Why is it easy to separate the cotton wool from the roots of young plants grown in cotton?

In my book it is said that if we grow Maize and Gram seeds in wet cotton, after the seeds are sprouted it is easy to separate the cotton wool from the roots of young plants.

My question is why is it comparatively harder to separate roots from soil while it is easy for cotton wool?

How to Sprout Mung Beans

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Mung bean sprouts are a common ingredient in Asian stir fries and provide a crisp, healthy addition to any meal. In the supermarket, you'll often find them labeled more generally as “bean sprouts.” There’s no need to buy them pre-sprouted, however—you can save money by sprouting them at home in as little as 2 days. Soak your mung beans overnight, then rinse and drain the growing sprouts every 12 hours until they've reached your desired length.

Growing Peppers from Seed for Beginners

Growing peppers from seed requires a certain amount of patience. The willingness to dedicate time to nurture that seedling, and care for it as it matures, can reward you with amazing fruits.

When I first started growing, I recall researching all over the web for info on how to get started. Everyone has different methods, some just too complicated for me. Peppers are easy to grow, and I keep it very simple. After several seasons of growing hot peppers, and testing many of the tips I found all over the web, I present the step by step of what has worked best for me.

I don’t have a greenhouse and I only grow a handful of different pepper plants each year, like 5 – 10. I also don’t have garden space, so all my plants grow in containers outdoors once they are ready and it’s warm enough outside. So let’s get growing!

1) When to start your seeds

Generally, you start your seeds in the winter indoors. Exactly which month you’d like to start is up to you, but November – February is a good starting point. I’ve always started my seeds in January. November and December have too much holiday travel, gift buying and work going on for me to focus on my peppers, so January works for me

2) What are the easiest peppers to grow?

If you don’t want to wait too long for germination, Capsicum Annuum’s are probably the easiest to grow. These include jalapeños, serranos, cayennes, Thai peppers, Anaheim, Hatch, poblano, many ornamentals and more. They also do better in cooler climates and germinate readily even at lower temperatures (50oF -75oF).

Chinense species, which include the super hots, habaneros, scotch bonnets, etc., tend to have slower germination times and higher soil temperature requirements (75oF-90oF).

Just keep in mind that the germination process can be slow and irregular as the degree of dormancy (or in other words, how long it takes those seeds to wake up and grow) varies considerably between species.

3) How long does it take for the seeds to sprout?

Most pepper seeds sprout in about a week at a temperature of 70-80 degrees F., but germination can be spotty depending on the variety. Super Hots can take longer to sprout, sometimes up to 6 weeks.

4) Where do I get seeds?

You can buy seeds from your local garden center, from the many online seed suppliers (a couple I like to by from are Baker Creek Heirloom Seeds and, or simply purchase your favorite peppers from your local supermarket and scrape out the seeds. Good to go.

5) I have my seeds, now what?

You are going to start your seeds indoors. Before you plant your seeds, soak them overnight in warm water. I’ve grown seeds with and without soaking, and I found the ones I soaked did a better job of sprouting. So I pop the seeds in shot glasses with warm water (shown below) overnight and then plant in the morning. Keep track of what seeds are in what glass. You will be planting 3 seeds in each ‘pod’. Only one of these three seeds will become the producing plant, so don’t get attached.

Also, just because your seeds sprout, this does not guarantee they will all survive to become healthy plants. To ensure you grow at least one strong producing plant of each variety, plant a minimum of 6 seeds or more.

Now we’re ready to get the seeds into some soil. I’ve had the best results using Jiffy peat pellets (this is the exact box I use, available from Amazon, but all of the Jiffy boxes are far cheaper from Home Depot or any other local garden shop in your area).

I’ve also tried starting my seeds in ‘seed starting’ soil in little dixie cups, but the jiffy peat pellets give me far better germination results, so I prefer them. And they come with the greenhouse dome, which is great for getting seeds to sprout quickly in a normal home environment in the winter.

So follow the instructions on the Jiffy box. You simply pour water onto the pellets and then give them some time to absorb the water. The pellets will fully expand after several minutes (shown below).

Once the pellets are ready, pull back the mesh on the top and dig about a 1/4″ deep hole. Place 3 of the same seeds into the soil and very loosely cover with soil. Don’t pat down the soil. You want to make it as easy as possible for the seedlings to breakthrough.

Additional Soil Boosters:

Myco Blast is a soil additive I use at this point. I add Myco Blast to the seed pods right after planting the seeds and water once a week with it until the first set of true leaves appear. Myco Blast naturally enriches the soil producing stronger healthier seedlings. It is also used when transplanting.

Chile seeds require moisture and warmth to break their dormancy (meaning sprout). Dormancy is the seeds built-in survival mechanism which prevents seeds from germinating in cold conditions which would kill the young seedlings. Just be aware that the germination process can be slow and irregular as the degree of dormancy varies considerably between species. I place my seed trays on a Seedling Heat Mat to help with the germination process. It warms up the soil and I’ve found that my plants sprout far faster with the use of a heating mat.

Once the first seeds start to sprout remove the greenhouse dome and start to make sure the seedlings have enough sunlight. I keep my seedlings under a well-lit window all day, but since they sprouted in the winter months (providing fewer daylight hours) I add a very simple grow light which I turn on once the sun goes down or if it’s a cloudy day. The one I have is LED and doesn’t produce any heat, so you can put it pretty close. This year my light is about 6″-7″ above the seedlings. I turn off the grow light around 8-9 pm. Spritz the seedlings with water if the soil starts to turn a light brown. Keep them moist, but not wet.

What next happens is the survival of the fittest! You planted 3 seeds in each pod. Only one of those sprouts will move one to the next round. Your seeds will start to sprout. In each pod, you may notice one sprout doing better than the others. After the seedlings get about 2 inches, you should see the strongest sprout. You must select the strongest sprout and trim the others to let the strongest seed grow.

Now sometimes it might not be super clear on which is the strongest. I’ve had that happen. Check out the image below. You can see the obvious winner in the right pod, but all look fairly equal in the left pod. For the left pod, go ahead and pick your favorite, because they are all strong, but only one can take up that space. Trim 2, leaving only one sprout to move on. If you are VERY gentle, you can try to separate all 3 of the strong sprouts for planting separately, just try not to damage their delicate roots.

The first leaves that sprout from the seed are the cotyledons (an embryonic leaf in seed-bearing plants, the first leaves to appear from a germinating seed.)

The next set of leaves that will develop are called their ‘true leaves’. I transplant each into larger cups once they are about 3″ with their first set of true leaves.

I use plastic cups at this point. Poke 1-2 drainage holes into the bottom of each cup with an awl or screwdriver. Fill each cup with potting mix. Dig a hole that will fit the root ball. If your seedlings are in peat pots (as shown above), remove the entire peat pot mesh lining, and then place the root ball into the newly dug hole. Be careful not to disturb the roots or damage the seedling. Cover as much of the stem to promote more root growth. I plant mine lower in the cup, so the very top of the plant is about 1/2″ below the cup top so it is protected from the elements once I start hardening off.

What kind of potting soil (or potting mix) do I use?

It is important to know the difference between potting mix (also called potting soil) and garden soil. Potting mix is specially formulated for use in containers. It contains ingredients like bark and peat moss that ensure good drainage and airflow for strong root growth in containers.

If your pepper plants are going into a container, use potting mix. If they are being planted in a garden, use garden soil. I typically use Kellogg Patio Plus found at Home Depot since my peppers are grown in containers.

Time to talk about fertilizing.

After the first set of true leaves appear, this is also the point you can start fertilizing. Start using a diluted amount of fish emulsion or fish and kelp fertilizer (this is what I grab from Home Depot) to promote growth. Read the instructions on the container and then use 1/4 strength when you water your plants. I know some people don’t like the smell of a fish fertilizer (I don’t think it’s bad at all), so feel free to use whatever fertilizer you prefer.

*Note: if you have dogs that love the smell of dead things, as mine do, you may need to keep the plants out of their reach when fertilizing with fish fertilizer. If I spill even a drop, my dogs will try to lick it up because it’s fishy smelling. They’ve stopped trying to dig in the plants after fertilizing, but the first time they smelled it, they wouldn’t let go of trying to find the source of the smell in my pots.

Foliar feeding:

After your plants have three or four sets of true leaves, you can apply magnesium sulfate (Epsom salt) directly to the leaves and stem. Epsom salt keeps the plant foliage strong and prevents light green to yellow leaves from developing.

Make sure that the Epsom salt you use does not have any additions such as scents.

Add a 1 teaspoon Epsom salt to a gallon of water and shake it up well. Pour the mixture into a spray bottle and then spritz the leaves and stems with the solution until thoroughly covered. Spray your plants every other week so that one week you water with fish emulsion, and the other week you give your plants the foliar feeding.

Additional Soil Boosters:

There are a couple of other soil additives I use. The first is Myco Blast. I add Myco Blast to the seed pods right after planting once a week until the first set of true leaves appear (then switch to regular fertilizer). Also, add Myco Blast to the soil when transplanting to naturally enrich the soil.

The second one I use is Soil Blast. Water with the Soil Blast and tap water solution once every week. It establishes beneficial bacteria necessary for excellent soil and strong plants.

For the next month+ you’ll watch your plants grow. Water, fertilize and keep them healthy. During this time I start to harden off my plants. This is a key step in the survival of your plants. Don’t skip it.

What is hardening off and when do I start?

Your plants have been in a controlled indoor climate, with no wind, extreme sunshine or cold nights to deal with. Hardening off is the process of gradually allowing your young plants to slowly get used to outdoor conditions.

The process takes a couple of weeks, so start a couple of weeks before you plan to transplant them outdoors. And this is not a strict schedule. You just want to get the plants outdoors for longer and longer periods each day, but keep an eye on them and make sure they don’t start to wilt. Also don’t set them out on very windy days. Keep in mind the soil will dry faster outdoors due to sun and wind so water more frequently.

Here is a basic schedule to start with: Set them outdoors the first day for 1/2 hour in just partial sunlight in an area protected from the wind. After your plants are outdoors for 1/2 hour somewhat protected increase the time daily to 1 hour, 2, 3, 4, leading up to 8 hours per day. Then leave them out overnight for a full day (as long as there is no threat of frost).

When is a good time to transplant your plants?

Plants should be 6-10 weeks old with dark green color, thick stems, and no blooms. Pinch off any blooms so the plant will put energy into adjustment after transplant. Wait until the last frost date for your zone has passed and nighttime temperatures are above 50° F, and your seedlings are hardened. Peppers are warm-season crops that grow best at temperatures of 70-80° F during the day and 60-70° during the night.

Transplanting time!

Once your plants are adjusted to being outdoors, it’s time to move them to their permanent home. All of my peppers plants go into pots outdoors. I’ve used a few different containers regular pots, home depot buckets, the EarthBox, and the City Pickers raised garden bed kits. If your local garden center has these in stock, they are typically much less expensive in-store.

My personal preference is the EarthBox. The EarthBox is better made than the City Pickers box. They are very similar, but a couple of the wheels snapped off on my City Picker Box first year, and my EarthBox, which I’ve had longer, is still going strong. Here’s more info on how the EarthBox works. My plants just do better in the EarthBox compared to any other pot. Plus it comes with organic fertilizer, dolomite, mulch covers and a detailed set of instructions explaining exactly how to plant your plants using their system. It’s just simple and I like simple.

I will typically plant 4 pepper plants (and not necessarily the same type of pepper) in one EarthBox. I use the EarthBox for plants that tend to grow larger. Also, if you have access to compost, certainly mix that in with your soil.

I do use regular pots for smaller pepper plants. If I’m growing something small and compact, like ornamental Thai peppers, those do fine in small pots. Here’s some I grew in a small pot.

Note on reusing pots from year to year:
If you are reusing pots, which is fine, your previously used pots need to be sterilized to kill any organisms that may spread disease to next year’s plants. Once emptied and washed out, pots should be soaked in a solution of 1 part household bleach and 9 parts water for about 10-20 minutes, and then rinsed and soaked in clean water to remove any bleach residue that remains.

Once you’ve chosen what your plants are going into, it’s time to move them. I use the same type of potting mix as the first time I transplanted them, an organic potting mix (for containers) that says it’s good for peppers & tomatoes. These soils typically have a mix of peat moss, some sort of bark, perlite, & dolomitic limestone. Peppers like well-draining soils.

Dig a hole for each plant that is a bit larger than the root ball of the plant. Hold the plant by the rootball (not the stem) and place it in the hole. Take care not to disturb your plant’s roots during transplant. Set the plants slightly deeper (up to an inch) than they were grown in the container.

You will need to water plants more frequently than was necessary indoors.

In addition to shallow roots, peppers have fairly brittle branches that eventually grow heavy with peppers. Some plants benefit from staking (insert a stake into the soil and tie your plant to the stake) or caging. I do stake many of my pepper plants to give them added support once they start growing taller.

And there you go. Fertilize and water on a regular schedule and enjoy the fruits of your labor!

Common problems you may have:

Tall ‘leggy’ seedlings:

‘Leggy’ seedlings typically have stretched skinny stems and look fragile. They may start bending forward rather than growing up straight with a strong stem. The most common issue here is not enough light. The young seedlings are struggling to access adequate light from any source they can. I would suggest using a grow light placed fairly close (6” – 8”) from the seedlings.

This is a result of too much moisture and is a common white mold you find on top of potting soil. Let them dry a little. You can run a fan at the plants to slow the mold growth down and strengthen the stalks of the plants at the same time. If it’s still sticking around, You can also simply scrape it off. This happens to me a lot and it’s never harmed my seedlings.

Gnats around your indoor pepper plants:

Gnats love moisture and are attracted to fruits, so it’s no surprise that they often infest kitchens. I have several fruit trees in the backyard so gnats always find their way into the house and love to hang out on my pepper plants while they are growing indoors.

My simple solution to get rid of these little pests is to set up a vinegar trap. Gnats find the scent of apple cider vinegar very attractive (and wine… I’m always trying to keep them out of my wine glass). So I just set a small glass of apple cider vinegar in the middle of my plants and they wind up in the glass. Typically that’s enough for me, but if you have a good amount of gnats you can set up a larger trap in a Mason jar. Put apple cider vinegar into the jar, like the bottom 3 inches should be good. Pop several holes in the jar lid then cover the jar. You could also use plastic wrap with holes to cover the jar. The gnats will enter the jar via the holes on the lid and get trapped in the vinegar solution.

Soaking up oil spills — with cotton

Texas Tech researchers show how well raw cotton (right) absorbs and holds oil (left).

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September 4, 2014 at 7:40 am

Crude oil is still washing ashore more than four years after the BP Deepwater Horizon accident spilled more than 200 million gallons of this petroleum into the Gulf of Mexico. Fisheries, wildlife and ecosystems could suffer for decades. Now help for cleaning up such disasters comes from a crop people have grown for thousands of years: cotton. But this material is a lot different from the fabric in your favorite tee shirt.

To work well on oil spills, the substance used to pick up the mess — a sorbent — should sop up oil but not water. Cotton in its natural form has a waxy coating. As such, it will “absorb oil and repel water,” explains Seshadri Ramkumar. He’s a materials scientist at Texas Tech University in Lubbock.

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Just throwing a huge wad of cotton onto a spill isn’t enough, however. Cotton soaks up oil best when it can use three processes at once. In the first — adsorption — oil clings to the surface of the cotton fibers. The fibers may also absorb oil, bringing it inside the fibers. (That’s the same process by which plant roots take up water from the soil.)

Finally, cotton can soak up oil by letting it flow into channel-like spaces that form between its fibers. This last process is known as capillary action. It’s the process by which blood flows into a narrow tube when a nurse pricks your finger for a sample. The tiny spaces between cotton fibers can act like those blood tubes. But in natural cotton, oil can’t get far because the fibers are tangled.

The Deepwater Horizon well spilled more than 200 million gallons of crude oil into the Gulf of Mexico in 2010. This aerial photo of oil floating on the water surface was taken roughly three weeks after the spill began. National Oceanic and Atmospheric Administration To untangle them, the researchers card — or comb — the cotton. A carding machine has a cylinder with rows and rows of tiny prongs. The machine pulls the fibers straight so that they all go in the same direction. “It’s just like you’re combing your hair,” explains Vinitkumar Singh. A graduate student at Texas Tech, he also worked on this project.

The researchers stacked up layer after layer of carded cotton. “Everything is in the same direction,” Ramkumar explains. Together, these layers make a batting. It’s similar to the batting used to fill the inside of a quilt. But instead of being stitched or pressed tightly down, the batting for cleaning up oil must stay loose.

Friction between the layers makes them cling loosely together. “It is not a very strong bond,” says Singh. That looseness creates lots of channels into which oil can flow and collect.

When combined, the three sopping processes let cotton soak up oil quite well. And low-grade cotton that’s not mature works about 7 percent better than high-quality mature cotton. The reason: Immature cotton has more wax. Thus, it repels water better. Those young fibers also are finer. That gives them a relatively bigger surface area for adsorption and to form channels for capillary action.

In lab tests, the low-grade cotton batting absorbed 50 times its weight in oil. That’s better than what many plastic materials do. And unlike plastics, cotton decomposes naturally when it can’t be used any more. Ramkumar and his colleagues at Texas Tech and Cotton Incorporated in Cary, N.C., reported their findings in the July 30 Industrial & Engineering Chemistry Research.

/>Texas Tech researchers take batting made from raw cotton (top) and lay it atop spilled oil floating on water. When they remove it again (bottom), the oil has left the water and now clings to the batting. Texas Tech University Other advantages — and questions

“Cotton is also easy to remove once it’s done its job,” Ramkumar told Science News for Students. Oil-soaked batting will float on water. That’s because it has a lower specific density than water. With less mass than the same volume of water, this oil helps keep the cotton batting afloat.

Using low-grade cotton for oil clean-ups also could bring farmers more money when crops don’t mature due to drought or other problems. Roughly one-fifth of the cotton grown in Texas, for instance, falls into the low-grade category, Ramkumar says. It usually sells for less money because immature cotton has less cellulose. Fabric mills that make clothing don’t want it because this kind of cotton doesn’t handle dyes well. But what makes a poor cotton for clothing may prove a superior type for oil clean-ups.

The novel structure of the batting might help it sop up oil better, says Paul Sawhney. He’s a textile scientist with the U.S. Agricultural Research Service in New Orleans, La.

But as a cleanup tool, what also will matter is how the batting holds up, Sawhney notes. “Once the oil is in there, you’re talking about 50 times more weight,” he points out. The batting needs to hold that liquid in. And the batting should stay intact when it’s moved and eventually lifted up for removal.

Field tests can explore different ways to ensure that. Lightly needlepunching or stitching the batting’s layers together might help, Sawhney says. Encasing the batting in an expandable web is another idea.

But that’s how science works. Each advance suggests more questions to explore.

Sadly, spills happen. Indeed, hundreds of gallons of motor oil and hydraulic fluid spilled into the Grand River in Michigan earlier this year. A ship collision spilled oil into the Mississippi River last month. And some 9,000 gallons of diesel fuel spilled into the Ohio River from a power plant near Cincinnati. Accidents can be limited — but never completely prevented. That’s why having cleanup tools at hand is important — especially simple, inexpensive and high-performing options, such as raw-cotton batting might offer.

Power Words

absorption The process by which a fluid penetrates another material, such as crystals or fibers. Liquids and nutrients enter plant roots through absorption.

adsorption The process by which a substance sticks to, or adheres, to the outer surface of another material. Sunscreen stays on your skin because of adsorption.

batting In textile science, a lofty material, usually nonwoven, such as the filling between quilt layers. In baseball, the act of swinging a machine-tooled stick with hopes of hitting a ball.

capillary action The force that governs the movement of a liquid along the surface of a solid. Because molecules of the liquid are attracted to the surface and to each other, they can pull each other along. Capillary action explains how sponges wick up liquids.

cellulose A type of fiber found in plant cell walls. It is formed by chains of glucose molecules.

chemistry The field of science that deals with the composition, structure and properties of substances and how they interact with one another. Chemists use this knowledge to study unfamiliar substances, to reproduce large quantities of useful substances or to design and create new and useful substances.

crude oil Petroleum in the form that it comes out of the ground.

ecosystem A group of interacting living organisms — including microorganisms, plants and animals — and their physical environment within a particular climate. Examples include tropical reefs, rainforests, alpine meadows and polar tundra.

engineering The field of research that uses math and science to solve practical problems.

friction The resistance that one surface or object encounters when moving over or through another.

materials science The study of how the atomic and molecular structure of a material is related to its overall properties. Materials scientists can design new materials or analyze existing ones. Their analyses of a material’s overall properties (such as density, strength and melting point) can help engineers and other researchers select materials that best suited to a new application.

needlepunching Perforating layers of fibers to hold them together or make a design.

plastic Any of a series of materials that are easily deformable or synthetic materials that have been made from polymers (long strings of some building-block molecule) that tend to be lightweight, inexpensive and resistant to degradation.

specific density A measure of mass per unit of volume. The specific density of water is usually 1 gram per cubic centimeter.

textile Cloth or fabric, which can be woven or nonwoven.


S. Perkins. “Cool jobs: Repellent chemistry.” Science News for Students, September 17, 2013.

S. Ornes. “‘Self-cleaning clothes.” Science News for Students, January 10, 2012.

S. Ornes. “Gulf oil finds many paths.” Science News for Students, September 10, 2010.

S. Ornes. “The oily Gulf.” Science News for Students, June 2, 2010.

Original Journal Source: V. Singh et al. “Novel natural sorbent for oil spill cleanup.” Vol. 53, Industrial and Engineering Chemistry Research, Vol. 53, July 30, 2014, p. 11954. doi: 10.1021/ ie5019436.

About Kathiann Kowalski

Kathiann Kowalski reports on all sorts of cutting-edge science. Previously, she practiced law with a large firm. Kathi enjoys hiking, sewing and reading. She also enjoys travel, especially family adventures and beach trips.

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Seed museum

Create a collection of seeds from different types of fruits and vegetable.

  • Paper towels
  • Large glass jar
  • At least two packets of different fast-sprouting seeds (such as lima beans, zucchini, radish, sunflower, zinnia, radish, lettuce, marigold, chives or basil)
  • Glass marking pencil
  • Aluminum foil
  1. Use the glass marking pencil to make lines on the outside of the jar and label separate areas for each of your seed types.
  2. Moisten the paper towels with enough water to make them damp, but not sopping wet. Line the inside of the jar with the moistened paper towels.
  3. Carefully insert each type of seed between the layer of damp toweling and the side of the glass jar. Put the seeds about an inch below the top of the jar. You should be able to observe the seeds through the glass.
  4. Cover the outside of the jar with aluminum foil and keep the jar in a warm, protected place.
  5. Every day, remove the foil and observe the seeds. Keep the paper towels moist, and replace the foil after your observations.
  6. Compare the ways in which the different types of seeds sprout.

For younger children, use one type of seed (I suggest the lima beans, as they are large enough for little hands to grasp easily). Instead of a jar, put the seeds and paper towels into plastic bags with a zip closure. Leave a small corner of the top open for air circulation. Prepare three seed bags. Place one in the refrigerator tape one to the inside of a sunny window, and put one on a shelf inside the room. Ask the children to predict which seeds will sprout first. Talk about the conditions that seeds need for germination.

Materials Needed for the Germinating Seeds in a Bag Experiment:

Or use this great growing window from Learning Resources:

Extend the Activity with Books About Gardening for Kids

You don’t have to purchase sees specifically for planting for this experiment. We used beans sold in the grocery store for human consumption for our seeds in a bag, and they sprouted right up with any problems at all!

Before starting the experiment, soak your bean seeds overnight in water. This will sort of “wake up” the seeds and get them ready to germinate. You’ll get faster results if you pre-soak your bean seeds this way. Drain the seeds before placing them in the bag.

Dampen a paper towel and fold it into the bag.

Place the seeds along one side of the bag, pressing them against the paper towel. Seal the bag tightly, and hang in a window using tape.

Make sure the beans are visible on the side of the window where the kids will be observing their seeds sprout.

Wait 24 hours. You should be able to see the seeds start to pop open and sprout after this time.

Within 3 days to a week, you’ll have fully sprouted seeds!

In a few more days, you’ll see the leaves start to emerge.

At this point, your beans are ready to move to soil. Plant them in a rainboot garden, or another small planter and watch them continue to grow!

More Garden Theme Toys for Kids:

More Activities You’ll Love!

Top 16 Experiments on Respiration in Plants (With Diagram)

The following points highlight the top sixteen experiments on respiration in plants. Some of the experiments are: 1. Demonstration of Aerobic Respiration in Plants 2. Demonstration of Anaerobic Respiration 3. Demonstration of Alcoholic Fermentation 4. Determination of Rate of Respiration 5. Comparison of Rate of Respiration in different Plant Parts and Others.

Experiment # 1

Demonstration of Aerobic Respiration in Plants:

Aerobic respiration in plants can be experimentally proved with the help of a simple apparatus like:

(i) Respiroscope which consists essentially of a stout vertical tube which is bent into a bulb at the one end (Figure 19a), or

(ii) With the help of a long-necked round-bottomed flask fitted with a centrally-bored cork at the mouth through which passes a glass tube (Figure 19b).

The respiroscope or the inverted flask is fixed vertically to a stand and a few germinating gram seeds or flower petals are placed in the bulb of the respective or in the inverted flask plugged with cotton at the base the vertical tube of the respiroscope or inverted flask is dipped just below the surface of water or mercury in a beaker.

A few caustic potash (KOH) pellets are introduced in the bent portion of the respiroscope or in the long neck of the round bottom flask and kept in position with loosely held cotton wool Care should be taken that respiratory materials and KOH pellets do not come in contact.

Precautions should be taken that the free end of the tube does not touch the bottom of the water or mercury trough. Fittings must be air-tight to avoid any leakage.

The apparatus is allowed to stand for a few hours when it is seen that water or mercury has risen in the vertical tube of the apparatus proving the production of partial vacuum.

Due to respiration of germinating seeds or flower petals CO2 has been released which is at once absorbed by KOH pellets. Thus the partial vacuum produced by the absorption of O2 by the respiring material could not be filled up by the released CO2. Hence, water or mercury is drawn upward into the tube.

Experiment # 2

Demonstration of Anaerobic Respiration:

A few germinating gram seeds are taken in a test tube which is completely filled with mercury and is then inverted just below the surface of mercury in a trough. It is then vertically held with a clamp and stand (Figure 20).

Observation from time to time reveals that a gas is formed within the test tube by the displacement of mercury in the test tube. A few KOH pellets arc introduced through the open end of the test tube when mercury again rises filling the test tube.

Here the respiration of germinating seeds takes place in complete absence of O2 supply and the gas produced is CO2 as evidenced by its absorption by KOH. This proves that anaerobic respiration has taken place.

Experiment # 3

Demonstration of Alcoholic Fermentation:

A fermentation tube or Kuhne’s vessel (Figure 21) is filled with 10% sucrose solution and mixed with a small quantity of Baker’s yeast or a few millilitres of suspension of yeast cells. The open end of the apparatus is plugged with cotton wool.

Occurrence of fermentation or anaerobic respiration and collection of CO2 gas in the back arm of the Kuhne’s tube are observed. When the cotton wool is taken off smell of alcohol may be perceived.

In alcoholic fermentation the sugar and yeast soln. broken down to alcohol and carbon dioxide liberating certain amount of energy. The enzyme, ‘zymase complex’ present in the yeast brings about this reaction through a number of steps. Alcoholic fermentation takes place in absence of atmospheric oxygen. Hence it is an anaerobic process.

Experiment # 4

Determination of Rate of Respiration:

The rate of res­piration can be measured with the help of Ganong’s respirometer (Figure 22).

Description and Experiment:

The apparatus consists of three Levelling tube parts:

(i) The bulb for the res­piring material which ends in a 10% KOH win smaller bulb at the bottom. The bigger bulb is provided with a stopper having a lateral hole, through which atmospheric con­nection can be made by turning the stopper,

(ii) A graduated manometer fitted with the bulb, and

(iii) A levelling tube connected with the manometer tube by rubber tubing. The whole apparatus is clamped on a stand.

Two ml of respiring material (measured by displacement of water) like germinating seeds or flower petals are placed into the bigger bulb of the respirometer. A 10% solution of KOH is taken in the manometer tube. At the beginning of the experiment the air around the material is brought to the atmospheric pressure by turning the stopper of the bulb until its hole coincides with that of the neck of the bulb.

The levelling of the reservoir tube on the right is so adjusted that the KOH solution in the tube is at the 100 ml mark at the bottom of the manometer. Two ml of respiring material is now surrounded by 100 ml of air. The experiment is started by turning the glass stopper at the top and thus cutting off connection with the atmospheric air.

As the respiration takes place in a closed space, the solution in the manometer tube rises up gradually. The reading should be taken up to 80 ml mark, i.e., up to 20 ml volume (since atmospheric oxygen is 20%) at an interval of 10 minutes, each time bringing the liquid in both the tubes at the same level, i.e., the liquid in the closed tube is brought under atmospheric pressure.

Results are expressed as millilitre of CO2 evolved per minute by the given respiring material.

The released CO2, on coming in contact with KOH solution, is absorbed by it, oxygen is consumed and as a result KOH solution rises up in the manometer tube. The rate of rise of KOH solution is taken as a measure of rate of aerobic respiration in terms of volume of O2 consumed per unit time per 2 ml of respiring material.

One-fifth volume of atmos­pheric air is O2. Hence out of 100 ml of enclosed air within respirometer there is 20 ml of O2. Hence reading should be taken up to 20 ml rise in volume of KOH solution. After that anaerobic respiration will start.

Experiment # 5

Comparison of Rate of Respiration in Different Plant Parts:

Flower buds, roots and leaves of a suitable herbaceous plant are collected 2 ml of each is measured by displacement of water and placed in the bulbs of three different Ganong’s respirometers. Rate of respiration is measured in each case following Expt. 4.

The volume of CO2 evolved at an interval of 10 minutes is recorded in each case and rates of respiration are graphically plotted for each sample of plant material and compared.

The rate of respiration is always higher in younger actively growing meristematic tissues than that of older and mature parts. There is a direct relationship between the amount of protoplasm and the rate of respiration the greater the protoplaim, the higher is the respiration rate.

The hydration of protoplasm and quantity of respiratory enzymes are al­ways greater in young cells compared to mature and vacuolated cells. Hence the respiratory rate is always higher in young cells which are rich in protoplasm.

Vigorous respiration of root takes place if the space surrounding the roots and root hairs has ample supply of oxygen. In this experi­ment the maximum rate of respiration is expected in case of flower buds than in roots and leaves.

N.B. This experiment may also be performed with different types of seeds (starchy, proteinaceous and fatty).

Experiment # 6

Quantitative Estimation Of CO2 Evolved During Respiration:

(a) By Barcroft-Warburg’s constant volume micro-respirometer:

i. Principle and Description:

A convenient method of measuring the respiration of tissues in minute quantities has been developed by Warburg (1926).

The tissue whose respiration is to be measured is placed in a closed container with an attached manometer which records changes in gas pressure as a result of oxygen consumption or carbon dioxide production.

The apparatus is shown in Figure 23. Each respirometer consists of two main parts, a glass flask f and a manometer m, separable at a ground glass joint j. The tissue is placed in the flask f. When only oxygen consumption is to be measured, Ba (OH)2 or NaOH solution is added to the well w at the centre of the flask.

But when both oxygen consumed and carbon dioxide produced are to be measured, an HCL solution is placed in the side arm a with stoppered neck n in addition to the alkali in w.

The manometer fluid is contained in a rubber bulb b and can be added to or withdrawn from the manometer by adjusting the screws. This enables one to return the right side of the manome­ter to the starting point during making a reading and also to read the pressure on the left arm of the apparatus at constant volume.

A mirror behind the manometer reduces parallax in reading. The manometer is provided with a two-way tap t at the closed end. The reaction chamber is kept in a bath of constant temperature. The entire appa­ratus is shaken to facilitate gas exchange and temperature equilibrium.

It is necessary to know the volume of the apparatus including the manometer to the manometer fluid in order to calculate gas volumes from changes in pressure. The manometer is detached and filled with clean mercury from the 15 cm mark to a marked point about 2 cm above the flask connection.

Now mercury is poured into a beaker and the dry reaction chamber f is filled with clean mercury until it just rises to the marked point on the manometer when the manometer and flask are connected.

This mercury is collected in a beaker and the temperature and weight of the metal are determined. The weight of the mercury in milligrams divided by its density at the observed temperature gives the volume of the apparatus in cubic millimeters.

Brodie solution (23gm NaCL, 5gm sodium cholate, 500 ml water, 5 drops conc. thymol in alcohol, as a preservative, and a few crystals of neutral red to colour) is used in the manometer to increase the sensitivity of readings, and to avoid sticking and other difficulties. This solution has a density of 1.0336 and gives a manometric pressure of one atmosphere (760 mm Hg) at 10,000 mm.

If in addition to these two values, the volume of the apparatus and the normal barometric height of the manometer fluid, we know the temperature, the volume of the material whose respiration is being measured, the volume of fluids (water, NaOH, etc.) added to the reaction chamber, and the solubility of the gas being measured in these contained liquids, the change in volume of the contained gases in cubic millimeters under standard conditions can be calculated with the equation

where X is the volume of gas absorbed (- X) or evolved (+ X) in cubic millimeters (cu. mm) under standard temperature and pressure h is the manometer reading in millimeters (reading of left arm minus right) Vg is the free volume of gas in flask and manometer to manometer fluid (total volume of apparatus less volume of sample, liquids, etc., added to reaction chamber) T is the absolute temperature of the water around the reaction flask if is the volume of all fluids in which the measured gas might dis­solve (ordinarily not including volume of solid samples) a is the Bunsen coefficient of the solubility of the gas being measured in the contained fluids at the temperature T (see below) it is to be noted that Vf x a gives the volume of dissolved gas and that this is added to the free gas (Vg) to give the total volume Po is the normal pressure in terms of the manometer fluid (for Brodie solution 10,000 mm).

In its simplest terms the equation states that the change in gas volume during the experiment is equal to the fractional change in pressure h/Po times the total volume of the gas Vg, with corrections for temperature and the solubility of the gas in the fluids present.

The above equation assumes that the barometric pressure, the temperature, and the vapour pressure of the contained liquids remain constant during the experiment and therefore cancel out.

In practice, the great sensitivity of the manometer makes it necessary to set up an apparatus with the liquids, but without a sample, and to correct the experimental readings by the changes in the manometer of this blank apparatus, which are due to temperature or to barometric variations during the course of the experiment.

This method is most suitable for measuring respiration of minute quantity of respiring material. The reservoir b of the manometer is filled with Brodie solution. 1 ml of the respiring material is placed in the outer part of the flask f 0.2 to 0.4 ml of CO2 free 2N KOH solution is taken in the central cup w and 0.3 to 0.6 ml 2.5 N HCL in the side arm a.

The manometer connections are greased lightly but uniformly. The flask is secured in place with springs or rubber bands keeping the stopcock t open. The temperature of the water bath is kept constant at 30°C.

If only O2 consumption is to be measured, the HGL is omitted from the side arm and one or more samples are set up as desired in different flasks. If both O2 and CO2 are to be measured to obtain RQ, the HCL is included in the side arm and all experiments are set up in duplicate. In either case a flask is set up with a sample but with KOH and other fluid to serve as thermo-barometer.

The stopcock t is left open. The assembled manometers and flasks are set in the water bath and shaken for 15 minutes to attain temperature equilibrium. Now with screw is the right arm of the manometers is ad­justed to 250 point for which they are calibrated (150 to 250 mm), the stopcocks are closed and the time is recorded as the beginning of the experi­ment.

When CO2 production is to be measured, the duplicate flask for each sample is quickly removed, a finger is held tightly over the open end of the manometer to prevent the manometer fluid being blown out or sucked into the flask, the flask is tipped to mix the KOH and HCL solutions thoroughly from the cup w and arm a.

These flasks are returned to the bath the manometer is carefully released, shaken for 5 to 8 minutes and manometer reading is recorded. This is corrected by changes in the thermo-barometer, as CO2 present or produced before experimental time.

The remaining flasks are shaken for 100 to 130 oscillations per minute for one hour or more. Intermediate readings for O2 consumption may be made as desired by stopping the shaker and adjusting the right arms of the manometers to the original point and recording the manometer readings including that of the thermo-barometer.

At the end of the experiment, the total O2 consumption is recorded and absorbed CO2 is liberated by the method used for the control samples taking care to protect the manometer fluid against changes in pressure and to bring the gases at water bath temperature with vigorous shaking before reading the CO2 pressure.

The change in pressure upon the mixing of KOH and HCL gives the ‘h’ reading for CO2. The right side of the mano­meter arm is always returned to its original setting before taking a reading since all of the calculations are based upon a constant volume of gas within the apparatus. The thermo-barometer pressure is always recorded along with each reading.

The proper terms are substituted in the equation

The gas absorbed or evolved is calculated in cu. mm, or in ml per gram of dry tissue per hour. The value Vg varies with the flask and with the volume of added samples or other fluids.

The volume of bacterial cultures and of KOH and HCL solution is obtained by pipetting the volume of seeds, tissues, etc., by displacement. Vf is usually the volume of sample and other fluids for bacterial cultures but does not include the volume of seed tissue.

In experiments in which a constant volume of sample is run at constant temperature, the value of the quantity within the brackets remains constant and can be assigned a value K (flask constant) so that the equation becomes X = AK, in which K is calculated for each flask at each temperature.

The result may be expressed in mg by multiplying the volume of CO2 in ml by the density of CO2 at i particular temperature and pressure.

The effects of temperature or other factors upon the respiration and RQ of seeds and plant tissues may be measured by this apparatus.

(b) By Pettenkoffer’s gas stream method of CO2 estimation Principle and description of apparatus:

The principle of this method is that CO2 liberated by respiratory tissue is removed from its chamber along with CO2 free gas stream and absorbed in baryta (Barium hydroxide solution) taken in Pettenkoffer’s tube to form barium carbonate.

This is then titrated by a standard acid (HCL) to know its CO2 content. CO2 free air is drawn through a system as shown in Figure 24.

At the extreme left there is a soda lime tower containing soda lime for absorbing CO2 of the air entering through its opening at the mouth. The end of the tower is fitted with a tube through which CO2 free air passes into a U-tube containing KOH solution (30%).

The U-tube in turn is connected with another tower containing lime water or B(OH)2 solution which is connected to the respiration chamber by means of a tube. The respiration chamber is again connected to one end of the horizontally placed Pettenkoffer’s tube containing 50 ml of standard N/10 B(OH)2 solution (8-567gm/litre).

The other end of this tube is connected to an aspirator or suction pump. Thus on applying suction at the extreme right, air current enters the system of towers and tubes through the inlet at the top of the soda lime tower.

A mercury trough may be introduced in between Pettenkoffer’s tubes and the aspirator to regulate air flow. All connections should be made air-tight.

At the beginning of experiment, weighed amount of plant tissue is taken in the respiration chamber. All the towers and Petten­koffer’s tubes are connected as described and made air-tight. The inlets of KOH tube and baryta tower must be dipped into the solution but the exit tubes should remain well above the surface of the solution.

Now the aspirator or suction pump is started. Air is sucked out through the end of the Pettenkoffer’s tube at the aspirator end causing the air to bubble into the solution of baryta contained in the Pettenkoffer’s tube through the respiration chamber and other towers successively.

Thus air first comes through the soda lime tower and then through KOH tube and baryta tower, thus becoming completely free of CO2. This CO2 free air containing O2 comes in contact with the plant tissue in the respiration chamber and aerobic respiration takes place as a result of which CO2 is evolved.

This CO2 produced by plant tissue during aerobic respiration then passes through the standard baryta solution of Pettenkoffer’s tube and is completely absorbed by it forming BaCO3.

After allowing respiration to occur for a particular time Pettenkoffer’s tube is taken out and the excess baryta is titrated against Standard N/10 HCl using phenolphthalein as an indicator to estimate the quantity of CO2 from the following relations.

The baryta and the BaCO3 solution of the Pettenkoffer’s tube is quantitatively transferred in a flask, a drop or two of phenolph­thalein solution is added and titrated against N/10 HCL until the pink colour is just discharged.

This gives the volume of residual Ba (HO)2 (not utilised by the CO2 formed). This titration value is subtracted from the titration value of fresh 50 ml sample of Ba (OH)2 solution and weight of CO2 liberated in respiration is calculated from the following equation:

Where Vis the difference between blank and experimental titration values in millilitres, N is the normality of acid used in titration and 22 is the equi­valent weight of CO2 in BaCO3. Since molecular weight of CO2 is 44 and it is absorbed by Ba (OH)2 as H2CO3 the equivalent weight is to be calculated by dividing the molecular weight by 2.

This method sometimes called the “gas-stream method”, has the advantage of accuracy and convenience and of permitting a study of the cell material for an indefinite period under constant conditions.

Here the CO2 yield is obtained in milligrams the result may be divided by thou­sand to give grams or divided by 1-977 (density of CO2) to change to ml of CO2 at 0°C and 760 mm. Hg. It is to be noted that CO2 is calculated directly rather than as the carbonic acid which is actually measured.

Experiment # 7

Determination of Respiratory Quotients (RQ) by Ganong’s Respirometer:

From this experiment, volume of CO2 evolved and O2 consumed during aerobic respiration can be directly obtained and RQ,, i.e., (volume of CO2/volume of O2) can be calculated.

The experiment can be conveniently performed by Ganong’s respirometer described in Expt. 4. The manometer tube and reservoir are filled with brine solution (saturated NaCl solution) and by adjusting the reservoir, the surface of the brine solution is brought to 100 ml mark of manometer.

The weighed equal quantities (2 ml) of tissues whose RQ, is to be determined are taken in the bulbs of two similar types of Ganong’s respirometer. In the bulb of one respirometer 1 ml of 40% KOH solution contained in a small vial is kept along with the tissue.

Total volume of tissue plus KOH solution plus vial should be noted (let it be k ml). The other respirometer contains only tissue in the bulb and its volume is noted (let it be t ml). Now the air within the bulb is brought to atmospheric pressure by turning the stopper.

The level of brine solution is brought to 100 ml mark at the bottom of manometer. This is done in both the respirometers and the connection with the outside air is cut off by turning the stoppers. Now the bulb and the manometer tube up to the level of brine solution contain a definite volume of air having 20% 02 and 0.03% of CO2 on an average.

The setup is placed in dark or covered with black paper for a certain period of time (say two hours) and any change in the reading of brine level is noted. The volume of air in case of the respirometer containing plant tissue only is 100—t and this multiplied by 20/100 gives the volume of O2 in this air.

Similarly the volume of air in case of the respirometer containing KOH vial and the plant tissue is 100 —k and this multiplied by 20/100 gives the O2 in this closed atmosphere.

During the time for which the setup is kept, respiration occurs in the tissues of both the respirometers by absorbing O2 and giving out CO2. In the respirometer containing KOH via), CO2 given out is absorbed by KOH solution but this does not happen in the respirometer without KOH3. Therefore, the brine level rises in the respirometer with KOH and either rises or falls or remains stationary in the respirometer without KOH.

In the respirometer containing KOH, CO2 is absorbed reducing the pressure in the manometer tube and brine level rises because O2 has been used up by the tissue. The more O2 is used up, the more raises the brine level.

Now by adjusting the reservoir the brine level is brought to the same level in both the arms, thus bringing the volume of air in the manometer tube in atmospheric pressure. At this stage the brine level in manometer tube is noted and the difference between the final arid initial readings gives the volume of O2 used by the tissue (let it be x ml).

Now in a respirometer without KOH, O2 is also used up giving out CO2. But in this case CO2 is not absorbed since KOH is not present. If CO2given out is less than O2 used (when fat is a substrate) the brine level will rise in the manometer tube.

If CO2 given out is more than O2 used (when acid is a substrate) the brine level will fall down in the manometer tube and when CO2 given out is equal to O2 used up (when carbohydrate is a substrate), the level of brine remains stationary. Before taking readings the brine level is adjusted at the same level in both the arms.

The difference between the final and initial readings gives the net gas exchange which has taken place (let it be y ml). If the rise of brine level upward is considered as negative change and fall of brine level downward is considered as positive change, the volume of CO2 evolved will be (x – y) ml when brine level rises up and (x + y) ml when brine level falls down. It may also remain stationary when RQ, is unity.

Unity when the brine level in the respirometer without KOH remains stationary indicating that the respiring substrate is carbohydrate.

In this way the RQ for any given tissue may be calculated. It is to be parti­cularly noted that the volume of the closed air within the bulb and the manometer should be equal in both the cases. The respirometers should be of the same size and volume and equal volumes of tissue should be taken in each case.

Since KOH vial is kept in one bulb only, a similar vial containing equal quantity of brine solution may be kept in the other bulb so that same volume of air is present in both the bulbs. Temperature greatly affects the volume of gases and hence both respirometers should be placed at the same temperature.

Experiment # 8

Demonstration of Liberation of Heat Energy During Respiration:

Three thermos-flasks are taken. One contains water-soaked seeds, second dry seeds and the third boiled seeds (dead) and all the lots are of equal weight. The mouths of the thermos-flasks are corked through which passes a thermometer in each flask so that the bulb of the thermometer remains within the seeds. The flasks are left for 24 hours.

Rise of temperature is observed in all the cases.

The rise in temperature of the flasks containing soaked seeds indicates that heat is produced during respiration of seeds. Tempe­rature remains nearly unchanged in dry seeds and completely unchanged in case of boiled seeds. This is because the respiration of dry seeds is almost negligible and in case of boiled seeds nil.

N.B. The mathematical evaluation of heat loss during respiration of one gram mole of glucose is as follows. Every mole of ATP formed from ADP and phosphate requires about 12 K. Cal. of energy. But complete combustion or chemical oxidation of one mole of glucose yields 684 K. Cal. of energy as heat. Therefore, 684—456 = 228 K. Cal. is lost as heat energy. Thus in aerobic respiration of each mole of glucose about = 67 % energy of each glucose mole is carried into 38 mole of ATP. This is called as the “efficiency of energy conservation” in aerobic respiration.

Experiment # 9

Demonstration of Loss of Weight in Respiration:

About 50 seeds are surface sterilised with, 1% HgCL2, washed thoroughly and 5 such seeds are separately placed in ten petridishes containing soaked filter paper. The pertidishes are kept in dark and seeds are allowed to germinate. The fresh and dry weights of each lot of seedlings are taken every alternate day.

The percentage loss in dry weight is calculated in each case and the results are graphically plotted taking loss in weight as ordinate and days as abscissa.

Respiration is a catabolic process which takes place by breaking down of stored carbohydrate and liberating CO2, H2O and energy. Since the seedlings are grown in dark the anabolic process, i.e., photosynthesis, cannot take place and as a result of which loss in weight occurs as the plants grow.

Experiment # 10

Effect of Wounding on Respiration:

Experiment can be conveniently performed either with Warburg’s method or Pettenkoffer’s method. Two lots of potato tubers are taken one lot is slightly larger than the other.

The larger potatoes are peeled off and surface area is made comparable with the other lot. Approximately the equal weights of these two lots are washed and dried and the two samples are placed in two respiration chambers of the Pettenko­ffer’s apparatus or in the flasks of Warburg’s apparatus. The rate of respiration is determined in both the cases at a constant temperature.

Respiration rates in millilitres of CO2 per gram dry tissue per hour are plotted. The dry weights of the samples are determined at the end of the experiment.

Injury to a given plant tissue often causes the respiratory activity to increase. Generally, in case of injured plant tissues the rate of respiration increases for the time being and this increase gradually rises to a maximum point and then the rate decreases.

Wounding generally initiates meristematic activity in the area of the wound, resulting in the develop­ment of “wound callus”. It has been shown that a considerable increase in sugar content (about 70%) around the injured cells takes place.

Perhaps the increase in respiration due to wounding is caused by increased avail­ability of respiratory substrate and meristematic cells.

Experiment # 11

Effect of Pre-treatment with Carbon Dioxide on the Rate of Respiration:

Equal weights of three lots of potato tubers are taken. Two lots are taken in two petridishes placed on, two ground glass plates and each is covered with a 1litre bell jar having an outlet at the top (Figure 25).

The lower rims of the bell jars arc made air-tight with grease. The bell jars are partially evacuated with the help of a suction pump. Now CO2 is passed from a Woulfe’s bottle (CaCO2+HCL) into one bell jar for 10 minutes and to the other for 20 minutes. The outlets are then closed and tubers are kept in these atmospheres for about three hours.

The control lot is also placed under a bell jar for the same period of time under normal atmosphere. A centrally placed thermometer records the temperature. After the stipulated time the tubers are taken out and rates of res­piration are determined with the help of Ganong’s respirometer.

The rate of respiration in each case is graphically plotted and compared.

Increasing concentration of CO2 has a definite repressing effect on respiration. Since the direct measurement of respiration rate in terms of CO2 evolution and simultaneous increase in CO2 concentration is difficult with ordinary apparatus here the effect of pre-treatment of CO2 is studied. CO2 input raises the internal concentration of CO2 considerably and limits respiration by its toxic effect.

Experiment # 12

Effect of Moisture Content on Respiration of Grains:

About 300 grams of dehusked rice or wheat seeds are taken in a beaker and dried in an oven at 40°C for 24 hours. These seeds are divided into 5 lots. The initial moisture content of one lot is deter­mined. Water is added to the other 4 lots and each lot is soaked for 5, 10, 15 and 30 minutes separately.

The moisture content of each lot is then determined by taking a portion of seed from each lot. Equal weights of seeds from each lot including un-soaked one are taken in Ganong’s respirometer and rate of respiration is measured.

The rate of respiration is expressed in terms of millilitre of CO2 evolved per gram of dry seeds per hour and graphically plotted in each case.

Within certain limits, moisture content of tissue affects its respiratory rate. In dormant seeds water content is generally less than 10% and their respiratory rate is very slow.

Seed, when come in contact with moisture imbibe water and swell and their respiratory rate gradually increases. The moisture content of the tissue increases the amount of soluble respiratory substrate and also the activity of the protoplasm by the enzymes.

Experiment # 13

Effect of Food Supply on Respiration:

One lot of leaf sample is collected from rice plants which were previously kept in dark for 24 hours and another lot is collected from rice plants previously kept in light for 24 hours. The rate of respiration of equal weights of each sample is measured in a Pettenkoffer’s tube or in Ganong’s respirometer. The dry weight of each sample is determined.

The results are expressed as millilitre of CO2 evolved per gram of dry tissue per hour.

The rate of respiration of a given tissue is governed by the concentration of the soluble respirable substrates. Since organic materials are oxidised during respiration, the amount and kind of materials present in the cells appreciably affect both the rate and course of respiration.

The rate of respiration increases due to increased carbohydrate production as a result of photosynthesis and decreases due to lower carbohydrate content in the dark. Thus the concentration of respirable substrate may limit the rates of CO2 production or O2 uptake.

N.B. Increased respiration is also observed when various sugars (Especially sucrose, glucose, fructose or maltose) are supplied to floating leaves or other tissues in solutions.

Experiment # 14

Determination of Rates of Respiration and Nature of Substrates by McDougal Respiroscopes:

This is a simple apparatus fixed in a wooden frame (Figure 26) which consists of a pair of vertical tubes. The upper end of the tube is wider than the lower end which is graduated. The lower end of the graduated tube dips into a beaker containing brine solution.

The upper bulb-like wider ends of the respiroscopes are closed by means of corks through which pass two small tubes having bent ends. The upper ends, i.e., the outside ends of the bent tubes are fitted with stopcocks.

From the lower bent ends of the two tubes, two small vials one containing KOH pellets hang within the bulbs. Equal amounts of germinated starchy or fatty seeds (seed coat removed) are placed within the wider bulbs of the respiroscope on a soaked cotton plug. A thermometer may be centrally placed to record temperature.

The stopcock is then turned to make connection with atmospheric air. The brine solution rises through the graduated end of the respiroscope and becomes stationary at the brine level of the beakers. The stopcock is closed and the level of brine solution in both the tubes is recorded. The rise of brine columns in the tubes is recorded at an interval of 15 minutes for 2 hours.

The rate of rise of water column indicates the rate of respiration.

The partial vacuum created due to absorption of O2dur­ing respiration cannot be filled up by CO2 released and this vacuum is then filled up by the brine solution. The volume of CO2evolved during respiration by starchy seeds is equal to the volume of O2consumed (RQ = 1). But in case of fatty seeds the volume of CO2 liberated is less than the volume of O2 used up (RQ, < 1).

Hence the rate of respiration as measured in terms of O2consumption is less in case of fatty seeds than starchy seeds. The depression (when RQ,> 1) or elevation (when RQ, < 1) column of brine solution in the control McDougal res­piroscope (without KOH) indicates the nature of Substrate. If the brine level is stationary (RQ, = 1) then the substrate is carbohydrate.

Experiment # 15

Respiration of Roots of Intact Plants:

The adventitious roots of rice or wheat plants are care­fully washed with water and placed in a bottle containing water which is made slightly alkaline with dilute NaOH solution. This is coloured pink with addition of a few drops of phenolphthalein.

A second bottle b prepared in the same way, stoppered tightly and left without a plant. Both the bottles are allowed to stand in diffused light and the solutions are examined from time to time and change in colour is carefully noted in each case.

The pink colour of the solution in the bottle containing the plant gradually fades and ultimately becomes colourless after a consider­able time. The solution of the other bottle remains as such.

During respiration of roots CO2 is released which is converted to H2CO3when comes in contact with water. This acid neu­tralises the dilute NaOH solution and pink colour of the solution fades.

When a portion of this neutralised solution is gently boiled for few minutes the pink colour reappears because CO2comes off on boiling leaving the solution alkaline again.

Experiment # 16

Demonstration of Continuity of Intercellular Spaces:

A conical flask is taken and half-filled with water. The mouth of the flask is fitted with a cork having two holes, through one of which is inserted a long petioled leaf of arum (Colocasia) so that the cut end of the petiole remains well under water.

Through another hole is inserted a bent glass tube which is connected to a suction pump. The end of this bent tube remains well above the water surface. All connections are made air-tight. The air within the flask is drawn out by the suction pump.

Bubbles are seen to come out from the cut end of the petiole into the water of the flask.

The experiment shows that as the air is sucked, the at­mospheric air enters through the stomata of the leaf and through the inter­cellular spaces ultimately comes out through the cut end of the petioles. This shows that stomata and intercellular spaces form continuity and are involved in gaseous exchange.

Keep freshly picked chilies in a polythene bag in the fridge for up to two weeks.

I freeze chilies in bags in the right number for the recipe I want to use them for. For example, my Thai chili sauce recipe uses 36 chilis so I freeze 36 in one bag and clearly label it.

If you want to save seeds for next season, choose a healthy specimen and remove the seeds before freezing – dry well and store for next year in a paper envelope.

If you haven’t tried growing chili peppers yet, give it a go. Remember, they need good nutrition and warm, humid conditions to grow well. Follow our tips and you’ll get a bumper crop. We’d love to hear about your chili growing success.

Facts About Mother-in-Law&aposs Tongue

Common Names

Snake plant, viper&aposs bowstring hemp, Saint George&aposs sword

Scientific Name

Bright, indirect sunlight (some direct light is ok)

Once a month keep the soil dry

Ideal Temperature

60° to 80ଏ (16° to 27ଌ) Prefers warm to hot temperatures

Doesn&apost require it. For fast growth, fertilize once in the spring and once in the summer.

Mother-in-Law&aposs Tongue plant in large pots

Open Research

All relevant data can be found within the manuscript and its supporting material.

Figure S1. Extractable transglucanase activities from different Equisetum parts.

Figure S2. Effect of BSA on EfHTG activities (XET, MXE, CXE).

Figure S3. Statistical evaluation of stimulatory effect of non-enzymatic Equisetum polymers.

Figure S4. Safranin O uptake by hydroponically grown Equisetum fluviatile shoots.

Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Watch the video: Ρυγχίτης και πυρηνοτρίτης εκτός από τον δάκο προσβάλλει τις ελιές απαραίτητη η καταπολέμηση για τη (January 2022).