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Maize (Zea mays L.), the “Queen of Cereals” is one of the most important highly evolved coarse cereal crop originated at Mexico. This is most widely distributed crop of the world cultivated predominantly in tropics and sub-tropics right from sea level to 4000 m altitude as irrigated or rainfed crop. The demand for maize as an animal feed will continue to grow faster than the demand for its use as a human food, particularly in Asia, where, doubling of production is expected from the present level of 165 m t to almost 400 mt.

Maize (Zea mays L.) is the third most important crop of country after rice and wheat and is cultivated round the year. Its grain is used as feed, food and industrial raw material. Enormous progress has been made during last six decades to enhance yield potential through genetic improvement and alleviate effects due to various biotic and abiotic-stresses. In India, it is an important crop not only in terms of acreage but also in context to its versatility for adoption under wide range of agro-climatic conditions. Of the different forms used for human consumption, 45% is consumed as staple food in various forms viz., bread, biscuits, cookies or transformed into corn flakes, soups, fresh-roasted sweets, boiled cobs and vegetables etc. Maize grain is main ration for poultry birds while forage maize is used as fresh or dry fodder for dairy industries. In Rajasthan maize occupies 0.89 m ha area with an annual production of 1.55 mt and productivity of 1.74 t/ha (Govt of Rajasthan, 2015). Being major Kharif crop in Rajasthan, the productivity levels of maize are still below the national average and farmers are not getting better economic returns. However, profitability can be accelerated further by growing recently popular speciality corns.

Maize ranks fourth after rice, wheat and bajara with respect to area and production, and grown on 4.23 lakh ha average with 6.72 lakh tones production and yield 1589 kg/ha in the Gujarat (2014-15). The state has 38.0% lower than national yield. It mainly grown in Panchmahal, Dahod, Mahisagar, Vadodara, Chhota Udepur, Kheda, Sabarkantha, Banaskantha and Aravali districts as rainfed Kharif and irrigated winter/Rabi crop for food, feed and industrial raw materials.

It is staple food and feed of tribal and grown as sole and intercrops with pigeon pea, black gram and soybean in Kharif season. The white and yellow flints to semi-flint maize are preferred to prepare bread and other food preparations

The state of Madhya Pradesh is one of the high profile maize growing state of the country cultivating maize in about 11.32 lakh hectare area which is ~12% of the total maize area of the country having 90-95% of total maize area having rainfed. Madhya Pradesh is situated in heart of India between 17°-26° N latitudes and 74°-84° E Longitude. The rainfall in maize growing belt varies from 800 to 1600 mm. Due to erratic and uneven rainfall in the state, the production and productivity of maize fluctuates every year. Maize cultivation in the area is associated with resource poor tribal farmers. As the demand for maize is growing globally due to its multiple uses for food, feed and industrial uses, we need to produce more from same or even less resources, which can be achieved through targeting technologies in potential regions.

Besides, monsoon crop due to mild winter conditions the climate allows the cultivation of maize during winter successfully under assured irrigation conditions. At present about 50 thousand ha area is under Rabi cultivation with high productivity levels as compared to monsoon crop. However, the major area increase was achieved during past few years mainly due to adoption of hybrids and shift in acreage under non-traditional areas, replacing soybean crop on farmers field. Uncertain climatic conditions and more disease and pest problem lead farmers to adopt maize in place of soybean.

The trends in area production and productivity of maize in Madhya Pradesh has shown a remarkable increase during four decades. During 1966-67 the maize acreage in the state was very less (5.59 lakh ha) that has grown up by 11.32 lakh ha in 2014-15. Moreover, the productivity also increased dramatically from mere 811 kg/ha during 1966-67 to 1513kg/ha in 2014-15.

Maize (Zea mays L.) is the third most important grain crop in India after rice and wheat with respect to area and production. It has wide ecological adaptability and is grown in almost all parts of the country extending from extreme semi-arid to sub-humid and humid regions. The crop is also popular in low and mid-hill areas of Western and North Eastern regions. It has the highest yield potential and used as human food, animal feed and as a source of large number of industrial by-products. Hence, it is called as “Queen of cereals”. In India, about 59% of the total production is used as feed, while the remaining is used as industrial raw material (17%), food (10%), exports (10%), and other purposes (4%).

Tamil Nadu has a total geographical area of 13 million hectares with a coastal line of 922 km and is endowed with 3 per cent of water resources of the country. Out of 13 million hectares of geographical area, the cultivable area in Tamil Nadu is around 7 million hectares and 55 per cent of which is dryland. The State has gross irrigated area of 33.94 lakh ha out of which 79% is under food crops and 21% is under non-food crops. In Tamil Nadu, maize was grown in an area of 0.14 lakh ha during 1970-71 with the annual production of 0.16 lakh tonnes, mainly concentrated in Tanjore, Pudukkottai and Trichy districts. Due to rapid increase in the demand of maize for poultry and animal feed, industrial uses and introduction of high yielding varieties and hybrids, the area under maize has gone up to 3.8 lakh ha with the production of 22.45 lakh tonnes during 2013-14. The major maize growing districts are Perambalur, Tuticorin, Dindigul, Erode, Karur, Ariyalur, Salem and Southern districts of Tamil Nadu. The demand and production of maize is increasing more rapidly as compared to other major commodities. It is estimated that the demand for maize will continue to increase in coming days (Yadav et al., 2016). Thus, in the next 10 years there is a necessity and opportunity for doubling India’s maize production from the current level of approximately 26 million MT.

Maize production in India has been dominated by erstwhile Andhra Pradesh and Karnataka which together contribute around 38 per cent of the total maize production of the country. Erstwhile Andhra Pradesh has achieved the highest mean yield of 4441 kg/ha in the country during the last decade (2001-02 to 2010-11) by surpassing Karnataka which had the highest productivity in the country, earlier. The main reason for achieving the highest productivity in the country was due to adoption of improved production technology along with 100% area grown under hybrids. In Telangana, maize is the third most important crop after rice and cotton. It is cultivated in 5.74 lakh hectares, predominantly in Kharif season (4.54 lakh ha), with a productivity of 3.69 t/ha (2015-16).

Trends in maize area, production and productivity in the state (1950 to 2016)

The erstwhile Andhra Pradesh (including Telangana) is the non-traditional maize growing state. But, the climate of the state is very favorable for the crop and hence maize can be grown in any season in the state. However, it is mainly grown as a rainfed crop during monsoon season, concentrated in Telangana. The trends in area, production and productivity of maize in erstwhile Andhra Pradesh have shown a remarkable increase during the past six decades. During 1955-56, the maize acreage in the state was very less (1.89 lakh ha), which has been up by 5.3 times to the present (2014-15) level of 9.95 lakh hectares. The production has also increased dramatically from merely 1.14 lakh tonnes during 1955-56 to 42.36 lakh tones during 2014-15, which is nearly 37 times higher. Similarly, the productivity of maize in the state was merely 601 kg/ha during 1955-56, which has been increased to 4257 kg/ha during 2014-15 (Fig. 1).

Karnataka is India’s eighth largest state in geographical area covering 1.92 lakh sq km and accounting for 6.3% of the geographical area of the country. As per the population Census 2011, agriculture supports 13.74 million workers, of which 23.61 per cent are cultivators and 25.67% agricultural workers. A total of 123,100 km² of land is cultivated in Karnataka constituting 64.6% of the total geographical area of the state (Table 1). Of the total cultivated area in the state, about 33.0% is covered by cereals, 42% by pulses and 19% by oilseeds and 6.0% by commercial crops (Savitha and Kunnal, 2015). Agriculture employs more than 60% of Karnataka’s workforce. The large portion of agricultural land in the state is exposed to the vagaries of monsoon with severe agro-climatic and resource constraints.

Maharashtra is the third largest state in terms of area in the country located in the north-centre of peninsular India. It links the southern part of the northern plains to the southern peninsula. Maharashtra occupies the western and central part of the country with total 3.08 lakh sq. km geographical area and has a long coastline stretching nearly 720 kilometers along the ARabian Sea. The prominent physical trait of the state is its Plateau character, which has up to 1350 meters high altitude. Physiographically this state may be divided into three natural divisions-the coastal strip (the Konkan), the Sahyadri or the Western Ghats and the Plateau. The Sahyadri mountain ranges provide a physical backbone to the state on the west, while the Satpuda hills along the north and Bhamragad-Chiroli-Gaikhuri ranges on the east serve as its natural borders. It has a geographical area of 307713 sq. km and is bounded by north latitude 15°40’ and 22°00’ and east longitudes 72°30’ and 80°30’.

NBSS & LUP has divided the state into 356 soil mapping units and published a map of the soils of Maharashtra. It has broadly categorized as soils of Konkan coast, soils of Western Ghats, soils of upper Maharashtra, soils of lower Maharashtra. The soil status of Maharashtra is residual, derived from the underlying basalts. In the semi-dry Plateau, the regur (black-cotton soil) is clayey, rich in iron and moisture-retentive, though poor in nitrogen and organic matter. The rainy Konkan and the Sahyadri Range, the same basalts give rise to the brick-red laterites, which are productive under a forest cover, but readily stripped into a sterile varkas when devoid of vegetative cover. The soil in the Deccan Plateau is made up of black basalt soil. This type of soil is rich in humus. The soil is commonly known as the black cotton soil because it is best suited for the cultivation of cotton. The volcanic action which had taken place in the Deccan region has given rise to the soil texture and composition. These igneous rocks break down into the black soil which is very fertile. The Wardha-Waliganga river valley has old crystalline rocks and saline soils which make the soil infertile. This type of soil has a natural resistance to wind and water erosion because it is rich in iron and granular in structure. A very important advantage of this type of soil is that it can retain moisture. This makes the soil very reactive to irrigation.

Maize is presently the crop with growing importance in the state. Earlier it was primarily grown for human consumption only. In view of rapidly increasing demand of poultry feeds and fodder in Assam presently it has more use in some small industries. It is the raw material for most of the feed industries. Presently the crop has state acreage of 27953 hectare and production of 93179 tonnes with a productivity of 3333 kg/ha (2014-15).

While most other states in India are gradually moving away from their traditional agriculture based economy toward industry or service oriented economy, Assam is still predominantely dependent on the agricultural sector. While the sociopolitical problems afflicting the state since the last few decades are partly to blame for a lack of conducive environment for economic development of the state, particularly in industry or service oriented areas, there are various economic reasons (e.g. fragmented land) responsible for the lagging agricultural sector in the state. Economy of Assam is fundamentally based on agriculture. Over 70% of the state’s population relies on agriculture as farmers, agricultural laborers, or both for their livelihood.

Assam produces both food and cash crops. The principal food crops produced in the state are rice (paddy), maize (corn), pulses, potato, wheat, etc., while the principal cash crops are tea, jute, oilseeds, sugarcane, cotton, and tobacco. Although rice is the most important and staple crop of Assam, its productivity over the years has not increased while other crops have seen a slight rise in both productivity and acreage.

Maize is the only cereal crop which is being used as human food, animal feed and as a source of large number of industrial products. In Odisha traditionally maize is a Kharif season crop and second most important crop next to paddy during Kharif season in terms of both area and production. The Rabi maize is cultivated under irrigated condition, and accounts only 7% of total area and production of the State. While only 24% of the Kharif maize area have irrigation facilities. Irrespective of the season, it is that is the fourth most important food grain crop with respect to area in the state which is next to rice, mungbean and urdbean. Even though maize is grown as a sole crop in the state but, some farmers are also adopting maize based inter-cropping and the major recommended/adopted inter-crops are arhar, cowpea, yam, runner bean, greengram and blackgram. The comparative analysis of compound annual growth rate (CAGR) of area, production and yield of the major crops is the state was done for the years 2004-05 to 2013-14. The CAGR study of major crops revealed that no other major crop including rice has the impressive growth rate a like maize in the state (Fig. 1).

West Bengal is the fifth largest state in terms of (GSDP) Gross State Domestic Product after Maharastra, UP, TN and AP and is the third largest contributor in agriculture sector of real GDP. West Bengal has 3% of India land mass and 8% population with population density of 1029 per km².

Agriculture accounts for about 17% (2013-14) GSDP and provides employment to over 55% of workers. About 64% of the geographical area of West Bengal is under cultivation. There is little scope for further increase the current cultivable area. Because it is difficult to maintain the growth rate in the absence of adequate infrastructure support, crop diversification and market access.

Food production remained stagnant as the green revolution by-passed the state. However, there has been a significant increase in food production since 1980’s and the state is now one of the few Indian states with a surplus in food production, producing nearly 20% of the rice and 33% of potato. Agriculture accounts the largest share of the labour force. Rice, potato, jute, sugarcane and wheat are the top five crops of the state, while other major food crops include maize, pulses, oilseeds, wheat, barley and vegetables. In recent years, significant changes have occurred in maize production and utilization due to increasing commercial orientation of maize crop and rising demand for diversified end users, specially for feed and industrial uses. A sizable number of districts in West Bengal have potential for growing winter maize. Though maize favourably responds to better crop management both in Kharif and Rabi season, the erratic rainfall pattern of the south-west monsoon comes in the way of timely field operations of Kharif season. In absence of any major environmental impediments in Rabi, the desired field operations can be planned and executed at the most desired time. Moreover, the various environmental factors including absence of any major disease and insect pests in this season, helps in realizing the better profits from every additional unit of monetary inputs. Hence, future of Rabi maize in West Bengal is bright.

Maize or corn (Zea mays L.) is second most important crop after rice in Jharkhand. Though considered as a Kharif season crop, it can be successfully grown in other two crop seasons viz., Rabi and zaid also as the climatic condition in Jharkhand is conducive for growth of the plants. Rabi maize has comparative advantage over Kharif maize due to low incidence of diseases and insect pests slow growth of weeds and crop does not have to suffer on account of heavy rainfall hence, higher yield potentiality could be realized from Rabi maize. In Jharkhand, the Kharif crops including the maize are grown as rainfed as the 80 to 85% of the annual rainfall takes place during June to September. The share of maize under irrigated condition is restricted to only 15 to 18% of the total cropped area. Maize is not only an important source of nutrient to the human beings but also constitutes a basic component of animal and poultry feed. Here, farmers grow maize mainly for green cobs as cash crop whereas the grains are to be used for human consumption as well as for animals and poultry feed. The cultivation of the specialty corns like baby corn, sweet corn and popcorn is still in its infancy in Jharkhand and hence, large scale cultivation of specialty corn in the state will take some more time. Establishment of food processing unit in the state is at the nascent stage. However, the Government of India is implementing a Mega Food Park in Getalsud Industrial Area of Ranchi district in Jharkhand. The establishment of this mega food park is expected to give a significant boost to the food processing sector in Jharkhand.

Bihar is an important maize growing state in India after Karnataka, Andhra Pradesh, Telangana, Rajasthan and Maharashtra, where it is cultivated during all season. However, the yield of maize is much higher during Rabi and summer seasons than the Kharif. Due to climate change and other factors, the yield of maize is likely to further decline during the Kharif season. However, the cultivation of maize in Bihar during the Rabi season will be much more profitable as compared to wheat due to rise in temperature. There is need to develop maize varieties which can with stand biotic and abiotic due to changing climate factors.

Decadal trends of maize area, production and stresses yield in the Bihar from 1950–2015.

Chhattisgarh, the 26^th state of the Indian Union came into existence on November 1^st, 2000. The state is geographically situated in the central part of India, between the latitudes of 17° 46' N - 24° 5' N and the longitudes of 80° 15' E - 84° 20' E. Its proximate position with the Tropic of Cancer has a major influence on its climate. The total geographical area is around 137.90 lakh ha of which cultivable land area is 46.77 lakh ha and forest land area is 63.53 lakh ha with more than 2.55 crore population. In Chhattisgarh region about 22% of net cropped area was under irrigation. About 80 percent of the population in the state is engaged in agriculture and 43 percent of the entire arable land is under cultivation. Paddy is the principal crop and the central plains of Chhattisgarh are known as rice bowl of central India. Other major crops are coarse grains, wheat, maize, groundnut, pulses and oilseeds.

Importance of Maize in Chhattisgarh

Earlier maize was mainly cultivated in Surguja and Bastar division of Chhattisgarh but now it is emerging as main cash crop in entire Chhattisgarh state. There had been an increase of 20 per cent in maize crop acreage in Chhattisgarh during the past 10 years. Now the farmers of the area are cultivating maize in lines, applying atrazin weedicide, full dose of chemical fertilizers, etc. They are willing to buy the hybrid seed for cultivation from the market and taking maize as green cob and also utilizing as green fodder. Maize threshers have been purchased by some farmers in the region which is an indicative of large maize production.

For industrial utilization of the maize Chhattisgarh state has “Raja Ram Maize Factory” in Rajnandgaon district. They are producing and supplying Maize starches, liquid glucose, dextrose mono hydrate, dextrin, maltose liquid, malto dextrin, maize oil, maize gluten, maize grit, maize husk etc. But most of the maize production is used as poultry feeds in the state. Traders purchase it directly from the farmers’ fields in the villages. It is also exported to the neighboring states either as grain or green cob. Around 10-15% is retained by the farmers for own consumption and seed purpose.

Uttar Pradesh, a fourth largest state of India geographically, where agriculture is a prime occupation and this is the traditional maize growing state, accounts 7.7% of area and 5.4 percent of total maize production of the country with an average yield of 1791 kg/ha (IIMR Annual Progress Report, Kharif Maize 2015). Maize is mainly taken as a Kharif crop but, gradually Rabi maize is gaining popularity with the availability of high yielding varieties and advanced production technologies. The rice, wheat, potato, sugarcane based cropping is more popular, and maize is given a moderate priority. The current level of growth in productivity definitely fall short to meet the demand of rapidly growing population even it may increase the poverty, unless vigorous measures are taken to accelerate yield, growth, employment generation, increasing the income of farming family and ultimately targeting for the sustainable climate resilient maize production.

Maize is mainly used as a staple food and quality feed for animals. In addition to that it also serves as a basic raw material for several industries like, starch, oil, protein, alcoholic beverages, food sweeteners, pharmaceuticals, cosmetic, textile, gum, package, paper etc. A major portion of the maize produce is directly consumed as a food in the form of boiled or roasted green ears, chapattis, porridges of various forms, popcorn, cornflakes etc. and as livestock feed viz., cattle, poultry and piggery both in

the form of grain and fodder The central rachis of maize cob, to which the grains are attached remains as an agricultural waste after threshing, has many important agricultural and industrial uses. It is approximately 15 to 18% of the total ear weight and contains 35% cellulose, 40% pentose and 15% lignin (used as a raw material in cardboards). Its uses in agriculture includes as a litter for poultry and as a soil conditioner.

Maize is one of the most important food, feed, fodder and industrial crop in Haryana and is cultivated in all the three seasons (Kharif, Rabi and spring). It was cultivated on 6 thousand hectares in Kharif season with average productivity of 2.83t/ha during 2015-16. The maize is also increasing in spring season which was grown on ~ 7 thousands hectare with productivity of 4.5t/ ha. The specialty corn (baby corn and sweet corn) is also grown in >2 thousand hectare area of Haryana in national capital region. The demand of maize is increasing every year due to growth in poultry industry and expansion of maize based industries. There is a good scope of cultivation of specialty types of corn (baby corn, quality protein maize and sweet corn) in Haryana as it is very near to national capital, Delhi. The cultivation of specialty corn and its value addition by establishing

Maize is one of the most important cereal crops of the world. Being a C₄ plant, it is physiologically more efficient than rice, wheat and other important cereal crops which belong to C₃ category. In Punjab, traditionally, maize is grown during Kharif season but from last few years the area under spring maize is increasing because its cultivation is highly profitable and commercially viable after harvesting of potato crop. No doubt, Punjab has been the leading state in contributing to the national food security but simultaneously paddy-wheat rotation resulted in depletion of underground water, deterioration in soil health and environmental pollution. These problems need to be addressed for the sustainability of these natural resources and at the same time meeting the food grain production for the ever-increasing human population. Under such circumstances, maize crop is a viable alternative to replace some area occupied by rice and can help in breaking rice–wheat dominant cropping pattern in the state. Promising maize hybrids possessing high grain yield potential and offering comparable economic returns to the farmers are available with Punjab Agricultural University as well as with the private sector.

In Punjab, maize is commonly used in the form of chapatis, boiled or roasted green cob, breakfast food like cornflakes, popped grains etc. Maize chapatis are used as a delicacy with saag. The high carotene content of yellow grained maize is considered very useful in imparting yellow colour to egg yolk. Therefore, a substantial quantity of maize grain is utilized as an important ingredient of animal/ poultry feed industry. The use of maize grains for such purposes is going to increase as poultry and dairy industries are expanding. Maize plant is extensively used as green as well as dry fodder. The digestibility of maize fodder is better than sorghum, bajra and other non- legume forage crops. Maize plant does not have any anti quality factor hence can be fed to cattle at any stage. Maize can be utilized as an industrial raw material for number of industries viz., starch, ethanol, rubber, paper, cosmetics and pharmaceuticals etc. Quality Protein Maize (QPM) can be promoted for nutritional security of poor masses whereas pop corn, baby corn and sweet corn can help in increasing the farm income due to high market value. In Punjab, major industries which are utilizing maize are The Sukhjit Starch & Chemical Limited, Kapurthala, and M/s Field Fresh Food Pvt. Ltd, Ladhowal, Ludhiana.

Agriculture is the predominant sector in the economy of Jammu and Kashmir. Directly and indirectly, it supports about 80 per cent of the population besides contributing nearly 60 per cent of the state revenue. The total geographical area of the state is nearly 22.2 million hectare and population of 12.5 million, which is approximately 1.04% of the national total. The J&K is divided into three agro-climatic zones: Cold arid desert areas of Ladakh, temperate Kashmir Valley and the humid sub-tropical region of Jammu. Each has its own specific geo-climatic condition which determines the cropping pattern and productivity profile.

In Jammu province, a small portion of the land lies in the plains along the borders of Punjab while the rest of the area is hilly, dominates both in maize and wheat production. About 67 per cent of the area is under maize and wheat production with the production of 21.25q/ha maize and 15.36 q/ha wheat. This region contributes 79.56 per cent and 95.69 per cent of total production of these two cereals respectively. Even though the yield is not high, the region makes appreciable contribution to the cereals production.

The second agro-climatic zone Kashmir is also known as ‘cultivator’s paradise’. The region practically depends on irrigation, which is easily available. A large area of level land has alluvial soil. Extensive elevated plateaus of the alluvial or lacustrine material (locally called Karewas) also exist in the Kashmir valley. These Karewas are productive only in the face of sufficient rainfall or adequate irrigation facilities. Rice is the chief crop of this zone, followed by maize, oat, barley and wheat.

Ladakh zone is endowed with bare rocky mountains and bare gravel slopes. Villages are located near pockets of land with level ground and irrigation facilities, where cultivation is viable. In this region, barley is the major cereal crop followed by summer wheat. Millets and wheat rank second in importance and are grown in the warmer belt of the region.

Maize (Zea mays L.) is one of the most versatile crops having the highest genetic yield potential among cereals and wider adaptability under varied agro-climatic conditions rightly earning it the name of ‘the queen of cereals’. Maize is cultivated in all agricultural areas around the world and is an economically significant crop for all human population. It is grown from 58⁰ L north to 40⁰ L south and extends from the sea level up to an altitude of above 3,800 m; covering regions with rainfall varying from 250 to 10,000 mm (Hallauer and Miranda, 1988). Globally, maize occupies an area of about 184.0 million ha with production of 1065 million tons and productivity of 55.2 q/ha (FAOSTAT, 2014). It is the third most important cereal crop and a major source of energy, protein and other nutrients for human and livestock in the world (Jompuk et al., 2011). India is the second most important maize growing country in Asia, and now ranks as the world’s fifth largest consumer of maize. It is an important cereal crop in India covering an area of 9.42 million ha with a production of 24.35 million tonnes and productivity 25.83 q/ha (Anonymous, 2015). Maize is cultivated in the country throughout the year mostly during rainy or Kharif season (June to September, 80%) followed by winter or Rabi (November to April,18%) and spring (February to May, 2%) for various purposes including grain, fodder, green cobs, sweet corn, baby corn and popcorn.

Maize is an important crop of Uttarakhand and is cultivated in about 22 thousand ha in both hills and plains. The crop is grown for food, feed and fodder and forms an integral constituent of all major cropping systems prevalent in the state. Kharif (June-September) is the main grown season in the hills, whereas in the foothills and tarai plains, the crop is grown during zaid (Feb-May) as well. The crop is grown broadly for two different end products – grain and green ears. In areas where maize forms staple diet, the crop is grown for grain, whereas in areas adjoining/en route popular tourist destinations and towns, the crop is grown mainly for green ears. The crop is also gaining importance as an industrial crops following establishment of maize processing industry in the state.

The major maize growing districts of the state are Dehradun, Nainital, Pithoragarh, Pauri, Tehri and Almora (Fig. 1), which together comprise about 90% of total

An electron impringing on a solid surface may be scattered once, several times, or never. When an incident electron beam bombard atoms of the sample, secondary electrons (SEs) and backscattered electrons (BSEs) emerge from the sample surface. Multiple scatterings occur if the dimension of the material is greater than approximately twice the mean free path of the electrons. This scattering may be elastic or inelastic. A pear shaped volume (interaction volume) is formed as shown in Fig. 1 and this volume of excitation increases with increase in the beam voltage (electron energy) and decreases with the increasing specimen density (ion atomic number).