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How to identify determinate and indeterminate plants

Posted by naturegirl_2007 5b SW Michigan (My Page) on
Thu, Jan 21, 10 at 21:08

Seems like I should know this, but I don't. What growth pattern(s) on the tomato plant show if it's DET or INT? I'm thinking DET shows as more than heavy fruit set followed by death. Should I be looking at flower location? Leaf arrangement? Internode length? Something else????

It seems like some seed packets and plant descriptions do not correctly identify the plants as DET and INT. Or is it just that some DET grow quite large and some INT are not vigorous growers? Maybe in my zone the DET never get to the point that they give out before frost gets them.


Follow-Up Postings:

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RE: How to identify determinate and indeterminate plants

For a discussion of the difference between indet and det varieties please click on the blue FAQ link at the top of this first page and the very first FAQ is the one you're after.

Carolyn


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RE: How to identify determinate and indeterminate plants

Here you go.

Dave

Here is a link that might be useful: How different types of tomato plants grow


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RE: How to identify determinate and indeterminate plants

You were ok to ask naturegirl because the information in the FAQ is misleading or incorrect.

The only way to truly tell a determinate from an indeterminate is to look at how many leaf attachments (nodes) occur between flower clusters. Not plant habit or harvest interval.

Determinates will produce a shoot that will have 0 to 2 leaf nodes and then terminate in a flower. New shoots form in the base of those nodes which give it a bushy appearance.

Indeterminates will have 3 or more nodes between flower clusters. The explanation of exactly how an indeterminate grows is a little complex so I will refer to another text. I also added in the information about semideterminate plants (like 'Celebrity').

From:
'Sustainable Practices for Vegetable Production in the South' Mary Peet, 1995.

Although indeterminate plants appear to have a single main stem, this is actually not the case. The growth of the primary shoot ends with the formation of the first flower. Upward growth continues because the last leaf initiated before the flower cluster (which actually grows to occupy a position above the cluster) produces a side shoot. This side shoot produces three more leaves before it terminates in a flower cluster. The process of initiating new growth from a side shoot of the last leaf initiated before the flower cluster continues indefinitely, giving the appearance of a mainstem with a flower cluster between every three leaves.

.....Shoots of semideterminate plants produce several flower clusters to the side of an apparent main stem, like indeterminates, but eventually the shoot terminates in a flower cluster, as in determinate plants.

Here are some of the misleading things mentioned in the FAQ:


  • Determinates have a bushier appearance. However, some indeterminates can also have a bushy appearance if they have genetics which shorten the distances between nodes (various dwarfing or habit related genes).

  • Not all determinates produce fruit in a concentrated set over a two week period. Some determinate fresh market cultivars are capable of producing 3-4 harvests over the course of 6-8 weeks depending on conditions. Some determinates, like those bred for canning and mechanical harvest, have been selectively bred to ripen all at one time.

  • Determinates can benefit from selective pruning. This is done by removing all young sideshoots that occur in the leaf axils below the first flower cluster and then stopping. This will open up the lower canopy for air flow and less plant material will be touching the ground which can reduce pathogens. This kind of pruning has also been shown to give a slight increase in earliness over leaving alone. This practice tends to be a growers choice.


    1995. Dr. Mary Peet.


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RE: How to identify determinate and indeterminate plants

The page Dave hyperlinked to gives very good information about the differences between determinate and indeterminate tomato vines.

For those who rather not or cannot click to external links, here are a few bits of info that El Burro (Mulio) gave me a couple years back that I've found helpful when looking in detail at vine growth characteristics:

Indeterminate and Determinate: Five to 10 leaf fronds emerge out of the primary shoot of a young tomato vine before a flower cluster emerges. That means there will be at least 4 internodes and up to 9 internodes (stem segments between leaf axils) before a flower cluster appears on the vine.

Indeterminate: Although indeterminate plants appear to have a single main stem, this is actually not the case. The growth of the primary shoot ("main stem") ends with the formation of the first flower. Upward growth continues because the last leaf initiated before the flower cluster (which actually grows to occupy a position above the cluster) produces a side shoot. This side shoot produces three more leaves before it terminates in a flower cluster. This process of initiating new growth from a side shoot of the last leaf initiated before the flower cluster continues indefinitely, giving the appearance of a mainstem with a flower cluster in the internode between every three leaf nodes. Examples: Big Boy, Better Boy, Brandywine, Big Beef, Sun Gold, many heritage types.

Determinate: In determinate cultivars the process differs in that the side shoot above the first flower cluster produces 0 to 2 leaf nodes and a flower cluster but no further vegetative shoots. This ends the upward growth of the plant, making the apparent main stem much shorter. Many side shoots arise from the primary shoot, giving the plant a bushy appearance, but each eventually terminates in a flower cluster as did the primary shoot. The simultaneous growth of many flower clusters on determinate vines promotes earliness and concentrates fruit maturity compared to indeterminates. Examples: Mountain Spring, Scarlet Red, Mozark, most modern commercial canners.

"Semi-determintes:" Shoots of semi-determinate plants produce several flower clusters to the side of an apparent main stem, like indeterminates, but eventually the shoot terminates in a flower cluster, as in determinate plants. Example: Celebrity (and for me, the Bradley tomato I've grown for several years now).

So the basics are:

Indeterminate: After the first flower cluster emerges, then 3 or more nodes between subsequent flower clusters.

Determinate: After the first flower cluster emerges, then 0 to 2 nodes between subsequent flower clusters.

Any questions regarding the information above may be addressed to His Muleness.

Bill


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... nevermind ...

Well, howdy doody! I see His Muleness already posted the same info as I was assembling my post. LOL!


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RE: How to identify determinate and indeterminate plants

That FAQ I referred to was here when I first came to GW, and I don't think I ever read it in it's entirety, so I apologize if I referred to a FAQ that had errors in it.

A woman who was here in the late 90's, I didn't know her but heard about her from others, was the one who got some of those FAQ's up when Spike ( former owner of GW) split off the tomatoes from the Vegetable Forum and I was told she was quite knowledgeable. I know the variety FAQ is very out of date, that's for sure.

But there are other FAQ's that were done much more recently as a group project that I think are pretty darn good.

Carolyn


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RE: How to identify determinate and indeterminate plants

WHAT! You didn't read the FAQ!

watch out! there may be a pop quiz later


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RE: How to identify determinate and indeterminate plants

Someday people will stop the FAQ blah, blah, blah here and just answer the damn person's question. People are free to ask whatever they want to ask no matter how much it's been beaten to death before. Thats the whole point of a DISCUSSION forum. Faq this....i need a drink!


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RE: How to identify determinate and indeterminate plants

OH, WOW! I didn't expect to stir up such passion when I asked the question. I have found various places, including the FAQs, that give short explanations that don't seem to match what I see in my plants. That's what lead to my original post. I don't consider Celebrity or Rutgers particularly bushy plants and mine have ripened fruit over several weeks. And I don't believe they ever died from "old age." Granted we do have a somewhat short growing season. Yet both varieties are called DET in many places. The more detailed answers given here are very helpful and I thank you for them.

I'll be counting leaves and flower clusters this year and looking more closely at how parts are arranged on my plants. Might even add a determinate variety or two just to study the leaf and flower arrangement and see if I can actually get them to die of old age.


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RE: How to identify determinate and indeterminate plants

With regard to determinates "dying of old age," I've seen all the shoots on some determinate varieties terminate in flowers and I guess just atrophy or completely shut down and die a slow death that appeared to be the result of photosynthesis shutdown, or shutdown of nutrient delivery through the vascular tissue or something that might equate with "dying of old age" were it an animal rather than a plant.

This happened in more than one year for example with Ditmarsher, Mozark, short stake plum/roma commercial type canners and a couple of determinate dwarf varieties I've grown, foliar diseases not withstanding.

On the other hand, I've had determinates like Celebrity and Bradley continue to grow and produce new fruit, although rather less robustly, until a killing frost.

With some varieties, like Ditmarsher (a tumbler variety) for one example, I've cut the vines off near the root crown, re-fertilized, and stimulated new aventitious shoots that grew into new plants when the season was long enough.


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