Re: how to prevent leaves from wilting
- To: pumpkins@mallorn.com
- Subject: Re: how to prevent leaves from wilting
- From: P* <P*@aol.com>
- Date: Thu, 19 Mar 1998 08:22:32 EST
Dan,
There is a light compensation point for every plant ( I don't know what it
is for an Atlantic Giant). Light levels above a certain amount of illumination
produces no more photosynthetic response, so if you constructed a partial
shading lattice that produced shade and cooling but still allowed the optimum
amount of light...you would be gaining. When a leaf is totally wilted for
whatever reason, photosynthesis is not taking place or is taking place at a
reduced rate. The flip side of the coin is........lets say that you have a
lattice set up and it is optimum on a bright sunny day, what happens on a
cloudy or partly cloudy day. Levels will be lower than optimum. Heat causes
wilting even when adequate moisture is in the soil. You could have rain all
night and follow it with a 100 degree day and the plants will wilt. The other
bad thing with temperature is increased respiration and photorespiration in
the plant. Respiration and photorespiration(during the day) is the calorie
burning process in a plant. For every 10 degree C increase in temperature,
respiration rates double (roughly). So the hotter it is, the more food the
plant consumes just to sustain itself. Food is made by the plant during the
day and is consumed by the plant both day and night. Net photosynthate (food)
gains would be the amount made during the day minus what is used up during the
day minus what is used up during the night. If your plant is shaded to the
point where you only get 80% of the photosynthesis and then the plant is
burning calories rapidly because it is 95 degrees in the shade....you get less
of a net food gain. Don't forget also that the plant burns calories faster on
a hot night. For the southern growers, pulling a shade cloth over your plant
will increase temps on a sunny day so that is not the answer. If you have
partial shade that is up, off the plant with air circulation under it, you
will be better. Intermittent water sprays are great for the plant. Evaporative
cooling takes place and the wilt will stop. You must allow enough time in
between sprays for the plant to dry out so disease is not a problem. You may
be able to construct a lattice high enough so the sun hits the plant in early
morning and late afternoon when things are cooler. Just have the shading in
the Maximum heat of the day when the sun is overhead. Where I am in
Connecticut it is hot with no lake effect cooling and too far from the ocean.
But I am not as hot as Atlanta or Texas. I use overhead spraying and the
plants don't wilt. My nights are still a little too warm but I don't want to
water all night, every night for possible disease problems. A 400 pound
pumpkin in Texas might be a greater accomplishment than a 700 pounder up
North.
pumkinguy@aol.com
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