[Arid_gardener] Question from Home-Hort WWW page

[Dick Gross]

I think it is called Latent Heat of Evaporation but we don't especially want evaporative cooling when our saltload is typically 8.5 wt. percent in our water. But, whatever you can make work for you, Richard, is okay, surely.

Dick
  ----- Original Message ----- 
  From: Richard Short 
  To: Dick Gross 
  Sent: Tuesday, December 05, 2006 8:40 PM
  Subject: Re: [Arid_gardener] Question from Home-Hort WWW page


  Dick,

  Thanks for the information. I was hoping that there might be some varieties who's pollen didn't burn at 100+. 

  I guess I'll concentrate on getting plants in early so they can set fruit before the temperature rises too much. 

  I do have a second experiment that I ran last summer using misters and a 5 foot high wall around the garden to contain the heavy cold air. That allowed me to keep that garden significantly cooler, but I don't have the process fully worked out yet. When the tomatoes grew in that area, the temperature dropped further, probably due the added vegetation reducing the heat load. When the monsoons hit, all the fruit cracked and got some kind of fungus. The process needs more work. 

  Thanks for your reply,
  Rich

  ----- Original Message ----- 
    From: Dick Gross 
    To: rm.short at att.net 
    Sent: Tuesday, December 05, 2006 7:14 PM
    Subject: Re: [Arid_gardener] Question from Home-Hort WWW page


    My experience has been that one may still get a few fruit to set and mature at 100 plus Fahrenheit but the pollen is believed to be dead at about that temperature. It doesn't have to experience direct sun; that temp in the shade may kill the pollen as readily but shade may keep the temperature below the fatal point. That statistic may not be absolute. The plant itself will grow vegetatively and bloom like crazy but dead polen isn't capable of fertilization. Fruit already set will usually develop normally regardless of how hot it gets but fast growth from ambient temperature, excess fertilizing and irrigation may exceed the skin's ability to expand as fast as the growth rate and splitting may result. 

    Any fruit set before those critical factors are reached will usually mature normally even if some splitting has occurred. The trick is, I believe, to get the tomato vine vigorously growing and blooming as soon after the last frost as possible to get most of the pollination accomplished before ambient reaches 100F at which time shade may keep some pollen alive for a few more days. This may just be my imagination, but it seems to me that cherry tomatoes do better in heat. I don't believe there are any significant variables between varieties' abilities to set in the heat

    But, if pollination is stopped dead the minute it reaches 100F, there will be a few tiny fruit and some nearly mature, or almost so, on the vine. These may develop normally and you may not notice a dramatic drop in production if new blossoms are pollenated after the temp drops again. 

    Keep in mind that tomatoes, as with any fruit, require full sun to produce fully and any unecessary shade will will exact a price except that a modest reduction in sun may be too subtle to notice.

    Dick Gross, Master Gardener Vlounteer
    University of Arizona Maricopa County Cooperative Extension 
    ----- Original Message ----- 
    From: <rm.short at att.net>
    To: <arid_gardener at Ag.arizona.edu>
    Sent: Monday, December 04, 2006 8:00 PM
    Subject: [Arid_gardener] Question from Home-Hort WWW page


    > Rich Short
    > 85749
    > rm.short at att.net
    > 
    > I am planning another year of trying to grow tomatoes here in Tucson during the summer. I know about tomato polen burning at around 95 degrees-F. I'm looking for special varieties that don't have this problem. I've got some varities from the University of Florida that are heat tolerant, but probably not to the extent that they could tolerate the 105-110 degrees-F that we see here. Have there been any new varieties developed recently? Genetic engineering is okay with me as long as the tomato tastes good. I've been trying to find a source of tomato seed from the the native societies of North, Central, and South America, but haven't had much luck beyond Native Seed Search. Can you reccomend any sites? 
    > 
    > 
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