Re: Light for Pumpkins


In a message dated 3/25/99 10:08:34 PM Eastern Standard Time,
jpritchard@mindspring.com writes:

<< 
     I live in Columbus, OH.  The 40th parallel passes directly through the
 middle of the city.  I was wondering about day length and heat having an
 effect on pumpkin size.  It seems that the really big pumpkins are grown at
 least 41 degrees and 30 min N.
 
     There is a major difference on how many hours of sunlight I get compared
 with growers in Canada and the New England states,  especially when you look
 at it from a per season perspective.  Have there been any growers who use
 artificial light on their best plant for to mimic light conditions in the
 northern growing areas fool the plant into thinking the day is longer?   It
 might work if you only used the artificial light for a short period  at the
 beginning and end of each day.  Any thoughts?
 
     Also, I know pumpkins are heat lovers.  Does the growth slow
 dramatically at a certain temperature?  If it does, this might be another
 area to look.   Because in Ohio we can get some brutally hot days in the mid
 to upper 90's that may last 2 weeks.
 
 John J. Pritchard
  >>
John,
   The length of day difference is just a matter of minutes in July and Aug.
between 41 and 43 degrees. I think the big problem is the brutal heat. An 80
degree day and a 60 degree night that they get up North is better. A newly
pollinated pumpkin will abort in 90 degree heat......if it kills a pumpkin
baby, the adult pumpkins can't be thrilled with it either. I remember reading
many moons ago, that the respiration rate ofa plant can double with every
10degree C increase in temperature. If it is 90 or 100 during the day and the
plant wilts and photosynthesis shuts down, you make less food. Then follow it
with a hot night of 75 degrees and that poor pumpkin is on a respiration
treadmill......using up more food at night with the higher temps. Cornell has
done pumpkin yield studies vs. latitude.....I don't remember the exact
numbers, but it was something like this. New York State 20 tons per acre. Mid
Atlantic states 7 tons, down South 1 ton per acre of field pumpkins. Note: I
know John knows, but for the rest of the readers......respiration and
photorespiration is kind of like the calorie burning in our bodies. The higher
the respiration rate, the more food burned up.
pumkinguy

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