Frost Tolerance in Melons

[Joseph Lofthouse]

The Keen101 watermelon proto-landrace has produced two plants with melons that looked like this today:


I harvested one watermelon from my proto-landrace. It is super ripe. I have been anxious all day to open it, but I gotta keep my priorities straight... Can't open it until I can take a picture, and can't take a picture until daylight.

[keen101 (Biolumo / Andrew B.)]

..interesting... I don't recognize that kind from growing in my garden last year... perhaps it is a unique f1 hybrid..

EDIT:
It looks closest to this one, which was arguably the biggest and the one that did the best last year. I suspected it was a sugar baby, lots of brown seeds. Judging from the photos mine was more of a round bowling ball shape, while Josephs looks like it could be a hybrid.

[Joseph Lofthouse]

Yesterday, I harvested my first diploid watermelon for the season. It looked like this:

[terracotta]

On closer examination... On the top surface: The green leaf has a moderate number of leaf hairs that are about 3 mm long. The silver leaf has a huge number of leaf bumps densely packed, but they are only about 0.2 mm long, more like bristles than hairs. The hairs/bumps are white, but they are not primarily responsible for the appearance of the leaf.

On the bottom surface: The silver leaf is like scales. The green leaf is much smoother. The longest hairs on the silver leaf are about 0.5 mm long on the ribs. The corresponding hairs on the green leaf are around 3-4 mm long.

The silver color can be rubbed off with light pressure, but it doesn't blow off.

The alleged tetraploid Charleston Gray are even more hairy... What tremendous luck!!! To convert the one cultivar that is the most unlike anything else that is available? An experiment for next year would be to grow some commercial Charleston Gray and see if it has hairy leaves... How about it. Anyone growing Charleston Gray? What do the leafs look like?

I looked it up the silvery stuff is due to thrip damage.

Are you going to convert the most cold hardy/frost tolerant melon into a tetraploid?

Are you going to plant some seeds to overwinter?

[Joseph Lofthouse]

Sept 10, 2012 11:13:29 GMT -5 @terracotta said:

Are you going to convert the most cold hardy/frost tolerant melon into a tetraploid?

Are you going to plant some seeds to overwinter?

I intend to (attempt to) convert some of the melons into tetraploids. And then grow them as a jumbled up landrace.

Among the plants targeted for conversion are:

• 2-3 of the plants with the largest leaves.
  
• A few of the earliest melons to produce fruit.
  
• The most productive cultivar based on yield has already been converted.
  
• At least 1 plant with each available fruit color (so far that's coral red and light yellow).
  
• At least 1 plant with each available rind pattern (gray, striped).
  
• At least 1 plant with each available shape (round, oval).
  
• Anything else that is so unique that it just begs to be carried over into the tetraploid landrace.
  

Weeds were a tremendous problem with the early spring planted watermelon seeds. I may plant some in the fall into a bed containing sterilized soil, and then plan on transplanting them in early summer.

[ferdzy]

Joseph, do you have Golden Midget? I grew that this year for the first time and was kind of impressed. The flavour was ho-hum to average, but it beat the next watermelon by probably over a month AND you can tell when they are ripe very easily. I'd describe them as determinate, though, and the melons are small. Still, I'd like to try crossing them with other things and see what happens.

[Joseph Lofthouse]

Sept 10, 2012 14:22:06 GMT -5 ferdzy said:

Joseph, do you have Golden Midget?

I planted seeds this spring. Still don't know for sure if they grew.

[ferdzy]

Huh. If you don't know, then they probably didn't. Because they are so distinctively yellow, and the yellow starts showing up quite early. That's too bad. I'd have thought they were a contender for sure.

[Joseph Lofthouse]

Sept 10, 2012 17:59:14 GMT -5 ferdzy said:

Huh. If you don't know, then they probably didn't. Because they are so distinctively yellow, and the yellow starts showing up quite early. That's too bad. I'd have thought they were a contender for sure.

I'll take a closer look this week.

I am growing a 300 foot long row of watermelons divided among 4 separate patches. Many of them have not produced fruits yet. Even if they have fruited, I might only look closely at any particular watermelon patch once every week or two. (I am growing 50,000 row feet of other crops.) A while ago after sunset but before total dark, I noticed a palish fruit that looked similar to Charleston Gray but was definitely not. I'm thinking that might turn out to be a golden midget. My sunglasses are blue-blockers, so during the day, everything looks golden anyway.

Early fruiting wouldn't be particularly noticeable in my garden, my collaborators and I have screened hundreds of named cultivars and thousands of new F1 hybrids looking for earlier melons.

I downloaded photos of immature golden midget fruits. I'll go find the possible candidate again and let you know.

[ferdzy]

Ah, okay! Hope so.

[YoungAllotmenteer]

Joseph,

I would be curious to get some more detail about your climate (given the 100 frost free days). I have tried, and failed to grow Watermelon previously with 365 frost free days, and now in the UK we probably have something like 210 frost free days, but given the low average temperatures (~18C / 65F) I still couldn't grow Watermelon.

I assume your climate is hot from the word go when the frosts stop, and is hot until the frosts start again?

[Joseph Lofthouse]

Sept 11, 2012 1:16:26 GMT -5 YoungAllotmenteer said:

I would be curious to get some more detail about your climate (given the 100 frost free days). I have tried, and failed to grow Watermelon previously with 365 frost free days, and now in the UK we probably have something like 210 frost free days, but given the low average temperatures (~18C / 65F) I still couldn't grow Watermelon.

I assume your climate is hot from the word go when the frosts stop, and is hot until the frosts start again?

This year, my watermelon growing season was pretty much 85 to 90 F during the day, and 55 to 60 F at night during July, and August. No rain or dew. Once a week sprinkle irrigation for 12 hours. The watermelons received frost approximately 10 times during June after they germinated and before it got warm enough for them to grow. Our last frost was on June 20th, the summer solstice.

Here are some graphs on the same scale [Courtesy of wunderground.com] for the weather this past June in London and in my garden.

London, June 2012:


Joseph's Garden, June 2012:


I would describe my climate as extreme... Daily temperature swings of 40 F are typical, with swings of 50 F fairly common. (Due to the high altitude and dry climate, I have intense sunlight during the day, and dramatic radiant cooling at night.) So I might have a high of 85 in the day and frost at night. In London temperature swings of 20 F between night and day are typical, and it is fairly common for the high and low temperature for the day to be within a couple degrees of each other.

My dew point can be as much as 70 F below the current temperature, and even at night it is often 10 to 20 F below. In June 2012, London had dew about 24 days. I had dew/frost about 8 days.

London had a good soaking rain on 14 days. I had good rains on 3 days and that's during my rainy season!!!!

While you may carry a slicker or an umbrella, I carry a parka in my vehicle all year long, because I know that I am going to want it at night, even during the hottest days of August.

Watermelon requires about 900 GDD:13C in my garden to produce the first ripe fruit. [Growing degree days in which the average daily temperature is higher than 13 C.) There is not that much heat available in London during a growing season. That's not saying that watermelon couldn't be grown in London, just that they would need a warmer micro-climate, or genetics that allowed it to thrive in cooler average temperatures. I am selecting for desert conditions with extreme temperature differences and exceedingly low humidity. Perhaps there are other growers that are selecting for maritime conditions.

[richardw]

I'm amazed just how low your dew points are Joseph

[Joseph Lofthouse]

Sept 11, 2012 14:23:19 GMT -5 richardw said:

I'm amazed just how low your dew points are Joseph

Yup. I'm always scheming inventions for passively extracting drinking water out of the air... But I always run into the problem, due to the low dew points, of extracting it as ice, which causes it's own set of engineering problems to be overcome in addition to achieving low enough temperatures. I've come up with plenty of easily achieved techniques that would work with higher dew points.

[keen101 (Biolumo / Andrew B.)]

Sept 11, 2012 14:58:36 GMT -5 Joseph Lofthouse said:

Yup. I'm always scheming inventions for passively extracting drinking water out of the air... But I always run into the problem, due to the low dew points, of extracting it as ice, which causes it's own set of engineering problems to be overcome in addition to achieving low enough temperatures. I've come up with plenty of easily achieved techniques that would work with higher dew points.

Hmm... an interesting topic that might be worth starting another thread about it. The idea of Atmospheric Condensers are always an interest to me. I had always assumed one would need electricity to build one though. The idea in my head was something akin to a modified refrigerator to act as a cooling device and some tubes somewhat like in distillation, being run by a battery being charged by solar panels.