All About Rice


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All About Rice

  1. 1. Rice (Oryza sativa Rice Rice is a plant of Asian origin. The earliest record of rice in the world comes from Non Nok Tha in Thailand, where it dates back to 3500 BC. First evidence of Oryza sativa (Scientific name of rice) is found in North Bihar dated to 2000-2300 BC as well as in Hastinapur dates back to 100-800 BC (Randhawa, 1980). No wonder 90% of the world?s area under rice is in Asia and also about 90 percent of world rice is produced and consumed in Asia. In 7 countries of Asia, namely, Bangladesh, Cambodia, Laos, Myanmar, SriLanka and Vietnam, 90% of people are rice eaters, while in 6 other countries, namely, Indonesia, Japan, Korea Republic, Taiwan and Thailand, the percentage of rice eaters is 70-80 percent (De Datta, 1981). In India and China, which together hold about half the world’s rice area, about 63-65 percent people are rice eaters. Morphology Roots - Usually after sowing, rice seed gives out seminal roots out of the radicle. These are of temporary nature. The real functional roots are secondary adventitious that are produced from the lower nodes of the Culm (stem). The root system is fibrous and generally remains in the top 20 cm of soil in the case of transplanted rice. Stem - The culm (stem) is hollow and is made up of nodes and internodes. Each node bears a leaf and a bud, which may grow into a shoot or tiller. Primary tillers grow out of the main culm in alternate order. Emergence of secondary tillers from primary tiller also follows the same pattern. Tillering potential of rice varieties differs considerably. Hybrids have more profused tillering than the high yielding varieties. Tillering continues during the vegetative growth as well. Leaf - Each node of the culm bears a leaf. Each leaf consists of following parts. Leaf sheath - It originates form the node of a culm and many a times encloses it and sometimes even the next upper node and a part of the leaf sheath of the upper leaf. Leaf Blade- It is the upper expended part of the leaf and beings at node, where it is jointed with leaf sheath. At the joint there is a thich color. Auricles- These are hairy appendages at the base of the leaf blade. Ligule- It is a thin papery structure just above the auricle. It is generally shorter in length and remains erect at an angle. Flag Leaf- It is the uppermost leaf just below the panicle. It is generally shorter in length and remains erect at an angle. Panicle- the inflorescence of rice plant is born on terminal shoot and is known as panicle. It is determinate type and at maturity is droopy in nature. The extent to which the panicle and a part of the uppermost internode extend beyond the flag leaf decides upon the exsertion of the panicle and this character differs between varieties. Spikelet- A spikelets is the floral unit and consists of two sterile lemmas, a lemma, a palea and the flower. A brief description of the parts of spikelet?s follows: Lemma- It is a 5-nerved hardend bract with a filiform extension known as awn. Rice varieties may or may not have an awn. When they have an awn it is used in identifying them. Plea- It is a 3-nerved bract slightly narrower than lemma. Flower- It consists of 6 stamens with two-celled anthers and a pistil with one ovary and two stigmas. The pistil contains one ovule. Grain- Rice grain is the ripened ovary with lemma and plea firmly adhered to it. The lemma and palea with other smaller components form the hull and are removed in shelling rice for consumption. Rice Ecosystems- Rice is grown on a wide variety of climate-soil-hydrology regimes, which are grouped into various ?Rice ecosystems? or ?rice agro ecological zones?. In Indian rice is grown in all the states and union territories; from Srinagar in the north to Kanya Kumari in the south and from Arunachal in the east to Rajasthan in the west. A very broad based classification of rice environments or ecosystem used in India includes five rice ecosystems, namely, irrigated wet season, irrigated dry season, rainfed lowland, and rainfed upland and deepwater. Irrigated rice ecosystems- Irrigated rice ecosystems are those areas that have assured irrigation for one or more crops per year. About 57% of world areas under rice (about 43 million hectare) are under irrigation. Yield levels achieved are 4-7 I ha??-1 crop-1. There are three rice environments in this ecosystem, namely, irrigated with favorable temperature, irrigated with
  2. 2. unfavorable temperature- tropical zone and irrigated with unfourable temperature-temperature zone. Rainfed lowland rice ecosystems- The rainfed lowland ecosystem covers 38 million ha or 27 per cent of the rice area of the world. These are rice growing areas with bunded fields, where water depth does not exceed 50 mc for more than 10 consecutive days and the fields are inundated for at least part of the season. No water harvesting/conservation facilities are available on the farm and there is no irrigation water available. Upland rice ecosystems- This ecosystem covers about 18 million hectares of which 64 per cent is located in Asia, 25 per cent in Latin America and 11 per cent in Africa. These are rainfed rice areas with bunded or unbunded fields. Soils are well drained and therefore no surface water accumulates. Soils are low in fertility and weeds are a major constraint; in many regions soils tend to be acid. In the hilly regions mono-cropping of rice is practiced and it is detrimental to soil and environment. Deep water and tidal wet land rice ecosystems- About 13 million hectare are under deep water and tidal wetlands rice, mostly in South Asia. These are the regions where are the grows under rainfed dryland and shallow flooding conditions for 1-3 months and is then subjected to flooding with water depth of more than 50 cm for a month or longer. These areas are found in the river basins of Ganges and Brahmputra in India and Bangladesh, the Irrawaddy in Myanamar, the Mekong delta of Vietnam and Cambodia and the Chao Pharaya in Thailand. When water levels are over 100 cm, the crop is known as floating rice, while tidal wetlands occur where water levels are fluctuating and are influenced by tide such as in coastal belts. Rice Varieties- Rice is reported to have originated in Asia. It belongs to genus Oryza. Twenty species were enumerated by Roschewcz (1931) and twenty-three by Chatterjee (1948). Base on re-examination of specimens in major herbaria of the world, Tateka (1963-64) recognized twenty- two species of Oryza to be valid. Of these only two species are cultivated. Oryza glaberrima Steud. grown on limited acreage in a few African countries is gradually being and replaced by O. sativa L. due to its high yield potential and wider adaptability. The basic number ?n? of chromosomes of the genus Oryza is 12 (2n=24). Cultivated varieties of O. sativa are grouped into three ecotypes: indica, japonica and javanica. Indica are grown throughout the tropics and subtropics. These are characterized by all stature, weak stem, droopy leaves, high tillreing and do not respond to high input conditions (traditional varieties). Japonicas are limtied to temperate zone and subtropics. This group responds well to intensive crop management due to short stature, sturdy stem; narrow, erect and dark green leaves. Javanicas are grown mainly in part of Indonesia. They have fewer tillers, tall stature with sturdy stem, long panicles and long bold grains, in general. History of varietal improvement- Systematic varietal improvement began at Rice Research Station, Dhaka (Now in Bangladesh) in 1911 with pure line selections. Later on rice breeding and genetic research work was taken up at many other centers simultaneously. During Second World War large scale food shortage resulted in the establishment of Central Rice Research Institute (CRRI) at Cuttack in 1945. This was the center for indica-japonica hybridization programme. F2 seed of these crosses was made available to different research stations. ATD-27 (India), Mahsuri and Malinga (Malaysia) were developed under indica-japonica hybridization progarmmes. Tillage- Tillage is defined as breaking, stirring and conditioning of a soil for creating favorable condition for raising the crop. It needs to be done at the right time with the right implements. The major tillage effects are: Soil pulverization to facilitate root penetration and seeding emergence, cutting, incorporation and mixing of crop residues and vegetation into the soil for addition of humus and fertility to the soil, improvement in moisture retention capacity of the soil by breaking the hard pan and crust formed on soil surface, improvement in soil porosity and aeration and reduces weed problem. Tillage processes to achieve the above effects are generally accomplished in two stages, namely, primary and secondary tillage. Primary tillage is a initial breaking, ploughing and manipulating of soil from 15-90 cm depth of soil, whereas secondary tillage include seedbed preparation and interculture up to a depth of 15 cm. Primary tillage results in burying of weeds and stubbles whereas secondary tillage causes breaking of clods and mixing of crop reduces. After secondary tillage operation the land is ready for seeding. Tillage alone probably the most practical method of weed controls. However, tillage alone without use of weedicides can not eliminate weeds completely. Tillage operations vary according to cultivation practices, water availability, soil texture, topography and source of farm power and equipment used.
  3. 3. Deep Water and Floating Rice Cultivation- this method is the traditional method of rice cultivation in India. About 15% of world?s rice lands are subjected to annual floods and require deep water and floating rice cultures (De Datta, 1981). In this system tillage and seeding are done in dry soil before the onset of monsoon. Sometimes after seeding land is repeatedly ploughed to control timing of plant emergence the crop establishment and subsequent yield is poor in this system. Deep water rice genotypes grow rapidly when submerged upto 1 m depth of water. The floating rice grows rapidly (20 cm day-1) to resist deep water level that direct seeding of rice is superior to transplanting under flood prone lowland conditions. Upland Rice Cultivation- Dry seeding rice into dry soil is common in the area having scanty rainfall. Under this final land preparation is done with a harrow. The crop is sown by a conventional seeder. In this method labor requirement is low, yield is low, irrigation requirement is high and weed control is more difficult as compared to other methods of rice cultivation. However, under upland cultivation system soil structure after rice harvest is more favorable for next crop in comparison to wetland rice cultivation. Wetland Rice cultivation- Rice in India is traditionally grown as wet land crop. Land may be prepared dry or wet but crop is always raised under standing water. About 30% of the world?s rice is grown as rainfed low land and about 45% as irrigated lowland. Under wetland cultivation the soil is puddle prepared and the crop is either directly sown or transplanted Among different method of rice cultivation the highest yield is generally reported from wetland cultivation. Therefore a great emphasis has been on development of suitable set of practices and machinery for wetland rice cultivation. Paddy crop requires a large amount of water and hence to reduce irrigation requirement puddling is done in rice soils before sowing/transplanting. Seed bed preparation- In wetland cultivation either crop is directly sown on puddle prepared field or seedlings are raised in nursery and 2-3 weeks old seedlings are transplanted in the puddle prepared field under standing water. Nursery raising- Nursery for paddy is generally prepared in an area of 1/10th of the total area of the crop. Small plot are prepared to facilitate irrigation, weeding, care etc. three to four weeks old seedlings are uprooted and transplanted in puddle prepared field. Wet nursery is practiced in the area where irrigation is assured. In this method land is prepared by two ploughings, followed by 2-4 puddlings. Pre-germinated seeds are broadcast uniformly on a raised bed. To crop one hectare of area nursery is required to be grown in an area of 1000m2 and it requires 30-35 kg of seed. Seed is placed uniformly on the beds and is covered with a thin layer of soil or well decomposed compost. Irrigation is provided regularly. About to 3-4 weeks old seedlings are uprooted and transplanting in the puddle prepared field. Dry nursery is practiced in the area where water supply is not regular. The field is prepared by three to four ploughings and is leveled properly. The raised beds are prepared under dry conditions. Modified Dapog method is used to prepare nursery for use with mechanical transplanters. It includes the following steps: Collect the soil and sieve it through a 3-5 mm sieve, add FYM and 10 g each of N, P2O5 and K2O in each square meter area of the nursery, place a 50-60 gauge polyethylene sheet cover over the area. Place wooden frames having compartments equal to the size of the tray of the machine. Fill the prepare soil in these frames uniformly up to the top surface. Spread about 600 g m-2 of pre-germinated seeds in these compartments. Cover the seed by a thin layer of the soil and sprinkle water on it. Raised the seedlings for about 20 days. Ensure the nursery is free from weeds. Keep it wet without over flooding. Drain the water hours before in tray form by cutting along the boundries. The seedlings are now ready for machine transplanting. Field preparation- The seedbed under wetland cultivation is generally prepared as follows: 1. Plough the land with the help of a mouldboard plough/ disc plough/ rotavator/ disc harrow or cultivator. On animal operated farms ploughing is generally done by indigenous plough. However, use of mouldboard plough on animal operated farm helps in better preparation of soil. 2. The field is flooded with water and puddling is done with the help of mechanical puddlers. The land is then leveled properly with the help of a leveler. Seeding and transplanting- In wetland cultivation the crop is raised either by direct seeding or transplanting of seedlings. In direct seeding the seed is either broadcast or is sown by seeders. Minimizing weed growth is more critical in direct seeded rice as compared to transplanting because direct seeded rice does not get as much of a head start on weeds as transplanted rice.
  4. 4. Direct Seeding- Several studies have indicated that placement of sprouted seed in puddle soils, if managed well under weed free conditions, could give higher yield, which are comparable to transplanting but are superior to broadcasting in dry bed. Direct seeding thus offers a time efficient, low cast technology alternative to manual transplanting, particularly for areas having acute labour shortage during peak transplanting season. Direct seeding needs few rain free days after sowing or field should have excellent facilities for drainage of excess water in case of heavy rains immediately after sowing, to prevent submergence of seeds/young seedlings. Minimizing weed control is more critical for direct seeded rice than for transplanted rice. Transplanting- Transplanting of seeding, grown in nursery is done in puddle prepared field. In comparison to direct seeding, transplanting ensures higher yield due to reduced weed control requirement and increased availability of nutrients. Traditionally seedlings are grown in dry or wet type of nursery and two to three weeks old seedlings are manually transplanted. Agrotechniques- Rice growing season vary in different parts of India depending upon temperature, rainfall and other local climatic conditions. In general, there are three seasons of growing rice in India. These are aus or autumn rice, aman or winter rice and boro or spring/ summer rice. In the north-eastern and southern region, rice is grown in all the three season. In the eastern central region where winter temperatures are fairly low only one crop of rice is taken during kharif season. Time of sowing- Sowing of the dry and semi-dry crop should be in right time for getting maximum yield. Yield of the late sown crop has been found to be invariably low. Result of the earlier experiments conducted in various states revealed that earlier the sowing, better and higher was the yield. Sowing of deep water as well as aus paddy in Assam in April was found to be better than sowing in May. Seed Rate- Seed rate depends upon the duration and test weight of variety. Soil tilth, moisture content, and system of cultivation also determine the seed rate requirement. Optimum seed rate should be adopted for the direct seeded crop so that crop stand is neither too thick nor too thin. In general, a seed rate of 30-50 kg ha-1 is required for drilling, while 60-100 kg ha-1 is required for broadcasting. Nutrient Management- Adequate supply of essential plant nutrients is a must for getting good yield of rice; this is particularly true for high yielding varieties and hybrids. In India and for that matter in the entire Asia, fertilizer N mostly urea has received more attention (Prasad, 1998) than phosphorus and potassium fertilizers but balanced fertilization is the key. When we harvest a tone (100 kg) of rice grain, we remove from soil about 10-31 kg N, 1-5 kg P and 8-35 kg K and 1-3 kg S ha-1 (Dobermann et al. 1998) along with a few grams of each of the micronutrients. Thus taking grain yield of 6-8t ha-1 from the high yielding varieties or hybrids of rice can deplete soils heavily of their essential plant nutrient content and this has to be continuously replenished by chemical fertilizers, organic manures, green manuring and bio-fertilizers etc. Nitrogen- Of 14.3 million tones of N+P2O5+K2O consumed in 1996-97 in India, the share of N was 72%. This trend will be also continue in the future. There are two major reasons for this. Firstly, the crops remove large amounts of N and secondly N is easily lost from the soil (Prasad, 1996). In rice N use efficiency is 20-40% (Prasad and Power, 1997). Phosphorus- Phosphorus content in most Indian soils is within 200-800 ppm P (Khanna and Pathak, 1982); the range of organic P as % of total P is 10-30%. Therefore, most of P research in India and elsewhere is directed towards inorganic P, which makes up a major part of total P. Nevertheless contribution of organic P towards meeting crop requirement should not be overlooked where the rate of decomposition of soil organic matter is so fast. Sharply (1985) also pointed out that organically bound P is important in plant nutrition in tropical soils, particularly where little fertilizer is used. Potassium- Potassium in soils occurs in four forms, namely, mineral, non-exchangeable, exchangeable and solution K. These four forms, specially the latter 3 forms are in a dynamic equilibrium. The reversal of non-exchangeable to mineral K is a time taking process. Potassium bearing mineral is feldspars and micas, the weathering of which release K. Non- exchangeable K exists as fixed K in the interlayer spaces of 2:1 layer silicates, vermiculite, smectites, montmorillonite, bentonite, beidellite etc. and also in illite. Their weathering to 1:1 layer silicates or hydroxides of Al and Fe releases K. In addition, fixed K is also released to exchangeable or solution K due to wetting and drying cycles and several other factors.
  5. 5. Sulphur- The importance of S in Indian agriculture is next only to NPK. S deficiency has been noted in almost all states and in variety of crops. There are three main factors, responsible for S deficiency in Indian soils, namely, 1. Low organic matter content, 2. Heavy harvests and 3. Use of high analysis fertilizers containing no S such as urea and DAP. Micronutrients- So for as rice production in India is concerned, deficiencies of 3 micronutrients have been reported. First of all zinc deficiency in rice fields was noticed in tarai soils (Nene, 1966). Later deficiency of Fe was noticed on sandy soils of Punjab (Takkar and Nayyar, 1984). Of late B deficiency in rice has been reported on highly calcareous soils of Bihar (Sakal et al, 1988). Incidentally all these 3 micronutrients have poor mobility in plants (Prasad and Power, 1997). Integrated Plant Nutrient System (IPNS)- IPNS or INM (Integrated Nutrient Management) aims at reducing the amount of chemical fertilizer applied to fields and increasing its efficiency by adoption the best time, method and source of application and utilizing sources other than chemical fertilizers such as organic manures, green manures and biofertilizers to meet part of the nutrient need of the crops and cropping systems. The organic and other bio-sources of plant nutrients not only work as an addition to the nutrients supplied through chemical fertilizer but by positive interactions they also increase their uptake and efficiency and thereby reduce environmental hazards such as addition of ammonia, nitrogen and nitrous oxide to atmosphere or eutrofication of the surface and ground waters (Prasad, 1997). IONS is much more applicable to rice than they any other crop because of extensive work on biological nitrogen fixation in rice culture using blue green algae (BGA) (Venkataraman 1979), Azolla (Singh, 1997), green manuring (Palaniappan, 1997), and Farmyard manure (FYM)(Tandon, 1997). Water Management- Compared to other crops, rice production is less efficient in the way it uses water. Irrigated rice is a heavy consumer of water; about 5000 litres of water is required to produce 1 kg rice (IRRI, 1994-95). Most rice in India is grown during kharif season when the monsoon comes in torrents over a short period and the bulk of rain water received is lost as run off. In rainfed rice system, where most of the rice is grown in India, farmers have little control over their water supply. Water is either too much or too less, and continues to be the main constraint to production. Efficient water management is the key to successful rice production. Rice is a semi-aquatic plant and its water requirement of varies from 1190-2650 ha-mm depending upon soil, climate and varietal characteristics. Out of this, 15-20 ha-mm of water is needed for nursery land preparation, 25-40 ha-mm for raising seedlings, 200-300 ha-mm for land preparation and rest 950-1290 ha-mm for raising the crop in main field. Much of water applied to rice field is lost by percolation and surface run off. Percolation losses may vary from 1mm day-1 in heavy and shallow water table conditions to 10 mm day-1 in light soils. For reducing these losses, growing of rice in large blocks, leveling of land, proper pudding, compaction, embedding a polythene sheet at a 30 cm soil depth, application of bitumen, asphalt, adding heavy clay and 1-2 % bentonite with small quantities of sodium chloride and sodium carbonate are recommended. Continuous flooding at a static 2-5 cm depth has been recommended by many workers for potential yields. Shallow submergence during the critical stages of initial tillering and/ or flowering and maintenance of soil moisture at saturation to field capacity during the rest of the growth stages gave yields comparable to those obtained under continuous shallow submergence. The practice of intermittent submergence saves about 30 to 50 per cent water. Drainage is a important of rice, because continued stagnation of water often leads to accumulation of toxic substances and silt deposition. The drainage should be synchronized with the period just following tillering and flowering. The drainage period could last from 3-7 days depending upon the type of soil; heavier the soil longer the drainage period. Weed Management- Unlike other cereal crops, rice has to encounter great weed problem. A large number of weed species invade rice crop every year. About 1400 weed species of 466 genera belonging to 97 families have been found in different cultures in India (Moody 1989). However, their demography, dynamics, dominance and phytosociology vary with variation in climate, rice cultures and agronomic practices. Infestation of these weed species is a major constraint to increasing rice production. Weeds interfere with rice growth by competing for light, water and nutrients. Besides weeds secrete toxic root exudates or leaf leachates which depress growth of the rice plant and also are alternative host of many pest organisms which adversely affect rice production.
  6. 6. Method of Weed Control Manual: Handweeding is the most widely used method for controlling weeds in upland rice. Normally two weeddings are done. Time of weeding slightly varies in different regions but weedings are done within 15 to 45 days after sowing; these also coincide with critical period of crop weed competition. For example, Vaishya et al. (1992) in the studies at Faizabad and Tiwari and Ram (1991) ay Kanpur found that two early handweedings at two week intervals after sowing were better than one handweedings either 15,30 or 45 days after sowing. Mechanical: Only limited number of implements such as hand hoes and bullock drawn desi ploughs are used to control weeds in upland direct seeded rice. Chemical: Use of herbicides is gradually increasing in upland rice culture. Herbicides are expensive to small farmers but not to the large farmers who face the problem of labour shortage (Behra et al.1997). A large number of herbicides have been tested by agronomists and these are: Anilophos, Avirosan, Bentazan, Benthiocarb, Bifinox, Butachlor, Butralin, Chlorosulfuroan-methyl, Dichlofop methyl, Dinitramine, Dichlomate, Drepaman, 2,4-D, Fluchloralin, MCPA, MCPB, Molinate, Nitrofen, Pendimethalin, Pretilachlor, Piperphos, Propanil, Paraquat, Oxadiazan and Oxyflourfen. Insect Pests of Rice and Their Management- The environment of rice ecosystem is congenial for insect growth and development. There are over 800 insect species damaging rice in one way or another, although majority of them do very little damage (Dale, 1994). In India about the dozen insect species damage the rice crop seriously in different regions. The insect pests on an average inflict 20-25% crop loss in our country. If these losses are curtailed to some extent, the rice production can be enhanced substantially. The pesticides have played a significant role in controlling pest menace boosting food production. However, indiscriminate use has created a host of environment related problems. Therefore emphasis is now being laid on management of pests through integrated pest management (IPM), which is an ecologically sound way of tackling pest problems. Brown Plant Hopper (BPH) (Nilaparvata lugens Stal.)- Brown plant hopper has become a serious pest on high yielding cultivars of paddy in many states including Punjab, U.P., A.P., West Bengal. Haryana and Tamil Nadu. The nymphs of BPH are brown in color. The adult get attracted to light during night. In southern and eastern states the pest breed on paddy throughout the year, while in North India its activity is witnessed in kharif only. The eggs are laid by females on leaf sheaths. BPH is a long range migrant capable of migrating 200-300 km (Tu, 1979). Management- (iUse resistant cultivars like Manasarowar, Bhadre, Jyoti, CO42, IET 7575, IET 6315, MTU 5249 (Dhaliwal and Arora,1996). (ii)Avoid excess use of nitrogen. (iii)Set up light traps to monitor and control population. (iv)Ensure alternate wetting and drying of the fields. (v)On need spray carbaryl 50 WP 0.15% or monocrotophos 36WSC 0.04% or chlorpyriphos 20EC 0.05% or apply cabofuran 3G 20 kg ha-1 or phorate 10G 12.5 kg ha-1. White Backed Plant Hopper (WBPH) (Sogatella furcifera Hovarth)- white backed plant hopper is active throughout the year in southern states, where as in northern regions it starts its activity in May in nursery and attains peak in August-September. The nymph of WBPH is white or grey, while adults have a white stripe at their back. The eggs are laid on the leaf sheath. Management- (i)Use resistant cultivars like AR 133, IC25687, Tangner and Amellbero (Dhaliwal and Arora, 1996). (ii)On need apply Carbofuran 3G 20 kg ha-1 or phorate 10G 12.5 kg ha-1 or spray carbaryl 50WP 0.15% or monocrotophos 36WSC 0.04% or Chloropyriphos 20EC 0.05%. Direct the spray towards the base of the plants. Green Leaf Hopper (GLH) (Nephotellix nitropictus Stal.)- Green leafhoppers are found in all rice growing tracts but have assumed serious proportions in certain years in M.P., A.P., Orissa, Bihar and West Bengal. The leafhoppers are called so because they rest and feed mainly on the foliage in contrast to plant hoppers which are mainly found on the basis of plants. In northern states where only one crop of paddy is taken the leafhoppers appear in June-July and reach peak populations in September-October, while in eastern and southern parts these are active in both kharif and rabi crops. The nymph and adults of GLH are green in color. The adults have black
  7. 7. spot and black patch on wings. The female lay eggs in batches on the inner surface of leaf sheath. Several weeds serve as alternate hosts for the pest. Management- (i)Use resistant cultivars like IR20, IET7301, IET7302, IET7303 and Vani (Dhaliwal and Arora, 1996). (ii)Apply carbofuran 3G 20kg ha-1 or phorate 10G 12.5 kg ha-1 or spray carbaryl 50WP 0.15% or monocrotophos 36 WSC 0.04% or chloryriphos 20 EC 0.05%. Rice Mealy Bug (Ripersia oryzae Green)- The rice mealy bug is common in rainfed areas. Drought with moderately high temperature favours the infestation of the pest (Sheshgiri Rao and Kulshrestha, 1985). The mealy bugs are found incolonies between the stem and leaf sheath. Nymphs and adults are sedentary and suck sap from stems. The infested plants appear stunted and scorched. High incidence inhibits panicle emergence and plants may even dry. The infestation is localized in patches. Ants visit the mealy bug infested plants and are also found to carry the pest to uninfested plants. Heavy losses to rice due to mealy bugs have been reported from several parts of India (Mannen, 1976). Management- Spray endosulphan 35EC 0.07% or fenitrothion 50EC 0.1% or dimethoate 30EC 0.03% or malathion 50EC 0.01%. The spray should be directed towards the base of the plants. Paddy Aphid (Hysteroneura setariae Thoms) - The aphids are sporadic pests of paddy in humid areas. The wingless adults are rusty to dark brown in color and nymphs are pink. Both nymphs and adults suck sap from leaves and unripened grains and cause yellowing of leaves. Severe infestation reduces the vigour of plants and as a result chaffy earheads may be produced. Management- (i)Avoid excess use of nitrogen (ii)Spray endosulfan 35 EC 0.07% or fenitrothion 50 EC 0.1% or dimethoate 30EC 0.03% or monocrotophos 36WSC 0.04%. Rice Root Aphid (Tetraneura hirsuta Butler)- Rice root aphid is a major pest found only in well drained soil in rainfed environments. The females are globular and light red in colour, while nymphs are reddish brown. The root aphids are found in colonies below the soil surface and suck sap from roots. They sometimes feed on stems when population becomes very high or the roots are submerged. The attacked plants appear yellowish and leaf tips become curled up and dry. Management- For controlling this pest spray dimethoate 30EC 0.03% or monocrotophos 36WSC 0.04% or endosulfan 35EC 0.07% or fenthion 100EC 0.1%. Yellow Stem Borer (Tryporyza incertulas Walker)- The yellow stem borer is specific pest of rice. In northern regions of the country, the pest is active from April to October, while in southern states it multiplies throughout the year. Intensive cultivation of improved cultivars of rice has accentuated the stem borer problem. The female moth has yellowish forewings with a single dark spot at the centre, while the male has numerous small brown spots on them. The eggs are laid in batches of the leaf tips, covered with brown yellow hair. The full grown larva is pale yellow with orange yellow head. The population takes place in the infested tiller. Management- (i) Carry out deep ploughing of the fields in summer. (ii) Avoide excess use of nitrogen. (iii) Use light traps to attract and kill moths. (iv) Follow seedling root dip treatment in 0.05% chlorpyriphos emulsion for one minute before transplanting in endemic areas (Singh and Dhaliwal, 1994). This techniques does not harm natural enemies of the pest. (v) On need, apply carbofuran 3G 20 kg ha-1 or phorate 10G 12.5 kg ha-1 or spray malathion 50EC 0.1% or phosalone 35EC 0.1% or endosulphan 35 EC 0.05% or quinalphos 25EC 0.04% or fenitrothion 50EC 0.1%. Pink Stem Borer (Sesamia inferens Walker)- The pink stem borer is a polyphagous pest feeding on wheat and other cereals besides rice. It is distributed throughout India. The pest weeds actively from March to November on rice and then migrates to wheat. Therefore it is an important pest in rice-wheat cropping system. The moths are straw colored with stout body. The eggs are laid on leaves or on ground. The damage is caused by caterpillars which are pinkish brown with smooth cylindrical body. Management- (i) Avoid rotation of rice with other graminaceous crops.
  8. 8. (ii) Carry out deep ploughing of the fields in summer. (iii) Avoide excess use of nitrogen. (iv) Use light traps to attract and kill moths. (v) Follow seedling root dip treatment in 0.05% chlorpyriphos emulsion for one minute before transplanting in endemic areas (Singh and Dhaliwal, 1994). This techniques does not harm natural enemies of the pest. (vi) On need, apply carbofuran 3G 20 kg ha-1 or phorate 10G 12.5 kg ha-1 or spray malathion 50EC 0.1% or phosalone 35EC 0.1% or endosulphan 35 EC 0.05% or quinalphos 25EC 0.04% or fenitrothion 50EC 0.1%. Rice Leaf Folder (Cnaphalocrosis Medinalis Guenee)- The leaf folder is prevalent in almost all rice growing areas of the country. This pest attained importance only after the adoption of high yielding varieties. Several outbreaks of leaf folder have reported in India (Chatterjee, 1979). The moth is orange brown with many wavy lines and dark band on the margin of the wings. The female lays eggs on leaf blade. Moths are nocturnal and during day time they rest on under surface of leaves. The newly hatched larvae are greenish white in color. Management- On need spray carbaryl 50WP 0.25% or quinalphos 25EC 0.05% or monocrotophos 36WSC 0.04% or Choloropyriphos 20EC 0.05% or fenitrothion 50EC 0.06%. Apply the insecticide in such a way that entire foliage is covered with spray and larvae inside inside folds are affected. Climbing Cutworm (Mythimma separate Walker)- The climbing cut worm has become serious pest of paddy in several parts of India. Severe outbreaks of the pest have been reported from Manipur, Haryana, Orissa and Delhi (Chaudhary and Singh, 1980; Barwal, 1983; Chander and Sharma, 1997). The adult moth is stout and red brown in color. The eggs are laid in batches on leaf sheaths. Management- (i) Spray with water suspension of entomophilic nematode, Neoaplectana sp. (DD-136) in the clumps (Sheshagiri Rao and Kulshrestha, 1985). (ii) Spray with chlorpyriphos 20EC 0.05% or endosulfan 35EC 0.07% or quinalphos, 25EC 0.07% or apply malathion dust or carbaryl dust @ 25-35 kg ha-1. The spray should be directed towards the base of plants. Rice Swarming Caterpillar, (Spodoptera mauritia Boisdual)- The swarming caterpillar is a sporadic pest occasionally causing upto 20% loss in rice yield. Severe outbreaks of this pest have been reported from certain areas in India (Sathiyanandam et al, 1984). Adult is a stout, grayish brown moth with black spots on fore wings. The hind wings are whitish brown. The eggs are laid in batches on plants and covered with grayish hair. Newly emerged larvae are green. In South India, this pest is prevalent during October to December. Management- (i) Carry out deep ploughing of the fields in summer. (ii) Spray endosulfan 35EC 0.1% or chlorpyriphos 20EC 0.05% or quinalphos 25EC 0.075% or apply carbaryl or malathion dust @ 25-30 kg ha-1. Insecticide should be applied on to the base of the plant and soil crevice where larvae remain during day time (Chelliah and Bharathi 1994). The control measures are more effective if carried out on community level. Green horned caterpillar (Menantis Iada Ismene Cramer)- Green horned caterpillar or rice butterfly is a dark brown butterfly with large round spots on the upper surface of forewings. The caterpillars are yellowish green in colour and bear two red horns like projections on the head and hence called horn caterpillars. Due to green colour the caterpillars blend in the foliage and are not on leaves. The pupa is dark green and hangs from the leaf. Management- For managing this pest spray with chlopyriphos 20EC 0.05% or endosulfan 35EC 0.07% or quinalphos 25EC 0.075% or apply carbaryl dust or malathion dust @ 25-30 kg ha-1. Rice Caseworm (Nymphula depunctails Guenee)- The caseworm is a sporadic pest of paddy in most rice growing tracts of the country. This pest is common in low lying rice fields where water remains stagnant (Rao and Kulshrestha, 1985). Besides rice it also feeds on many grasses. In southern states the pest is active throughout the year while in North India it damages the crop from August to November. The adult is a small delicate moth having white wings with pale brown spots. Eggs are laid singly on leaves. The caterpillars are pale green with orange head. The caterpillars damaged the crop in nursery and field both.
  9. 9. Management- Spray with endosulfan 35EC 0.07% or monocrotophos 36WSC 0.04% or carbaryl 50Wp 0.25%. Rice Hispa (Dicladispa armigera Oliver)- The hispa is distributed throughout India and is very serious at certain places. The outbreak of hispa has been reported from many areas of the country (Budhraja et al. 1980; Chand and Tomar, 1984). Introduction of high yielding cultivars and associated agronomic practices have increased its, infestation. The adult is bluish black beetle with numerous short spines on the body. The grubs are legless and creamy white and remain concealed inside the deposit eggs there. The pest is active from May to October. Both adults and grubs damage the rice plants. Management- Clip the tips of seedlings prior to transplanting to remove eggs. Spray chlorpyriphos 20EC 0.05% or quinalphos 25EC 0.075% or monocrtophos 36WSC 0.04% or apply malathion dust or carbaryl dust @25-30kg ha-1. Rice Root Weevil (Echinocnemus oryzae Marshall)- The root weevil previously a minor pest, has become serious in some river basins in India (Dale, 1994). The adult weevil is black in colour and covered with chalky grey pubescence. The adult appears with first showers and covered of south westerly monsoon in southern states. The eggs are laid on basal portion of plants in cavities excavated by the females. On hatching, the grubs reach the root zone and damage the roots. Management- Deep ploughs the field in summer. Apply carbofuran 3G 20kg ha-1 or phorate 10G 12.5 kg ha-1. Paddy Gallmidge (Pachydiplosis orizae Wood-Mason)- The gall midge occurs in most of the paddy growing areas in southern and eastern parts of India. The extent and severity of gall midge infestation has significantly increased during last two decades (Dale, 1994). The adult is a small mosquito like fly with long legs. The female has bright red abdomen, while male is dark in colour. The eggs are laid on leaf blade or leaf sheath. Management- Collect and destroy ?silver shoots?, avoid excess use of nitrogen. On need apply carbofuran 3G 20kg ha-1 or phorate 10G 12.5 kg ha-1 or spray carbaryl 50Wp 0.15% or monocrotophos 36WSC 0.04% or endosulfan 35EC 0.07% or phosalone 35EC 0.1% or fenitrothion 50EC 0.1%. Rice Gundhi Bug (Leptocorisa varicornis Fab)- The gundhi bug or stink bug is a major pest of paddy in many states of India. The rice fields infested with this pest emit repugnant small and so this is called ?gundhi bug?. The bug is yellowish green and slender with long antennae and legs. The young nymphs are green but turn brown with development. The pest avoids hot sun and rests on the lower shady portions of the plant during the day. Both nymphs and adults suck juice from developing grains during milky stage and as a result some of the grains in the panicle remain empty. Management- Dust with carbaryl or malathion or endosulfan @ 25-30 kg ha-1 or spray endosulfan 35EC 0.07% or malathion 50EC 0.1% or fenitrothion 50EC 0.1% in the morning or late evening. Rice Panicle Thrips (Haplothrips ganglbaueri Schmutz)- The panicle thrips infest the inflorescence of various other cereal crops besides rice. The pest also multiplies in several weeds common in rice fields. The outbreak of panicle thrips have been reported from many parts of India. Incidence of this pest is serious in South India during first fortnight of December (Dale, 1994). Both nymph and adults damage the crop by desaping the emerging panicles, causing chaffy grains (Chaudhary and Ramzan, 1971). Management- For managing the panicle thrips spray malathion 50EC 0.1% or carbaryl 50WP 0.1% or endosufan 35EC 0.07% or monocrotophos 36WSC 0.04% or dust malathion or carbaryl @ 25-30 kg ha-1. Paddy Mites (Oligonychus oryzae Hirst)- The mites are common in humid coastal areas of Eastern, North Eastern and South India. The pest occurs in severe from during September- October. The nymphs and adults of mites suck sap from leaves and as a result characteristic whitish patches appear on the leaves. Later on the leaf turns to ash colour and dries from the tip downwards (Misra and Israel, 1968). The severe infestation results in yellowish of the leaves and the surface of the leaf blades appear sticky owing to delicate webs spun by the mites. Management- For managing the mites spray dicofol 18.5EC 0.1% or endosulfan 35EC 0.07% or fenitrothion 50EC 0.06%. Rice Diseases and Their Management
  10. 10. The production scenario is rapidly changing due to change in farming systems. The rice crop suffers from many disease caused by fungi, bacteria, virus, phytoplasma and nematodes. More than 70 diseases have been described by various workers from Indian subcontinent. Rice Blast- Blast caused by Pyricularia oryzae is considered the most serious rice disease because it rapidly and is highly destructive under favourable conditions. It may infect plants at any stage of growth. Leaf blasts stunts the plants and reduce the number of mature panicles, the weight of individual grains, and the weight and quality of rice. <B.MANAGEMENT-< b> (i) Treat seed with ceresin before sowing @ 2-2.5 g/kg. (ii) Spray with Zineb (or dithane Z-78, Dithane M-45) @ 2.5 kg/1000 litres of water. Brown Leaf Spot- Brown leaf spot caused by Helminthosporium oryzae has been found in all rice-growing countries in the Western Hemispere, Asia and Africa. Heavy damage has been reported from the disease through seeding blight. It has been reported that in India this disease contributed significantly to the Bengal famine in 1942, having caused to 50-90 percent yield loss. Management- Treat seed with ceresin @2-2.5 g/kg or 75% Thiram (0.25%). Grow resistant varieties. Sheath Blight- Sheath blight caused by Rhizoctonia solani was reported in Japan in 1910, it now occurs in most rice growing countries. The yield losses in the tropics are greater than in Japan. Sheath blight causes spot or lesion mostly on the leaf sheath. The lesions may extend to the leaf blade if conditions are favorable. The disease is especially destructive under highly humid and warm temperature. Management- Treat the seed with 75% Thiram @ 2.5g/kg seed. Soil application 25 kg/ha of Thiram or PCNB before transplanting. Grow tolerant varieties. Stem Rot- Stem rot caused by Helminthosporium sigmoideum var. irregular (Leptospheria salvinii or Magnaportha salvinii) was reported in India in 1913. The disease is present in all countries of Southeast Asia, in almost every field where rice has been grown for many years. The stem rot causes substantial losses in the crop. About 50% yield loss has been reported in Vietnam, 30-80% in the Philippines, 18-56% in India, and 10% in USA. Management- Burn rice stubble and infected straw. Grow resistant varieties. Avoid the continuous flooding of field. False Smut- False smut caused by Ustilaginoides virens was first described in ancient Chinese literature. Its presence was believed to indicate a good crop year. This belief is still common in countries of Southeast Asia. Most countries in Asia, Latin America and Africa reported the presence of the disease. The disease usually causes little damage, except in small areas under special conditions. Management- Spray or dust copper fungicides on the crop. Bacterial Blight- Bacterial blight caused by Xanthomonas oryzae cv. Orzal was first observed in Japan in 1884 and by 1960. In India, little attention was paid to it until 1963 when a severe outbreak occurred in Bihar. Bacterial blight occurs in all countries of tropical Asia. Yield losses in severely disease field range from 20-30%, and occasionally up to 50% in India, perhaps millions of hectares are infected and yield losses have been as high as 60 percent in some states. Management- Treat the seed by soaking it for hr in a mixed solution of streptocycline (0.015%) and wetable ceresin (0.05%), followed by hot water treatment at 52-540C for 30 minutes. Use seed from disease free crop. Tungro- Tungro was first recognized as a distinct virus in 1963 in the Philippines. Tungro is also commonly found in Malaysia, Indonesia, Thailand, Bangladesh and India particularly in West Bengal. Tungro is one of the most widely distributed and most destructive rice diseases in tropical Asia. During 1998, there was an epidemic of tungro virus in Punjab. Management- Spray a systemic insecticide like Furadan (carbofuron) @ 33 kg/ha or cypermethrin @ 500 ml/500 L of water to reduce insect vector population. Use resistant variety. Slurry treatment of seeds with Furadan 75% WP @ 1.3g/100 g of seed. Grassy Stunt- Graay stunt disease was first noticed in 1963 at the IRRI experimental farm and in farmer?s fields in the Philippines. Researchers established in 1964 that Nilaparvata lugens, commonly known as the rice brown plant hopper, transmits the disease. Grassy stunt also occurs in Ceylon, Thailand, India and Indonesia, Dr. E. Shikata of Hokkaido University found that siseased tissues contain mycoplasma-like bodies that may cause grassy stunt. The disease is
  11. 11. chrecterized by severe stunting, excessive tillering and an erect growth habit. The leaves are short, narrow, yellowish green, and covered with numerous rusty spots that form irregular blotches at late stages. Management- Oryza nivara, a wild rice has shown high resistance to grassy stunt. Grow resistant varieties. Rice Stem Nematode- The white tip nematode caused by Aphelechoides besseyi was first reported by Dastur in 1936 from the central province of India. It is now distributed in 28 countries of the rice growing areas of the world forming and important pest of rice in Bangladesh, Indonesia, Pakistan, Taiwan, Central Africa, Russia and USA. In India, it is prevalent in Assam, Kerala, Orissa, Tamil Nadu and Madhya Pradesh. Dispersal of the nematode occurs primarily through nematode infested grains, husk or plant remains and secondarily through irrigation water into which nematodes gets released from the primary sources. The nematode occurs both in upland and lowland fields, more severely in the latter. On an average 30-50% damage has been reported to be caused by this nematode. Management- Treat the seed by hot water at 550C for 10-15 minutes or 52-54oC for 30 minutes. Pre soaking of seed in water, 12h before hot water treatment, is quit effective in killing the nematode. Spray parathion @ 0.025% at 4.40 and 60 days after planting. Grow resistant varieties. Storage and Processing- Paddy is generally harvested at about 20-26 percent moisture content. It is dried to about 16-22 percent moisture before threshing. It is generally threshed manually by hand. Threshed paddy is further dried by spreading it in the sun. It dried during day and being hygroscopic, absorbs moisture during night. Thus it undergoes several cycles of drying and wetting, which caused fine crack called ?suncracks? in some grains, which break up during milling. Storage- Storage of paddy has to be in a good airtight container. It must keep the rice safe and also maintain its quality. It should provide protection against humidity, moisture, insects, rats, birds, microorganisms and other contaminants. Care should be taken to store different varieties of paddy separately to avoid their mixing up. Paddy should be clean and dry before storage. Impurities cause rapid deterioration in quality and quantity. High moisture content is the greatest enemy of good storage. High moisture paddy is easily attacked by insects and moulds. This causes hot spots to develop, which help mould and insect attack, leading to rapid deterioration. High temperature also promotes deterioration by moisture migration within the storage structures especially in soils. Hot paddy obtained after drying should not be immediately stored. It is estimated that 5 to 10 percent paddy is damaged in storage. Paddy dried to a safe moisture level (less than 14 percent wet basis) should be maintained dry and cool during storage. Paddy can be stored in bags construction, bags or bulk. The choice depends on a number of local factors including cost of construction, bags operating and handling equipment, transport system, labour and management. Either method can provide safe storage as long as scientific storage practices are observed. Storage containers may be made of steel or concrete but should be air tight. Milling- Rice is mostly consumed as cooked whole grain. Milling technology is therefore geared to obtain maximum outturn of milled rice and to reduce breakage to the minimum. Rice milling systems range from home-scale to large commercial scale. They include hand-pounding, hullers, disc shellers and rubber roll shellers.