USE OF RADIOISOTOPES IN THE FIELD OF AGRICULTURE

DR.S.M.ALAM & M.A.KHAN
July 27 - Aug 02, 2009

Never in the annals of history has a scientific discovery so profoundly affected the course of human destiny as the discovery of atomic energy. Its potential for destruction is enormous and its use for economic development is unlimited.

The co-existence of fear of annihilation and hope for the progress of human welfare through atomic energy application has ushered us into the present era rightly known as the 'Atomic Age'.

The emission of radiation in the form of particles or rays is known as radioactivity. The discovery of artificial radioactivity by Henri Bacquerel in 1896 has greatly enlarged and expanded extensively study of the various problems and the subsequent availability of radioisotopes in large quantity for research work. This made it easy to bring in to light many complicated functions of daily life, which conventional means could hardly solve.

By radioisotopes or radiation, we generally mean some extraordinary type of energy, which is emitted by radioactive isotopes or radioactive materials. Such rays are alpha, beta, and gamma, which are invisible, spontaneous, and penetrating. These rays are generally harmful for all living beings and their presence can be easily detected with the help of the some latest monitoring devices such as Geiger Muller Counters or Scintillation Counters and Gamma Survey Meters.

These instruments are used for the detection of even the minuscule quantity of radioactive elements present anywhere on the earth surface. Thus, the tool (radioactivity) is proving very helpful in several fields including agriculture.

To the world today, these new tools are unlocking the secrets of many agricultural problems, which could never have been possible by conventional means. Scientific research is conducted all over the world putting radioisotopes in use with successful scientific achievements.

Radioisotopes are more widely used in the field of agriculture than in any other field of science and their application is leading us to the solutions of agricultural problems in a shorter time and more precisely.

Radioisotopes and radiations give us the opportunity to clear the events that once were mysterious in the nutrition and growth of plants and evolution of new varieties.

They help us to clear the causal factors, which produce the ill effects to the plants in different ways. Thus, radioisotope has become a very important aid to scientists dealing with solution of agricultural problems. In addition to this, the radioactive tracers and radiation sources have become indispensable to all the intricate agricultural research problems.

Today, some of the radioisotopes such as P32, C14, N15,Ca45, H3, Na22, Na24, Co60, Cu64,Fe55, Fe59, Mn54, K42, Rb86, S35, Zn65etc. are available in sufficient quantity and have been widely used to investigate a number of problems related to agriculture and other fields. These radioisotopes have very short or very high half-lives and their uses are only depending on their lives.

In agriculture, radioisotopes are used in the nutritional studies of trace elements, diet additives, diary chemistry, biochemistry of milk production, mechanism of photosynthesis, plant pathology, plant protection including action of insecticides, metabolism in plants, uptake of fertilizers, ion mobility in soils and plants and food preservation.

Radioisotopes have a significant application in the nutrition of plants. Like other living organisms, plant can also grow strong and healthy if grown under proper nutritional condition. While within sufficient nutrition, their growth slows down.

In order to determine the correct nutrition for a plant we need to know the exact soil plant relationship and the factors involved therein. In recent years, many different conventional methods have been proposed and tried to determine this very complicated relation. But, a few of them have given the satisfactory information on the soil-plant relationships. Although, the investigations with radioisotopes are quite limited, the results obtained by using this new technique are very satisfactory, reliable, and helpful.

Tracer techniques are now being widely used in almost all the fields of plant physiology, soil chemistry, and plant biochemistry. In applying the tracer technique, a minute quantity of radioisotope element is usually mixed with ordinary element of same kind and the whole batch become 'tagged' and may be followed through complicated chemical reactions.

Application of radioisotopes and radiation in agriculture research has the following especial advantages.

1. With the help of radioisotopes, we can easily locate the presence of a single atom and molecule and their movement. Hence, they give research workers the opportunity to follow up systematically all kind of processes that are related to the nutrition of plant from germination to maturity.

2. Very small quantities of labeled nutrients can be accurately measured in presence of large quantities of other nutrients.

3. Autoradiography can locate nutrients.

4. Tracer technique enables one in tracing those elements taken by the plants accurately and precisely.

5. It also helps to study accurately the effect of one element upon the absorption of another and their interaction by plants and now it has become very easy to study properly the phenomenon of interaction among the mineral nutrients.

The production of radioisotopes by nuclear reactors and by other atomic installations has increased the use of radioisotopes in the field of agriculture.

Radioactive phosphorous (P32) are used to determine the fertility of different soils. Using rice as a test crop, studies have been conducted on the absorption, translocation, and distribution of phosphate, carbon, and nitrogen with the help of super phosphate, urea, and ammonium sulphate labeled with P32, C14, and N15, which are applied in soil and on leaves as spray thereby fruitful results have been obtained.

The scientific endeavors are envisaged in developing the high yield, improved lodging resistant, improved seed quality, changing maturity times increased yields, disease and insect resistant varieties of important crops like cotton, rice, wheat, chickpea, mung bean, lentil etc. by using induced mutations through gamma radiations, plant molecular breeding and biotechnology. Now more than 50 different varieties of wheat, rice, cotton, sugarcane, lentil chickpea, mung bean, etc. have been evolved.

The radioisotopes have also been used in the disinfection of stored food grains, mutation breeding, eradication of insect and pests and food preservation in many countries of the world.