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Old December 6, 2012   #50
Fusion_power
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Join Date: Feb 2006
Location: Alabama
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I'm laying out the objectives for this cold tolerant tomato. I am going to incorporate breeding lines with red, pink, and black fruit colors and will not use white, yellow, or orange because of difficulties with flavor. I see three significant high level objectives and hurdles.

The first is foliage tolerance to cold temps, in other words, does not freeze. This trait would be useful in both early and late season, but would be most effective for spring planting prior to settled warm weather. This trait will be the highest priority since it is already available in some lines.

The second is fruit tolerance to cold. Since tomatoes are mostly water, I expect this will be a very difficult objective. I expect this trait will come from one or more wild species because I can not find any reference to such tolerance in domestic tomatoes. I have observed volunteer S. Pimpinellifolium plants in my garden that produce fruit that are not damaged down to 25 degrees so the outlook for this trait is very good.

The third is to develop a very good flavored tomato that maintains high eating quality even when fruit mature at low temps. I think this trait can be incorporated in combination with both of the traits listed above, but I will note that even a moderately good flavored tomato would be a major achievement given the current status of available varieties.

A. must be able to tolerate extremely low temps (Fahrenheit) to be scored for the following temperatures: 28°, 25°, 22°, 15°, 0° where:
1 = foliage unaffected, no frost damage
2 = foliage lightly affected, frost damage minimal
3 = foliage minimally affected, light to moderate frost damage, plant growth minimally slowed down
4 = foliage significantly affected, up to 50% of foliage with frost damage
5 = Major leave damage, plant unlikely to recover

B. Fruit must be able to tolerate freezing temps scored for the same temps as:
1 = no frozen fruit, no water blemishes
2 = no frozen fruit, minimum water blemishes
3 = no completely frozen fruit, some water freeze damage blemishes
4 = some fruit frozen, significant water freeze damage
5 = Most fruit damaged, watery, inedible

C. Flavor must be maintained both as a summer crop and when matured at average temps below 45°. I am setting the bar very high for flavor, I will set Eva Purple Ball as 5 - mediocre summer flavor for the standard!
1 = Excellent summer flavor, Excellent cool season flavor
2 = Excellent summer flavor, Very good cool season flavor
3 = Very good summer flavor, Good cool season flavor
4 = Good summer flavor, Mediocre cool season flavor
5 = Mediocre summer flavor, Poor cool season flavor

Here are the genes and traits I want to incorporate and the rationale behind each:

1 - Jointless - this will allow fruit to be picked without stem punctures
2 - High Lycopene, high vitamin C, high vitamin A - enhances fruit $ value and adds nutrition value
3 - Size - to be defined as approximately 2.5 to 3.5 inches diameter fruit (Eva Purple Ball)
4 - Fruit to be round, not oblate - This will give more leeway when introgressing traits from wild species which tend to be round
5 - Precocious flowering - This trait is significant for early fruit maturity
6 - Fruit maturity in 65 days - This trait enables early season harvest, we want good flavored tomatoes EARLY
7 - Balanced flavor - Not sour, not tart, rich tomato essence with just the right amount of sugar
8 - Highly disease tolerant - Some of the genes desired are ph0, ph1, ph2, ph3, ph5 (late blight), I1, I2, I3 (fusarium), sw5, sw7(tomato spotted wilt), mi1, mi9 (nematodes), tm2 (tobacco mosiac virus), sm (stemphyllium), cf1, cf2, cf4 (cladosporium), (septoria), (early blight), (bacterial spot), (bacterial wilt), (other viral tolerance, tylc, etc)
9 - Heavy production - I have a line derived from a cross of Big Beef X Eva Purple Ball that will be the model
10 - Widely adapted - Must be capable of growing and producing over most of the U.S. and Canada


Some nice to have traits would include ability to set fruit even at temps over 100°.

I will have to evaluate plant form to determine which makes the most sense. I have seed of varieties with indeterminate, determinate, dwarf rugose, ultra dwarf, and brachytic plant habit.


Varieties I plan on growing to see what can be done:
Kimberly X Eva Purple Ball - to move the precocious flowering gene into a larger fruited variety
(BBxEPB) X LA4026 to combine jointless, high lycopene, F1, F2, F3
LA4454 X Druzba to combine the sucr gene with a good flavored line
Tastiheart X LA2006 to combine cold tolerance with fruit set at 40°F
Perth Pride X (disease tolerant breeding line from R. Gardner) to get ph3 into a dwarf
Doublerich X LA0722 to move the ascorbic acid gene(s) into a high vitamin A line

I'll have to work on this more later. The above is a preliminary outline and will have to be adjusted to fit circumstances later.

I would love comments of other traits you think are important or critique of the above plans

DarJones
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