eChapters

9.1 Potential Tracer Difficulties and their Corrections

In radioactive measurements, the observed counting rate is not equal to the true disintegrations rate of the sample since a number of factors like nature of detectors tend to increase it or, in a majority of cases, decrease the actual counts. Some of the important factors responsible for this are

1.Background,

2.Backscattering

3.Absorption

4.Self absorption

6.Geometry

7.Instrument efficiency

Although some forms of electromagnetic energy, such as light and heat, can be detected by the human senses. One of the greatest draw backs to high energy radiation is the inability to detect it. We cannot see, feel, taste, smell, or hear the various forms of ionizing radiation. Fortunately, ionizing radiation interacts with matter which makes detection and measurement possible by utilizing specialized equipment. In this section we want to introduce you to the various ways and means of detecting and measuring ionizing radiation.

As mentioned previously, Becquerel discovered radioactivity because it left marks on photographic film as a means of detecting radiation. However, there are more definitive means commonly used by scientists and technicians who study and work with radiation. The equipment utilized for the detection and measurement of radiation commonly employs some type of a substance or material that responds to radiation. Many common methods use either an ionization process or molecular excitation process as a basis. Remember that we stated earlier that radiation interacts with matter. For detection and measurement purposes the process of ionization is the most commonly employed technique, based on the principle of charged particles producing ion pairs by direct interaction. These charged particles may collide with electrons, which remove them from their parent atoms, or transfer energy to an electron by interaction of electric fields.

7.1 Measurement of Radiation Dose

Radiation dosimetry involves the measurement of the energy actually absorbed in a substrate exposed to ionizing radiation. The radiation may be either electromagnetic or corpuscular in nature. The passage of electromagnetic radiation through a substrate causes ionization by virtue of the secondary electrons released. Particle radiations on the other hand, ionize directly because they are charged, or indirectly through the charged particle resulting from a collision with a substrate. Alpha, beta particles, and protons yield primary ionization. Gamma rays and neutrons produce ionizing radiation by their interaction with the substrate in passage through it.

Although a number of radioactive isotopes are found in nature, most of the isotopes used as radioactive tracers are produced artificially. Methods for producing radioactive isotopes include nuclear fission and the bombardment of selected materials by neutrons or positively charged particles.

6.1 Production of Radioactive Nuclides

Nuclear Reactors

In a nuclear reactor, a fissionable nuclear fuel such as ²³⁵U or ²³⁹Pu is placed in a defined geometry within the reactor core. Fast moving neutrons released as the ²³⁵U or ²³⁹Pu nuclei fission are slowed to thermal energy (0.025 eV) by a low-Z moderator such as water, heavy water, beryllium, or graphite surrounding or mixed intimately with the nuclear fuel. The slowly moving neutrons are absorbed by addition of ²³⁵U or ²³⁹Pu nuclei, and a chain reaction is maintained. The rate of absorption of slow neutrons by fissionable nuclei determines the fission rate for the reactor and is controlled by placing inert neutron absorbers in the reactor core. Typical neutron absorbers, usually termed control roads include boron and calcium. Heat generated in the reactor is removed by a coolant such as water or one of a variety of gases or liquid materials.

Carbon dating uses the half-life of Carbon-14 to find the approximate age of an object that is 40,000 years old or younger.

5.1 What is radiocarbon dating ?

Radiocarbon dating is a method of estimating the age of organic material. It was developed right after World War II by Willard F. Libby and coworkers, and it has provided a way to determine the ages of different materials in archeology, geology, geophysics, and other branches of science. Some examples of the types of material that radiocarbon can determine the ages are wood, charcoal, marine and freshwater shell, bone and antler, and peat and organic-bearing sediments. Age determinations can also be obtained from carbonate deposits such as calcite, dissolved carbon dioxide, and carbonates in ocean, lake, and groundwater sources.

4.1 Selection of Isotopes for Tracer Studies

In radioisotopes we have all the essentials of a powerful research tool, a non-destructive means by which atoms could be followed and detected in the organism. Application mainly depends on the fact that chemical properties of the isotope of an element are essentially identical.

The basic requirement of a tracer is that it be

1.Chemically and physically, virtually equivalent to the substance it represents or displaces and that it, in no appreciable way, affect the system differing from its normal counterpart.

2.Radioactivity could be detected directly and

3.Unaffected by the physical or chemical treatments that are given. Hence, this has been used widely in the investigations of the various problems in biology, chemistry, physics and other fields like agriculture.

Radioactivity

The discovery of radioactivity, in general, actually came about on a few different fonts. First was the discovery of x-ray radiation that was artificially generated in a laboratory, followed by the discovery of several elements that naturally emit radiation when the nucleus of the atoms disintegrates or decay. These are the elements that today are called radioactive elements and are said to have unstable nuclei.

2.1 Isotopes

In 1913, J.J. Thomson and Aston introduced atmospheric neon into the positive ray apparatus and got two parabolas corresponding to masses 20 and 22, with the intensities of the tracks corresponding to the ratio of 9:1, irrespective of the condition of discharge and pressure. This indicated that neon existed in two forms having atomic weights 20 and 22, and at the same time it could not be distinguished chemically. These two types are known as isotopes of neon (iso = same, topas = place in the periodic table). When the average atomic weight of the ordinary neon was calculated based on the abundance of these two forms in the ordinary neon, it was found to be 20.2 which agreed the chemical methods. Thus the existence of isotopes of a given element was discovered.

Formerly isotopes were defined chemical properties but with different atomic weights, the same atomic number and occupying the same position in the periodic classification. Later this definition was slightly modified and now isotopes are defined as nuclides with the same number of protons but differing in the number of neutrons, for example, ordinary hydrogen (also called protium ; proton =1 and neutron =0), deuterium (heavy hydrogen ; proton =1 and neutron = 1), and tritum super heavy hydrogen (proton =1 and neutron =2). Investigations using mass spectrographs have revealed more than 280 isotopes which are stable artificially radioactive isotopes.

Even though we are now in the atomic age, the idea of the atom is not new. More than 2,000 years ago, the Greek philosopher Democritus suggested that any matter is composed of tiny indestructible particles called Atoms. The word atom is derived from the Greek word Atoms meaning something that can not be cut further. However not much attention was paid to this concept till 1808, when Dalton proposed the famous “Atomic theory”. According to this theory, “all matter is composed of tiny indivisible particles called ‘Atom’. Combining the ideas of Lavoisier, Boyle and his own, Dalton proposed that atoms of elements combine together to make molecules of a compound. This was a great step in the concept of the atom and compounds, since this gave a clear picture of how the supposedly smallest particles of matter called atoms could be put together to form the various familiar substances found in nature.

Abstract

The tradition of growing of flowers is age old. The flowers have travelled from the bowl of prayers to gardens to commercial sector for revenue. The quality concerned world demands for round the year production and supply of quality produce which can only be possible under controlled environment production. A range of location specific and crop specific infrastructures are being commercially used for production of planting material and flowers. General and crop specific guidelines for trade of cut flowers are available which the producers and policy makers must know for successful promotion of export of cut flowers from the country. The producer can also use practical methods for vase life study of their produce which is of great relevance in cut flower trade.

Keywords: Protected floriculture, trade, crop specific guidelines, export, cut flower

Introduction

Indian floriculture industry is shifting from traditional flowers to cut flowers for export purpose. The liberalized economy has given an impetus to Indian entrepreneurs for establishing export oriented units (EOUs) under controlled climatic conditions. The wide variations in agro climatic conditions in India permit us to grow various types of tropical and subtropical flowers. Though such plants grow successfully in open conditions without cover, they fail to meet the quality requirements of being blemish free. High quality ornamental plants meant for export should be scientifically grown only in plastic, glass or fibre glass greenhouses or at least under partial cover. Though initial investment is high in protected cultivation, the products in them will obtain far more attractive prices.

Abstract

Domestic market both for cut flowers as well as loose flowers have increased significantly owing to rapid urbanization, changes in social attitude, increase in income level and the increasing habit of ‘saying it with flowers’. The per capita consumption of flowers is increasingly growing up due to which the production has been increased and non-traditional areas have emerged as important players in floricultural production. In this scenario of intensive production system, protected cultivation can be a viable option. Protected cultivation offers unique opportunities to produce high quality flowers round the year and insulate from weather vagaries thus, reduceing risk from the climatic variations. Protected structure comprises of high cost, medium cost and low cost polyhouses and each structure needs specific varieties and technologies to achieve maximum yield. Hence, breeding program should be based on structure and climate as it has been observed that varieties bred in Northern hemisphere under high cost greenhouses are not performing alike in medium and low cost polyhouses of Southern hemisphere. Breeding work in India has been carried out in wide range of floriculture crops. Breeding of many floricultural crops are in fact not always simple and straightforward due to polyploidy, complex ancestry involving one or more species, aneuploidy, and in some families self and cross sterility barriers, etc. It appears that breeders have vast opportunities to incorporate disease and insect screening and development of varieties for protected cultivation in routine breeding programs during the evaluation of seedlings. To develop varieties for such adversities, our research institutes should have enough infrastructures to carry out required research. In a few areas, protected cultivation has succeeded in India due to efforts of private companies and enterprising farmers. Recently, with greater efforts of ICAR a few public institutions have started breeding of flower varieties suited for protected cultivation.

Abstract

Floriculture is the fast emerging sector in horticulture sector and people are changing very fast from the traditional field crops to flowers because of high returns per unit of area and better price. The flowers are being used during all the occasions. Though the art of growing flowers is not new to India, large scale commercial cultivation and protected cultivation in polyhouses is relatively new in India. With the opening up of world market in the WTO regime, there is a free movement of floriculture products worldwide. India is having a better scope in future as there is a shift in trend towards tropical flowers and this can be gainfully exploited by countries like India with high amount of diversity in indigenous flora. The major flowers grown under protected cultivation are rose, chrysanthemum, gerbera, carnation and lilium. Even some of the flowers are location specific and made a dent on the state economy, the best examples are carnation in Himachal Pradesh and gerbera in Maharashtra. Now with market trend is changing and biotechnological tools must be exploited for the crop improvement to evolve novel varieties with desirable colour traits. The other major area of work is on protected cultivation of cut flowers which is coming up on a large scale and value addition in floriculture i.e. extraction of pigments, essential oils, pharmaceutical and nutraceutical compounds have emerged as frontline avenues in floriculture. We have many challenges ahead like trained HRD, quality planting material, technical knowhow, limited choice of the varieties and products in the market to compete in global market.

Abstract

Protected cultivation technology in black pepper and cardamom offers distinct advantages over conventional farming. Production of quality planting materials irrespective of the season was made possible. Such propagating materials can be well maintained under polyhouse, irrespective of the seasons and can be used judiciously for replanting/ gap filling. In this era of climate change, protected cultivation assumes significance. In black pepper and cardamom, rapid multiplication techniques of planting materials were made possible. A novel idea of growing pepper, different from conventional system as “bush” that can be grown under potted and field conditions were also developed. Nutrition and water management studies could be undertaken with precision. In cardamom, quality planting material production and high quality capsule production are made possible all throughout the year by the adoption of protected cultivation. For optimizing production, prescriptions of fertilizers, using DRIS norms were developed for black pepper and cardamom based on critical soil and foliar nutrient concentrations. Typical deficiency symptoms of major and micro nutrients on black pepper were characterized to rectify the deficiency. Technology for propagation and cultivation of bush pepper in pots, under protected cultivation was also developed and popularized. Technology for using organic manures, non edible oil cakes, biofertilizers towards production of high quality zero defect black pepper and cardamom was also developed and popularized.

Protected cultivation is a specialized agricultural system in which a certain control of the soil–climate ecosystem is exercised modifying its conditions (soil, temperature, solar radiation, wind, humidity and air composition). Plants are cultivated by means of these techniques modifying their natural environment to prolong the harvesting period, alter the conventional cropping cycles, increase yields, improve product quality, stabilize production and provide products when open field cultivation is limited (Wittwer and Castilla, 1995). It is the most contemporary approach to produce mainly, horticultural crops qualitatively and quantitatively and has spread extensively the world over in the last few decades. Protected cultivation also known as controlled environment agriculture (CEA) is highly productive, conservative of water and land and also protective of the environment (Jensen, 2002). Protected cultivation is now becoming popular in Kerala experiencing humid tropical climate with the adoption of locally suitable green house technologies.

Protected cultivation has rapidly expanded in many regions across the globe as early as 1960, when plastics were introduced/used in agriculture and subsequently during 1970’s, when the rise in oil prices resulted in increase of energy costs. About 115 countries in the world are into greenhouse vegetable production commercially (Sabir and Singh, 2013). The world scenario shows the area under protected cultivation to be nearly 6,23,302 ha. while total estimated world greenhouse vegetable production area is 4,02,981 ha. Of the total world greenhouse vegetable area, soilless/hydroponic culture systems account for 95,000 ha (Hickman, 2011).

The advent of protected cultivation technology in India materialized during the early nineties, post globalization. In India, area under protected cultivation is presently around 25,000 ha while the greenhouse vegetable cultivation area is about 2,000 ha. Faced with constraints of land holdings, rapid urbanization, declining crop production, declining biodiversity and ever increasing population, demand for food, especially vegetables has increased manifold and protected cultivation has offered a new dimension to produce more in a limited area. Today Dutch protected cultivation is one of the most intensive farming systems in the world with high levels of output by using the latest technologies (Goncharova, 2004).

Abstract

Greenhouse vegetable cultivation is gaining popularity for reasons such as high productivity of quality produce round the year with enhanced input use efficiency. As agriculture has a major share in our economy and if India has to emerge as an economic power in the world, the productivity should substantially increase from the present levels. We need a new and effective technology which can constantly improve the productivity, profitability and sustainability of our major farming systems. One such technology is the green house vegetable production technology. At Indian Institute of Horticultural Research, Bangaluru, research on greenhouse vegetable production is in progress since the year 2000, resulting in the development of many technologies which have made possible to realize high yield levels in tomato, capsicum and cucurbits that are comparable to international standards of greenhouse productivity. Tomato and bell pepper yields have touched 300 tonnes and 200tonnes/ha/year, respectively and cucurbits 80 to 100 tonnes/ha/crop of 3 months. Vegetable cultivation in cost effective greenhouse is a technical reality in India, which is being adopted by resourceful farmers in and around big towns and cities as a peri-urban horticultural system. Such production systems have not only extended the growing season of vegetables and made their availability round the year but also opened the possibilities of growing new vegetables such as coloured capsicums, cherry tomatoes, seedless watermelons, icebox melons, sweet cucumbers, coloured cabbage, etc., besides tomato, cucumber, eggplant and climbing beans. Quality seedling production is one more important greenhouse activity in the present agricultural scenario as more and more F₁ hybrids are being adopted by the farmers.

Abstract

Production of healthy and vigorous seedlings is the foremost crucial step for raising a successful vegetable crop. Now a days seedlings are raised in trays under controlled atmospheric conditions called as transplants. As soil substitutes, artificial media made of perlite, vermiculite and peat moss are commercially available. A good rooting medium should be light weight, well drained, well aerated, and soilless with or without starter solution or added nutrients and with good water and nutrient holding capacity. The media should be sterilized before use. Selection of trays for cell shape, size and number depends on the type and nature of crop. Most of the vegetable transplants are now being produced in hardened plastic or polystyrene containers. Only good quality certified seeds should be used in media filled trays after priming, pelleting, coating or other seed treatments as per the crop requirement. Germination chambers as insulated rooms to maintain suitable conditions over large period of time may also be used. Generally vegetable crops need fertilizer application after expansion of first true leaf. Young seedlings are managed carefully to avoid any toxicity while taking care of their nutrient management. Water requirement also depends on growth stage and variation in weather conditions. Other seedling management practices include shading, thinning, weeding, disease/pest control, hardening off and subsequent transplanting. Containerized greenhouse plants can be grown using the conventional “rail” (or rack) system or the “float” system. Shipping factors such as mechanical injury, environmental conditions and length of storage affect plant vigour and establishments. IPM (integrated pest management) offers a practical way to effectively manage pests on vegetable bedding and transplants.

Abstract

High altitudes may be cold and humid or cold or arid ones making the requirements of protected cultivation entirely different in both the conditions. The present chapter is based on the environmental conditions existing in Leh region. Near sub-zero temperature with snow in higher altitudes makes vegetable production tough without use of techniques of protected cultivation. Protected cultivation has witnessed gradual developments from riverbed cultivation practices to use of several types of plastics (PP, PE, PVC etc.) and UV stabilized polythene sheets. Area under protected cultivation is spread worldwide mainly in countries like Holland, Spain, Isaral, China , Japan etc. Protected cultivation technology provides favorable climate for production of vegetable &/or their seedlings of superior quality even in the extreme adverse climate outside. Such structure exploits solar thermal energy to improve photosynthetic efficiency of the plants grown inside. This green house effect is very helpful in winters at high altitudes. Similarly, some modifications in these structures are needed to low the temperature during summers. A number of advantages with some limitations can be listed that are associated with the protected cultivation. At high altitudes, three methods viz. Polyhouse/Greenhouse /Net /shaded house, Low tunnels or row covers and plastic mulching can be used. Polyhouse is a framed structure with 200 micron UV stabilized low density cladding forming a greenhouse effect. Underground trench type polyhouse can also be made with polyethylene supported on wooden poles or GI pipes. Though a combination of above two known as polyench was found performing better in Ladhak area. Low tunnels or row cover use transparent plastic films or net over low hoops to cover rows of plants. Mulching is covering the soil around plants to conserve soil moisture, temperature, preventing weeds etc. using transparent and black plastics of 10-25micron thickness. Double colored plastic mulches are being tested for different crops and different seasons. In arid high altitudes, DRDO (through DIHAR, Leh) has worked extensively on protected cultivation and developed production technologies in the service of nation. Its contribution includes making possible the production of nursery, cucurbits and several other vegetables and their seeds in sub zero climatic conditions. Now, there is a need to develop more area specific, more appropriate, efficient and economic protection structures. Simultaneous development of tools, machinery and vegetable varieties suitable for use in protected conditions are among the major aspects of future work to be done in this field.

Abstract

Vegetables are health capsules, being the chief source of vitamins and minerals besides providing other dietary elements like carbohydrates, proteins and even fat and enzymes to some extent, antioxidants and fibre. Though India is the second largest vegetable producer (147 million tones in 2012) in the world, per capita supply and consumption of vegetables in India is very low (160 g day ^-1). It is now realized that the problems of satisfying hunger and nutrition are much beyond the realm of food crops alone and therefore, to supplement and balance our diet, more vegetables are to be included. Vegetables not only provide nutritional security in rural areas but also financial security to small and marginal land holders growing vegetables in the hinterlands of urban markets. Commercialization of vegetable production is the scene of the day as they are money spinners in domestic markets and dollar earners in global markets. To compete in the domestic and global market and for year round supply of quality produce, protected or greenhouse cultivation of vegetables is imperative. Water and nutrients are the top most growth and production inputs in any crop cultivation and vegetables are no exception to this. In order to get the potential yields with matching quality of vegetables grown under protected cultivation, the best of the management strategies to supply water and nutrients is needed. In this direction, drip fertigation is the best option for efficient supply of irrigation water and fertilizer nutrients for greenhouse grown vegetable crops. The studies carried in different parts of the world have clearly indicated that fertigation technology resulted in substantial yield increase with marked enhancement of water and nutrient productivity.

Abstract

Space, water and labour have become limiting factors in vegetable production. Moreover, production of off-season vegetables during period of demand fetches better returns. Vegetable forcing for year round production has become a necessity in urban and peri-urban olericulture. With use of pesticides, fungicides, weedicides and chemical fertilizers, health hazards have become visible. Being treated as a field crop, vegetables are exposed to vagaries of weather and floods and droughts take heavy toll. Research on protected cultivation in India is limited but for attempts by private seed companies and enterprising farmers in Karnataka, Maharashtra, Haryana and Punjab. More emphasis is given to tomato, cucumber, capsicum, lettuce and beans. Breeding for varieties suited for protected cultivation is a recent innovation in public sector laboratories. Now there are parthenocarpic cucumbers, tomatoes and capsicum especially to suit protected cultivation. The first four vegetable varieties were developed and released by Uttarakhand State Varieties Release Committee for Horticultural Crops during 2011. These varieties namely Pant Polyhouse Hybrid Tomato -1 , Pant Polyhouse Tomato -2 in tomato and Pant Parthenocarpic cucumber -2 and Pant Parthenocarpic Cucumber -3 in cucumber. These varieties were delivered to ployhouse farmers cross the country.

Abstract

Keeping in view the increasing demand of off-season and high value vegetables in several big cities of the country, there is an urgent need for diversification from the traditional agriculture by production of high value vegetable crops under different protected conditions for increasing their productivity and quality not only for getting high returns but in a Horti-Business / Veggie-business model. Nursery raising under protected cultivation is highly suitable for such Horti-business model or can be adopted as an agri entrepreneur business in major vegetable growing areas of the country by unemployed youths who are graduates in agriculture or post graduates in horticulture. Low cost protected technologies like plastic low tunnels or walk in tunnels, shade net houses can be used for off season vegetable cultivation for getting high returns. Similarly, insect proof net houses can be used on a large scale for safe vegetable cultivation by way of minimizing the use of pesticides in vegetable cultivation and virus free quality seed production in large number of vegetables in a horti-business model. Some of the technologies like low pressure drip irrigation and low cost nursery raising technology can also be replicated in other parts of the country even among the resource poor and tribal farmers.