Week 12 - Increasing Yields, Selective Breeding, Controlling Pests and Environmental Management

Our population is steadily growing. Decreases in infant mortality and increases in life expectancy means that more people are living to become adults and those adults are living longer lives. Higher standards of health care across the world have made this a worldwide trend, not just in the developed nations. In short - the human population is EXPLODING!

To cope with this, farmers have had to develop new strategies for getting more food. All these people in our world need plants for food and fibre. It would be easy to say, "Just grow more crops." This is not really the case. We are limited by the amount of arable farm land available. Some of our land is not suitable for farming. It is too cold, forested, dry, or wet. 

However, we can change this. We have technology that can increase the yield of plants by modifying the environment.

If an area is too dry, we can irrigate the area. This provides water for plants to grow. Water can be pumped from a body of water or from underground. It then travels through pipes until it reaches the farmer's land. The farmer can build an irrigation system to deliver the water to the plants that need it.

If the area is too cold, we can use greenhouses. These greenhouses can be built to have a controlled temperature and light in all seasons, so we can have fresh vegetables even in the winter. Greenhouses also offer a way for us to have a high yield for the small area that they take up. A greenhouse can produce more food than an open field because the environment is controlled for the best growing conditions for the plants.

If the soil in an area is not suitable for growing, we can use a greenhouse with artificial soil. Hydroponic systems allow plants to grow in gravel or coarse sand. Water enriched with the right balance of nutrients is circulated around the roots of all the plants. Plants are monitored to ensure they are growing correctly. Most commercial greenhouses use hydroponic systems for growing their plants.

Selective breeding is as important for increasing yield as is modifying growing conditions. If human needs are to be sustained, selective breeding and genetically modified plants are necessary.

In western Canada in the 1800s, farmers had difficulty producing wheat, because the varieties that were available grew best in European conditions. Since the growing season in Canada is significantly shorter, these crops were frequently destroyed by frost before any grain had been produced. This problem was solved by Canadian Charles Saunders, by developing a variety suited to Canadian climates. Saunders' variety is called Marquis, which grows and ripens in as little as 100 days, reducing the crop loss due to frost. This variety was first available in 1909, and by 1920, 90% of wheat grown in western Canada was Marquis wheat.

Plants are selectively bred for a variety of reasons, depending on the characteristics which are desired. For example, if the plant is to be used for food, it could be bred for taste and appearance. If it's a rose or an ornamental flower, it could be bred for beauty and fragrance. Selective breeding means that people chose specific plants with particular characteristics, and encourage these plants to reproduce.

One of the most controversial topics currently in the news is that of genetically modified foods. Genetic modification is a type of biotechnology that focuses on particular genes in plants (genes are what give living organisms particular characteristics, located in cells). This technique allows plant producers to achieve the same goals as traditional selective breeders in much less time with greater selectivity. Some examples of genetically modified plants include fruits and grains that have been made resistant to viruses or pests. Genetic modification is controversial because of the potential effects on the food chain by altering characteristics within species.

QUESTION

Which characteristics are bred for in apples?

HYPOTHESIS

Form a hypothesis about which apple will perform the best. Remember to explain the reasons for your statement as well.

MATERIALS

Small Knife

Oven

Baking Pan

Aluminum Foil

Oven Mitts

Several varieties of apples (2 of each variety)

Small paper lunch bags (1 per apple variety)

PROCEDURE

1. Observe the general appearance of the apples. What is the colour of the exterior and the inner pulp. Are there any blemishes in or on the apple?

2. Cut one apple of each variety into 6-8 slices. Leave the other apple whole.

3. Taste one or two slices of each apple and rate their flavour and juiciness on a scale from 1 to 5 (5 is the best).

4. Wrap the remaining apple slices in some aluminum foil. Do not add butter, sugar, or spices. Put the packets on a baking tray and bake the apples at 350 degrees F for 30 minutes.

 
5. Remove from the oven with oven mitts and let them cool for 2 minutes.

6. Record their texture, appearance, and taste after being removed from the oven.

7. Take the remaining whole apples and place each one in its own paper bag. Label each bag with the apple type and leave them on the counter or in a cupboard for one week. Observe the characteristics of the apple after a week has gone by.

As the human population continues to grow, we continue to use technology and science to help us produce more food. We create large continuous fields of the same kinds of food called Monocultures. Wheat, canola, oats and barley grow for endless kilometres on the open prairie. What are the positive and negative effects of this type of farming?

In order to protect crops and increase yield, farmers and foresters will use any number of methods. Each of these methods will have consequences that can be both detrimental and advantageous to the grower. Sometimes, we do something to fix a problem and find that we have accidentally created a whole new problem. In coming up with solutions, we must look at the whole picture.

In 1939, the chemical DDT was discovered to be a powerful insecticide. From that time until 1960, it was extensively used to prevent disease and increase crop yield, by killing insects. However, in the 1950s, scientists began to notice that some birds of prey were decreasing in numbers. Upon closer examination, they found that DDT builds up in the fatty tissue of the birds that eat these insects. Through experimentation, scientists found out that DDT interfered with the ability of mother birds to provide enough calcium to harden the shells of their eggs. Therefore, the bird numbers were decreasing because their young would not survive. In some places around the world today, DDT is still being used. What effect would this have on Canada? What effect does this have on the global food chain?

Herbicides are chemicals that kill targeted plants considered to be pests by man. Man considers weeds to be competitors for their main crop. They take valuable nutrients and water from the soil, and they compete for sunlight with the desired crop, thus reducing yield. For instance, the common dandelion stores nutrients in its roots through the summer so that in early spring it can get a strong start before the competitors. Its broad leaves allow dandelions to shade out many of the plants they grow with. They are able to create seeds all summer long, each flower creating hundreds of seeds which are carried a long distance by the wind. They are adapted to all kinds of soil, including those with poor nutrients. They are even well adapted to lawns that are frequently mowed. To top this all off, dandelions also release a chemical agent to slow down the growth of grass and other plants nearby. Herbicide and fertilizer combinations such as "Weed and Feed" are used by consumers to not only make the grass on a lawn healthier, but also to kill the weeds.

An insecticides is also a chemical control, but meant to kill insects instead of plants. Unfortunately, insecticides can also kill helpful insects, such as those that pollinate crops. Some insects are food for other animals. By using insecticides, these animals will have less food, or will be harmed by eating poisoned insects, or drinking water that has been contaminated by insecticides.

One of the issues with using chemical control pesticides is the ability for insects and weeds to become resistant to the chemicals. In other words, as insects reproduce very quickly, they can often rapidly adapt to the new challenges in their environment. So let's take a field, and say that we spray it and 99% of the insects die, but 1% do not. This 1% will reproduce, and the next time a chemical is sprayed, their offspring will have a higher chance of surviving. Scientists have discovered that as pesticide use increases, the number of insect species resistant to pesticides increases as well. Food producers should be aware of this, and only use pesticides when absolutely necessary. The only way to deal with resistant insects is to use higher doses of the chemical, or develop new pesticides. One of the major human concerns with pesticides is whether or not they are still in our food when we buy them at the grocery store. Some have thought that pesticides may be linked to cancer. We have a delicate sustainability issue. Do we attempt to produce food with chemical controls that have high yields and can feed the world's population, but risk the side effects of ingesting pesticides. Just as in the example of the birds of prey and DDT, how much bioaccumulation of chemicals can the human body sustain without there being any harmful effects?

Just as we worry about pesticides bioaccumulating in our bodies, we have to worry about what happens to pesticides as some of them wash off plants and leave residue in the soil and water. If the pesticide doesn't easily decompose, it can build up, making the soil potentially toxic and the water undrinkable.

Farmers who chose to run organic food productions must pass strict inspections in order to be certified as organic. Producing without chemicals can be very expensive and requires much extra monitoring and lots of extra work. Nonetheless, organic growers can demand higher prices for their produce, and their land has less chance of residue buildup. Consumers who buy organic foods will pay a little bit more for their food, but have less worry about bioaccumulation of chemicals.

Sometimes, the unintended consequences of household actions (such as turning a light on) may not seem that significant. However, on a larger scale, these effects can become a serious environmental issue. As every action and decision has intended and unintended consequences, it is important to balance the needs of humans with the needs of the environment. Keeping this balance is called environmental management. In order to properly manage the environment, we must consider all the factors that play a part in decision making. Human beings are motivated to change their environment for numerous reasons, including economical, ecological, political, recreational, or health-related.

When a farmer purchases his land and plans his farming operation, he must look at a number of factors before deciding which crops, and how many, to put in. If a farmer decides to plant 20 different items, it may take more time and money to manage these crops and get them to market. However, if a farmer chooses monoculture, or the planting of just one crop, he will spend less money because he can specialize on that crop. Only one type of fertilizer or chemical control will need to be used, and the equipment can be customized to making the harvest of the crop much easier. Farms that are intended to produce goods for more than just themselves will tend to specialize. However, farms in rural developing countries may plant numerous crops in order to meet the nutritional needs of the individual family.

• Agricultural land
• Water
• Labour
• Money
• Man-made Inputs
• Technology