. Melons do this too, its one of the reasons I personally dislike plastic mulch.

from what I recall
(Sun Gold->Sugar->Sweet Chelsea->Green Grape)
being the sweetest

I had one sungold reading that was a 12 (highest reading that year). Most sungolds where around 8-11.

Sugar didnt have any 12 but had less of a range 9-11, with most being up around 10.5

green grapes were 8-9
most other cherries were 5-8

I dont recall the larger fruited varieties values.



RE: What makes tomato sweet?

I can sure attest that to melons. We used to grow melons at places where no water supply was avail so summer with some rain during June and July but dry and hot August is ideal for great melon taste.

RE: What makes tomato sweet?

Unless a tomato is taken to a laboratory and its sugar contents measured in most cases it is a "perceptive" thing, as Carolyn said. Obviously gene is the most powerful determining factor. Climate, sunshine, amount of water/rain are other influences.
Then again, this reminds me of Jonathan Swift's Gulliver's Travels. It is all relative.

RE: What makes tomato sweet?

Lindalana, how does the size of your tomato plants that were more tart compare to those of other people that were sweeter? Did yours have fewer leaves or did your leaves suffer from disease stress?

The reason for my question is because I think the sweetness of a tomato will depend on the amount of sugar that the leaves provide through photosynthesis. Fewer leaves, less sugar.

I find my tomatoes don't get really sweet until later in the season when the plants are at their peak with lots of leaves.
I encourage early fruit when the plants are small, using cold treatment, since I have a fairly short season. These early fruits never get all that sweet.
At the end of the season, once disease strips most of the leaves off of a plant, the resulting tomato is noticeably less sweet.

RE: What makes tomato sweet?

BriAnDaren, you might be onto something as I did have pretty bad septoria this year so lots of leaves clean up happened.
So general consensus seems to be as fusion power says- improve growing conditions as much as one can by providing huge organic component to soil, keep away from disease and ensuring plenty of sunlight. Rest of it just genes and personal taste. Sounds pretty simple but not easy! LOL

RE: What makes tomato sweet?

Tomatoes accumulate sucrose which is produced in the leaves via a complex series of steps starting with water and carbon dioxide from the air. Vacuolar invertase breaks the sucrose down into glucose and fructose for further metabolism. Variations in the gene that produces vacuolar invertase and a few others associated with it result in sucrose accumulation in the fruit. LA4104 from TGRC has a variant of this gene that causes more sucrose to accumulate in the fruit.

If you want to have sweet flavor, you have to go back to plant health to ensure the leaves have everything needed to produce sugar in the first place. Once it is produced, it must be readily transported to the fruit. Once in the fruit, it has to be stored instead of being metabilized for fruit growth. That means a LOT of genes are involved in the processes and therefore there is a LOT of room for genetic selection.

With that said, get some Crnkovic Yugoslavian seed and see what you think.

RE: What makes tomato sweet?

Yes, lots of steps and enzymes involved, but none of that can happen unless photosynthesis produces the energy compounds ATP and GTP which are necessary to faciliate those reactions and end products.

So IMO conditions that lead to the most efficient photosythesis are the most important.

I still say that taste is in the mouth of the one tasting fruits and taste is perceptual and personal and depends on many other variables.

I can taste variety A and think it's sweet but another person can taste it and say it's a spitter.

BRIX levels measure soluble sugars, all of them,not just sucrose.

Crnkovic Yugoslavian? Yes, a variety I introduced by first listing it in the SSE YEarbook. From a fellow faculty member Yasha Crnkovic. And I've grown it a lot. Is it the sweetest variety I've ever tasted? I don't think so but it's a great variety IMO as well.


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