Cold Frames for Desert Gardening

A cold frame very similar to mine.

The cold north is where you would typically expect to find cold frames utilized in the garden.  Where it is cold they do a great job of protecting frost sensitive plants in early spring or late fall.  They can also serve as a greenhouse, warming things up so seeds germinate sooner and grow quicker.  In the south though were freezing temperatures are rarely an issue I know of only a few gardeners that ever utilize clod frames.  This winter however I made a make-shift cold frame/mini greenhouse in hopes of speeding up the growth of my late start garden.  As I mentioned in a previous post, someone killed my entire garden at home and I had to start everything over again in late November.  Far too late for growing anything productively.  So out of desperation I bought some cheep clear plastic, covered the garden with it, and propped it up 12 inches or so with sticks.  It was sort of a ghetto cold frame but it worked really well.  The cold frame was entirely closed in order to trap heat inside.  This resulted in the seeds germinating very quickly compared to seeds planted at the same time without the cold frame.  Moisture was also trapped inside and I had to water the garden a fraction of the times I would have needed to if the garden wasn’t covered.  The heat and higher humidity also sped-up growth of the seedlings significantly.  The loss of a dead garden in the end of November was quickly redeemed by these simple cold frames.  I am already planning to use them next winter.  I am guessing that utilizing the cold frames earlier in November could speed up growth and increase production a lot. 

Advantages of using a cold frame in the desert or warm south

• Protection from infrequent freezing temperatures
• Moisture retention so watering needs are greatly reduced 
• Increased humidity which increases plant growth
• Increased temperature which speeds up germination and plant growth
• Overall increased productivity!

Easy Enzyme Experiment: Potato Catalase

Catalase enzyme formed the bubbles in the two tubes on the right.  The tubes contain extracts from beef muscle, kidney, and liver from left to right. 

In a post awhile back we discussed the enzyme catalase and its presence in animal tissues such as liver, kidney, and muscle.  Catalase was and is found to be extremely abundant in the liver, a reflection of the livers cleansing function.  It is also present, but much less so, in the kidneys, also a reflection cleansing function.  Muscle tissue however had no detectable catalase due to the fact that it is not a cleansing organ, waste products from the muscles are rather filtered and cleaned by the liver and kidneys.  Catalase also has been found in plants, where its presence is often mysterious.  Plants of course are not producing waste products similar to what animals produce, so why would they need catalase?  We can discover the answer partially by simply understanding the function of catalase.

This is what catalase does in general:

Hydrogen Peroxide + Catalase → Water and Oxygen

Hydrogen peroxide is a highly oxidative molecule, meaning it causes processes similar to rusting to occur.  Metals rust as they react with oxygen and oxidative molecules cause rusting to occur.  Similar “rusting” or oxidative reactions can occur in plant or animal tissues if oxidative molecules are present.  This is why anti-oxidants are such a big deal, they prevent tissue from oxidizing by getting rid of oxidizing molecules such as hydrogen peroxide.  Catalase is such an anti-oxidant molecule.  Catalase also converts reactive oxygen, which also oxidizes, into hydrogen peroxide and then into harmless water and oxygen.  (Of course I have simplified these reactions, so chemists, refrain from complaint!)  At the end of a reaction catalase is preserved and available to repeat the reaction over again with more oxidative molecules.  Amazingly, one catalase enzyme can repeat these reaction up to 40 million times in one second!

Another catalase reaction:

Reactive Oxygen + Catalase → Hydrogen Peroxide + Catalase → Water and Oxygen

In animals, such as us, oxidative molecules are most often produced through our metabolizing of food molecules.  So the presence of catalase makes sense.  Plants do not eat, so why would they need catalase?  If we study the process of photosynthesis we may come across a term called photorespiration.  Photorespiration simply is when a plant receives too much light and not enough water.  As a result, the plant can produce large amounts of hydrogen peroxide which can kill the plant.  Fortunatly, catalase prevents the accumulation of hydrogen peroxide by converting it to water and oxygen, and so saves the plant from oxidative damage.

A Simple Catalase Experiment Using Potatoes:
Some plants such as potato and spinach have very high levels of catalase, far higher they they would likely ever need to prevent photorespiration damage.  Why that is, no one seems to know. Scientists have had many ideas and have researched the question for almost 100 years but no one can figure it out.  But it makes isolating the catalase enzyme very inexpensive and easy if you want to run a simple experiment.  The following is a simple enzyme experiment anyone can run.
Materials:
Potato
Test tube or other small container
Hydrogen Peroxide

1. Cut up a potato and mash it.  Do not cook it, cooking will break down the enzyme so it won’t work.

2. Place the mashed potato in a test tube or other small container.

3.  Add hydrogen peroxide.  If there is catalase present foam should be produced.

The foam produced is a result of catalase converting hydrogen peroxide into water and oxygen, the bubbles are filled with this oxygen.  The more bubbles produced the faster catalase is carrying out this reaction, or the more catalase present.  The above would be considered the control for the experiment and simply indicated the presence of catalase in the potato.  Tests can be preformed to determine the effects of different conditions on the enzyme function.  By adding baking soda to the potato, a high pH or basic molecule, will change the pH and have an effect on how well catalase functions.  To another test tube, add vinegar to the potato which will lower the pH, making it acidic also having an effect.  Also try freezing or cooking the potato before adding hydrogen peroxide to determine effects.  Remember, the more foam produced the better the catalase enzyme is working.  Less foam means it is not working as well, and no foam means it is not working at all.  Test it out and see what you find.  

Potato catalase experiment.  The boiled tube (left) produced no bubbles indicating catalase has been degraded by the heat.  Room temperature tube (middle) produced the most bubbles indicating catalase is highly functional at this temperature.  The tube kept on ice (right) produced fewer bubbles indicating the lower temperature slowed down the catalase enzyme.

March Garden Economics Update

It’s been quite a while since I blogged an update on the garden.  Reason being I’ve had my frustrations and it just hasn’t been that interesting.  After planting my garden back in October I had to leave the state for several weeks and a neighborhood girl was supposed to take care of my garden.  Unfortunately, the girl didn’t do much of anything and everything died, which is rather an impressive feat.  I am still not entirely sure how she pulled that one off.  Even the onions died which I previously thought was nearly impossible.  So I had to restart everything mid to late November.  Being temperatures are quite cool in mid to late November it is not ideal for starting a garden.  Germination and growth is extremely slow, what took a week in October might take a month in November through December.  I half heartedly planted anyway, and to compensate for the lower temperatures I created a one foot tall “greenhouse” over the planted beds.  This “greenhouse” simply consisted of clear plastic sheets propped up with sticks.  Then I sort of forgot about it for several weeks.  When I finally got around to checking on it in December everything had germinated and was growing like crazy.  The small “greenhouses” had created a much warmer environment with much higher humidity.  The need for watering also decreased significantly.  By late January everything was doing extremely well, and by late February I removed the “greenhouses” due to warmer temperatures.  So what started as a huge problem, followed by a half hearted attempt at a solution, has ended in a great success story.  I may use this greenhouse idea next winter to speed up growth and decrease watering needs. 

College garden
Eggplant  2 lbs. 14oz $8.59 ($2.99/lbs.)

Tomatoes 3 lbs. 7oz. $10.28 ($2.99/lbs.)

Chard 8oz. $2.50 ($2.50/8oz.)

Radishes 1lbs. 4oz. $3.97 ($1.19/6oz. bunch)

Snap peas 1 lbs. 8oz. $6.24 ($4.99/lbs.)

Cilantro 6oz. $1.98 ($0.33/oz.)
Total produce: $33.56
Total cost: $0.00
Net: -$0.18(previous months) + $33.56 = $33.38

Time: 5 hours (previous total) + 7 hours = 13 hours

Home garden
Chard 1 lbs. 6oz. $6.88 ($2.50/8oz.)

Radishes 1 lbs. 10oz. $5.16 ($1.19/6oz. bunch)

Cilantro 4oz. $1.32 ($0.33/oz.)
Snap peas 8oz. $2.50 ($4.99/lbs.)

Basil 8 oz $7.96 ($1.99/2 oz)
Total produce: $23.82
Total cost: $15.55 (for plastic and sticks to make greenhouse)
Net: $7.10 (Previous months) -$15.55 + $23.82 = $15.37
Time: 6 hours (previous total) + 8 hours = 14 hours

Rain wise, the desert is extremely dry right now.  We did have a good rain back in December but nothing significant since.  Currently the National Weather service says we are in a La Nina weather pattern, which typically means dry winter weather.  Mid March though is one of the most consistent times of the year for rainfall.  So hopefully in a few weeks we will get a good shower.  March and April also are the end of the winter cool season garden and the beginning of the summer warm season garden.  Currently we are harvesting cool season crops like snap peas, beets, onions, chard, lettuce, cilantro, and radishes.  Within the next month we will hopefully be planting corn, tomatoes, eggplant, peppers, summer squash, and okra. 

 

So everything is going pretty well at this point.  With the minimal amount of effort I have put into the garden recently I am quite excited about the results.  Things should get better from here on out.  With the weather warming production should increase considerably in the coming months.