Selection of agricultural crops
Selection is an important direction of agronomy. For a long time plant-breeders have been breeding new varieties of drought-resistant grain crops and other agricultural plants which are resistant to the unfavorable climatic and weather conditions. At the same time they are characterized by high yield productivity. The agricultural biotechnology is of the greatest importance. It should create the new highly productive varieties and hybrids of the agricultural plants, biological means of the plant protection, different preparations and the ways of the waste recovery.
Thanks to the cell engineering the researchers have bred an unvirus substance for different potatoes varieties. They have been breeding new varieties and hybrids of grain crops, fruits and vegetables. They breed seeds of sugar beets in the form of seedlings. Later they are ready for the further sowing in the granule form.
The biotechnology is based on the fact that a celled organism is fully preserved by a gene of the previous type. Simultaneously this simplest organism has much common with the microorganism. Exactly it is a basis of the cell engineering and biotechnology. The plant cells are able to divide without any limit.
It’s necessary to keep the cell sterility and that’s why we use special utensils. The cell amount for the cultivation is provided with the help of the plant organs processing. Their cultivation is provided into separate cells. They are put on the nutrient environment.
The gene engineering is based on the molecular biology. It gives the possibility of inserting changes into the molecular interaction of the principal molecules inside the cell and outside it.
Recombinant DNA is used and will be used in the work with microorganism for the production of different valuable substances in medicine, biochemical industry and agriculture. Besides their use is connected with two important discoveries. New techniques developed a rapid analysis of complicated biological molecules. After analysis came synthesis. The first gene was synthesized. Then it became possible to synthesize necessary genes.
The construction technology of recombinant DNA is the most important achievement of the biotechnology. The agricultural, possibilities of such techniques are almost as exciting. For example, it may become possible to transfer the nitrogen-fixing genes of certain bacteria to plants such as cereals which are unable to fix nitrogen. Should this prove possible, the savings in terms of fertilizer and improved soil fertility will be enormous? Similarly of there is the prospect of transferring to a number of different crops civic genes responsible for improved yield or pest resistance
2. Answer the following questions:
1. What is the selection purpose?
2. How are new plant varieties characterized?
3. What should the agricultural biotechnology create?
4. What have the plant-breeders been breeding?
5. What is the biotechnology based on?
6. What is the basis of the cell engineering?
7. What do we use to keep the cell sterility?
8. What is the gene engineering based on?
9. When is the recombinant DNA used?
10. What are two important discoveries in the gene engineering?
11. What substances are transferred for cereals?
Самостійна робота №9
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Types of tractors
Four-wheel tractors are produced with engines of any size from the small tractor of about 15 horse power (hp) to the giants with the engine power more than 200 hp. There are two basic types of four-wheel-drive tractors. One type has four large equally-sized wheels; the other has small front wheels and large rear wheels.
Most equal-sized wheel models have engines with at least 75 kw (100 hp) and tractors of this type with 150 kw engines are in use in some areas.
Ploughing and heavy cultivations are ideal work for these big tractors.
Many of the four-wheel-drive tractors with small front wheels are basically general-purpose tractors and are able to transmit the engine power to the front wheels. The four-wheel-drive tractors can move along roads and their pulling power is greater than the pulling power of the two-wheel-drive tractors.
Row crop tractor has narrow tyres which can be placed closer or farther apart according to the distance between the rows that must be cultivated. It has a light-weight design and good visibility. It uses a diesel engine from 30 to 4-5 hp.
The general-purpose tractor does most of the work on the farms. It has powerful hydraulics and is able to pull heavy loads at the drawbar. This type of tractor is heavier than the row crop tractor and its weight is used to increase wheel grip.
Track laying tractors or crawlers are used for dam building, road making, drainage work. This type of tractors has low operating speed but it does less damage to the soil than the large powerful wheeled tractor.
2 Заповніть пропуски:
The tractor can supply power to the machines from the ... (power-take-off shaft, belt pulley, three-point linkage). 2. The tyres can be placed closer or farther apart ... (according to, by means of), distance between the rows. 3. The crawlers are usually ... (small, large, various). 4. The tractor can ... (increase, pull, do) machines. 5. The crawlers are able to (produce, push, drive) heavy loads. 6. Implements are mounted on the tractor by means of ... (a belt pulley, tyres, a three-point linkage). 7. The fuel should be . . . (heavy, clean), and have no water.
Самостійна робота №10