Isotopes: Isotopes are the atoms of the same element having the same atomic number but different mass number. The nuclei 1H^1, 1H^2, and 1H^3 are the isotopes of hydrogen. In other words isotopes of an element contains the same number of protons but different number of neutrons. Radio isotopes are of two types. 1.Natural radio isotopes and 2. artificial radio isotopes. For many applications, radio isotopes are produced artificially.
Production of Artificial radio isotopes: Artificial radio isotopes are produced by placing the target element ( whose radio isotope has to be prepared) in a nuclear reactor, which is the very good source of neutrons. For example: 15P^31 + 0n^1 —> 15P^32* + ‘gamma’.
Another method of preparation of radio isotopes is to bombard the target elements with particles from particle accelerator like cyclotron..
For example: 11Na^23 + 1H^2 —-> 11Na^24* + 1H^1.
Application of radio isotopes in agriculture:
Insect Control using radio isotopes:
About 10% of the world’s crops are destroyed by insects. In efforts to control insect plagues, authorities often release sterile laboratory-raised insects into the wild. These insects are made sterile using ionizing radiation – they are irradiated with this radiation before they hatch. Female insects that mate with sterile male insects do not reproduce, and the population of the insect pests can be quickly curbed as a consequence. This technique of releasing sterile insects into the wild, called the sterile insect technique (SIT), is commonly used in protecting agricultural industries in many countries around the world.
The technique of controlling insects using Radioactive isotope is considered to be safer and better than conventional chemical insecticides. Insects can develop resistance against these chemicals, and there are health concerns about crops treated with them.
SIT is in use in several countries, with support from the UN Food and Agriculture Organisation (FAO) and the International Atomic Energy Agency (IAEA). Australia is a large producer of many fruits and sterilizes up to 25 million fruit fly pupae per week.
Food Treatment and Preservation using Radio isotopes:
Ionizing radiation is used as an alternative to chemicals in the treatment and preservation of foods. A French scientist first discovered that radiation could be used to prolong food shelf life in the 1920s and it became more widely used in World War II. Today, astronauts often eat radiation-preserved food while on space missions. This is most important application of Radio isotopes in agriculture and food preservation.
In meats and other foods of animal origin, irradiation destroys the bacteria that causes spoilage as well as diseases and illness such as salmonella poisoning. This allows for a more safer food supply, and meats that can be stored for longer before spoilage. Additionally, irradiation also inhibit tubers that cause fruits and vegetables to ripen. The result is fresh fruits and vegetables that can be stored for longer before ripening.
The irradiation technique is particularly important when exporting to countries with tropical climates, where foods can be spoiled easily due to the warm temperatures.
Irradiation of food is carried out using accelerated electrons (beta radiation), and ionizing radiation from sources such as the radioisotopes cobalt-60 and cesium-137. X-rays are also sometimes used. None of these sources of radiation used have enough energy to make the exposed foods radioactive.
Role of radio isotopes in Increasing Crop Yield:
Radio isotopes in agriculture help to increase the crop yields. Radio phosphorous (15P^32) incorporated with phosphate fertilizer is added to the soil. The plant and soil are tested time to time. Phosphorous is taken by the plant for its growth and radio phosphorous is found to increase the yield.