Cultivation of Rice
Cereal: Any gramineous plant grown for its edible, nutrient rich, starchy seeds. The term refers primarily to Rice, Wheat, Maize, barley millet and oat. Cereals contain about 75% complex carbohydrates and about 10% protein plus fats and fibres World production of cereal crops exceeds 2 billion MT. Affluent nations use a large portion of the production as animal feed.
(1) Rice is the staple food of more than 60% of the world s population.
(2) Millions of people in Asia subsist almost entirely on rice and over 90% of the world s rice is both grown and eaten in Asia.
(3) In Bangladesh, rice is the most important and extensively grown food crop.
(1) Nothing was clearly known about the origin of Rice.
(2) However, rice is one of the oldest food crop and has been in cultivation in China, Bangladesh, Indonesia and Africa from a very ancient time.
(3) Vavilov, the Russian Scientist who postulated the origin of many of our cultivated plants and fruit trees considers the Indian sub-continent and Myanmar as the centre, where cultivated rice was first developed.
(4) That the Indo-Bangladesh sub-continent is the native home of rice is evident by the presence of a number of wild rice species as well as common rice.
(5) Dccandolle (1886) & Watt (1892) thought that south India was the place where cultivated rice was originated.
(6) However, rice was originated probably some where in the area extending from southern India to China.
Rice is originally a crop of the tropical and subtropical region but it is grown in the temperate region too. It is cultivated over a wide range of conditions within about 45• latitude north and 40• south of the equator. It is grown up to 10000 feet from sea level. This crop has a wider adaptability and grows from North Korea to South Australia and from sea level to an elevation of about 2600 m (Jumla,Nepal).
Rice is adapted to regions of high temperature and prolonged sunshine. The rice plants can grow flower and bear fertile grains in temperature ranging from 10-55•C.The optimum temperature however ranges from 27-35•C.(The average temperature required through out the life period ranges from 21-38•C.For germination 30-35•C is optimum. In seedling stage, if temperature is low, growth is restricted. Temperature requirement for the time of flower blooming is in the range 26.5-29.5•C.At the time of ripening temperature should be between (20-25•C)
There are varieties of rice which flower under exposure to certain day length only. These are photosensitive varieties of rice. Again there are varieties which are photo insensitive and flower when grown under both short and long day.
Optimum relative humidity ranges from 70-80%, but rice plants do not flower if humidity is either below 40% or above 95%.
Water is though considered to be the most important single factor in rice production yet rice yields are much higher in dry sunny season than in the rainy season. It can be cultivated as rainfed if, average annual rainfall is 200cm.
Rice can be grown from sandy loam to clay loam, almost all types of soil. But soil containing 40-60% clay is the best. Soils having good water retention capacity with good amount of clay and organic matter are ideal for rice cultivation. Soil Ph varies from 4.5 to7.5 but optimum Ph is5.5-6.5. Rice does not grow well in saline except a few varieties.
Characteristic of species and cultivars/Rice and wild species of Oryza
Rice belongs to the genus Oryza of Gramineae family. The genus Oryza includes 24 species of which 22 are wild and two are only cultivated namely Oryza sativa and Oryza glabrrima. All the varieties found in Asia, America and Europe belong to Oryza sativa and varieties found in West Africa belong to species Oryza glabrrima. The common wild rice Oryza sativa var fatua is polymorphic occurs as a weed in deep water rice field in Bangladesh. This wild rice closely resembles the cultivated rites in many respects. The fatua types cross easily with the cultivated rice giving fertile hybrids. It is considered that this wild rice is the intermediate progenitor of cultivated rice.
Oryza sativa is a diploid species having 24 chromosomes. The sativa rice varieties of the world are commonly grouped into three subspecies namely.
- 1. Indica: Rice grown in India belongs to the indica subspecies.
- 2. Japonica: The varieties developed in Japan belong to this subspecies. These varieties are adapted for cultivation in the sub-tropical and warm temperate regions.
- 3. Javanica: These are found mainly in Indonesia.
CLASSIFICATION OF RICE
(A) According to growing season
1. Aus rice: The world aus has been derived from the Sansicrit ashu meaning quick or early. The season designates the cultivation of the rice varieties which are planted in mid March-April and harvested in mid June- July. Their life duration is 80-120 days.
Aus rice are 2 types-
(a) Broadcast aus rice: seeds are directly sown in the prepared field in March to April. It is rainfed.
(b) Transplant aus rice: seedlings are raised in a dry nursery bed and then transplanted to main field in wet condition in May.
Local: Hashikalmi, Dular, Panbira, Kataktara, Kurmari, Surjamukhi, Morichbeti, Shaita.
HYV: Nizami(BR20), Niamot(BR21), Rahmat(BR24), Shraboni(BR26).
2. Aman: The word aman has been derived from Arabic meaming safety which indicates stability of the crop. The season designates the cultivation of the rice varieties which are planted in mid July and harvested in mid November- December.
(a) Direct seeded or broadcast /Floating/Deep water rice: seeds are directly sown in the prepared field in March to April & harvested in Nov- December.
(b) Transplanted aman: Seedling are raised in a dry nursery or wet nursery bed in June- July & transplanted in the main field in July-August & harvested in Nov- December.
Local: Latishail, Nizershail, Jhingashail, Pajam, Rajashail, Baisbish, Godalak, Gabura, Dola, aman.
HYV: Brrishail, Binashail, Dulabhog(br5), Kiron (BR22), Dishari(BR23).
3. Boro rice: Boro rice refers to the crop grown in submerged land lower in elevation. The season designates the cultivation of the rice varieties which are planted in November-December and harvested in March-April.
Local: Teiboro, Khaiyaboro, Pashushail, Banjira, Habigong-boro.
HYV:BR17(Hashi), BR18(Shahjalal), BR19(Mongal), BRRI dhan28, BRRI dhan29.
(B) According to photoperiod sensitivity: on the basis of photoperiod sensitivity all rice varieties can be grouped into two classes
1.Photosensitive/timely fixed variety/date fixed/ season bound/ short day variety: This type of rice gives flower depending on the differences of day length. A particular time of the year is needed for setting flowers e.g. T. aman rice.This class of rice plant flowers in the month of October and November due to influences of short day. This class of paddy will not flower if grown during any time from February onward till the day length is shortened in October and November. The vegetative growth of this type of rice takes place at long day length and flowering occurs during short day length. This type of rice is also khown as timely fixed/date fixed/season bound rice. They produce flower when day length below the critical day length. They are also called timely fixed varieties. Most of the indigenous aman rice vaeieties are photosensitive.
2. Photo insensitive/ day neutral: Photo insensitive varieties do not respond to differences in photoperiod, their length of life being independent of day so that they can be grown at any season. For this class of rice a particular period of the year is fixed for setting flowers i.e. if this rice is sown at any time of the year, it will flower after passing a specific period. E.g. Aus rice and boro rice. This is also known as periodically fixed rice. Most of rice varietes are photo insensitive.
(C) According to size of grain
1.Very fine rice: Kalizira, Dolabhog
2. Fine rice: Maximum aman rice (indigenous)
3. Coarse rice: Aus & Boro rice.
(D) According to colour of grain
1. Golden colour –Most of the rice varieties
2. Red colour – Harinmuda, Marichbati, etc.
3. Black colour – Kalizira, Hashikalmi.
This type of rice is actually floating rice and is grown in Jessore and Khulna as a mixed crop with tall boro under transplanted condition. They are extremely photosensitive and that,s why can be grown as mixed crop. Boro crop is harvested in dry fields in April and May and the stemmed Rayada paddy continues to grow with the rise of water and harvested in December.
Variety: Variety is a group of individual within a species, which are homogenous in all aspects. There are two varieties for rice local variety &High yielding variety (HYV).
Comparison between HYV & Local variety
|1.Short stature as a result plant does not lodge.||1.Long stature,as a result plant lodge|
|2.Plant is hard .||2.Plant is week.|
|3.Dark green in colour.||3.Light green in colour.|
|4.Leaves are broad, think,short and erect,leaves remain straight& vertical.||4.Leaves are long thin,and recumbent, leaves remain horizontal.|
|5.Leaves remain green even at time of harvesting.||5.Leaves become straw colour at the time of harvesting.|
|6.Photosynthesis rate is high.||6.Photosynthesis rate is low|
|7.High tillering ability.||7.Low tillering ability.|
|8.Takes more fertilizer and gives more yield.||8.Takes more fertilizer but gives low yield|
|9.Outbreak of diseases is high .||9.outbreak of diseases is low|
|10.Number of grains per panicle is higher.||10.Number of grains per panicle is lower|
|11.Grain straw ratio is 1:1.25.||11.Grain straw ratio is 1:2 or more|
|12.Less tasteful to eat.||12.More tasteful to eat|
Name and growing seasons of HYV rice varieties
Now a days (Around 65—-) HYV rice are beaing coultivated in Bangladesh of which 51 including 2 hybrid varieties are relesed from Bangladesh rice research Instiute. 3 from IRRI, I from China,3 from BAU, 7 from BINA. They are listed below along with their growing seasons:
|Varieties||Growing seasons||Varieties||Growing seasons|
|1.Chandina(BR1)||AUS BORO||BRRI dhan40||AMAN|
|2.Maka (BR2)||Aus Boro||BRRI dhan41||AMAN|
|3.Biplob (0BR3||Aus Aman Boro||BRRI DHAN42||AUS|
|5Dulabhogue (BR5)||Aman||BRRI DHAN44||AMAN|
|6.BR6||Aus Boro||BRRI DHAN45||BORO|
|7.BRRI-balam(BR7)||Aus Boro||BRRI DHAN46||AMAN|
|8.ASHA(BR8)||Aus Boro||BRRI DHAN47||BORO|
|9.Sufala(BR9)||Aus Boro||BRRI DHAN48||AUS|
|13.Gazi (BR14)||Aus Boro|
|14.Mohini(BR15)||Aus Boro||BRRI HYBRID1||BORO|
|15.Shahibalam||Aus Boro||BRRI HYBRID2||BORO|
|27.BRRI dhan28||Boro||BAU 125|
|31.BRRI dhan32||Aman||IRATOM24||AUS BORO|
|32.BRRI dhan33||Aman||IRATOM-28||AUS BORO|
BRRI hybrid dhan 1 for boro season (initially recommended by Government in Jessore and Barisal district) yield 7.5-5.5 t/ha which is one ton more than traditional HYV.
|RICE||Seeding time||Transplanting time||Harvesting time|
|B.Aus||March –April||July -August|
|T.Aus||April - May||July-August|
|B.Aman||March – April||Nov- December|
|T.Aman||June - July||July - August||Nov – December|
|Boro rice||Oct - Nov||Decem-January||April- May|
Production practices of transplant rice
Land preparation and seedling raising in nursery bed Transplanting of seedling: At first, sprouted seeds are sown in the nursery bed for raising seeding. When the age of seedlings becomes 40-45 days (boro rice) 20-35 days (aman rice)& 20-30 days (aus rice) then they are transplanted in the main field. There are several types of nursery bed. These are day nursery bed, wet nursery bed, floating nursery bed, dapog nursery bed.
For dry nursery bed, the should be several ploughing and cross ploughings along with laddering to break the clods and level the soil. On the other hand in case of wet nursery bed after supplying of water the land should be puddle by several ploughings and cross ploughings along with laddering to level the soil.
In dry nursery bed dry seeds sre to be sown whereas in wet nursery bed sprouted seeds are to be sown.
500m2 nursery bed is required for transplanting in one hectare of land.
Dapog nursery bed: when there is no kind is available for making dry or wet nursery bed due to flood or other unfavourable circumstance, dapog method of raising rice seeding is practiced. For preparing a dapog nursery bed concrete floor , plastic sheet banana and plastered by mud to retain water and protect seeds from spreading out. Pre germination seeds are sown over the well arranged banana leaves plastic sheets or concrete floors. Usually 3-4 kg seed/m2 is used which is a very high seed rate compared to 100-150g of seeds being used for dry or wet nursery bed. After sowing seeds of dapog nursery bed water should be sprinkled at least a day to protect seeds /seedling against drying out.
Floating nursery bed
Floating nursery bed is specially suitable under flood affected condition. In a flood affected area there may be low land available for raising rice seedling and then it is adviserable to use this method. Here a floating platform is prepared over standing water by using bamboo matting or a floating rapt made of banana trunks. The bamboo matting or banana rapt is fixed with poles and two –three cm thick layer of mud is placed over the platform. Pre- germinated seeds are then used on the mud placed on rapt . The seed rate is similar to wet nursery bed.
Seed rate: In case of transplanted rice seed rate is 25-40 kg/ha. In case of broadcast rice seed rate is 60-100 kg/ha.
Seed selection: Healthy seeds should be selected.
1. Grading 2.Dipped in water solution (40 liter+2kgUrea)
Seed treatment: Seed should be treated with Agrosan GN1.5kg seed or Gransoan m 1g seed.
Care of nursery bed:After sowing seeds in the nursery bed care should be taken to raise healthy and strong seedling. In case of wet nursery bed water should be kept in all times.
Irrigation:Irrigation is to be given as and when necessary.
Drainage:Excess water should be drained out from the nursery bed.
Weeding: weeding is to be done if necessary.
Fertilizer application: If the land of seed bed is fertile fertilizer application is not necessary. But in case of unfertile and slighty fertile soil the flowing does of manures and fertilizers may be applied
Cowdung: 1-1.5 tons/500m2
Urea: 3-4 kg/500m2
Land preparation: After giving required amount of water the land should be puddled well by 3-5 ploughings and cross ploughings along with laddering depending on the soil type. The land shuld be leveled properly by laddering and spading. Weeds & stubbles should be removed from the land.
Fertilizer dose (kg ha -1)
For local variety
Urea 90 kg /ha TSP 75KG/HA NOP60kg /ha Gypsum 60kg/ha &ZnSOO4 10kg/ha. For HYV rice
Method of application:TSP, MOP, GYPSUM, &ZNSO4 all these fertilizers should be applied during final land preparation. Nitrogen should be applied in three equal splits/ instalments. The frist 1/3 should be applied at 20dat as top dressing the2nd 1/3ed should be applied during early tilering stage (30-35DAT) and last one third at panicle initiation stage (50-55DAT) AS TOP dressing.
Reasons for split application
Urea becomes available to plants within three days after application and remains available about one week.
Urea is lost through leaching, volatilization.
Uprooting of seedling and transplanting
The seedling should be uprooted from the nursery bed wgen they are suitable for transplanting the nursery bed should be moistened by the application of water so that root system is not damaged. Then the seedling are to be transplanted in the main filed.
Age of seedling:The age of seedlings varies from variety to variety . The general trend indicated that for shrot duration varieties 3-4 weeks and for long dueation varieties 5-6 weeks old seedlings are the optimum age for planting . Gererally the age of seedling should be 1 month to 45 days.
The age of seedlings are recommended from BRRI-
Age of seedlings for Boro =45 days
Age of seedlings for T.AUS =25 DAYS
Age of seedlings for Taman=30 days
Age of seedlings late T. aman=45 days
Line to line=25cm
Plant to plant=10-15cm
Seedlings per hill=2-3
Transplantation:Rice is transplantation maintaining line to line distance 25cm and hill to hill distance 15cm. Two/therr seedlings are transplanted per hill.
Weeding:The land should be kept free from weeds up to 30-40 days for AUS Aman seasons and 40-5- days roe Boro season. Two times weeding should he done. The first weeding is to be done after 25 days of transplanting and 2nd weeding after 45-50 days of transplanting .weeding may be done by different ways such as by uprooting by using Japanese rice weeder etc.
Water management in rice
Water is very important for rice . After transplantation water should be kept in the field in such a level that the seedings are not submerged or the field is not entirely dried. It is not needed to keep water always in rice field.
1.About 7-10 cm water needs to maintain from transplanting to maximum tillering stage. The level of water more than this impairs the production of tillers.
2. After 40 DAT water level should be increased to 12-15cm to stop late tiller prpduction.
3.Enough water needs to be maintained up to milk dough stage. From hard dough stage, drainage is necessary otherwise ripening will be delayed.
4. During application of fertilizer, water needs to be removed from the field and after 2-3 days the field should be irrigated again to increase the effectiveness of fertilizer.
5.Alternate irrigation and drying are the best.
6.Through sufficient rainfall is occurred in the country , uneven distribution of rainfall, irrigation and drainage are essential at growth stages of rice.
Insect: Rice stem borer rice ear cutting capterpillar rice hispa rice green leaf hopper Brown plant hoper rice case worm etc are the common insects for rice plant.
Contorl: They can be controlled by spraying different insecticides such as Diazinen 60ec 1LITER/HA malathion 57ec 1 liter/ha .
Diseases: Rice blast brown spot bakanae stem rot false smut tungro etc may occur.
Control: Hinosan (fungicide) 800ml/ha is used for rice blast brown spot bakanac & false smut diseases.
Harvesting: The crop should be harvested as soon as it matures If delayed grain may be lost due to damage by rats insects shattering and lodging. Timely harvesting ensures good grain quality consumer acceptance.since the grain is less likely to break when milled. The right stage for harvesting is when about 80% panicles have about 80%ripened spikelets. At the time of harvest the upper portion of the spikelets should be straw coloured the grain will contain about 20% of moisture .
At this time the should be cut itch serrate edged sickles by hand .The plants should be cut quite close to the ground and left in the field for a few days to dry. Later on they should be collected in bundles and stacked for threshing.
Threshing, drying, cleaning and storing
After harvesting we should not delay in . A neat and clean place is to be selected for threshing .The grains can be sppareated from the rice plant by beating but is not suitable.It is suitable to spparate the grains with the help of pedal thresher. Then the grains are to be dried in the sun at least 4-5 times. Then grainas should be cleaned with the help of winnower or air . After that the clean and dry grains are to be stored in gunny bags or by any other means. The moisture content of the grain should be 10-12% during storing .
1.Green colour of the grains becomes golden colour but some varieties attain their characteristics colour,
2. 20-25 days after panicle emergence rice matures.
3.The grains become hard if it is pressed by finger.
4. The moisture content of the grains should be around 20-25%.
Local: 2.5-3.0 t/ha.
HYV: 3.5-6.0 t/ha.
BR3 (Biplob) is the only HYV rice that can be grown in all the three season.
Variation of yield in three seasons of the same variety
If a rice is grown in three seasons with same care and management the yield will not equal in three seasons .The yield will be low,medium and high in Aus,Amon and Boro seasons respectively.It varies to the following seasons-
1. In Aus seasons
i. Generally outbreak of drought is high during sowing and production of the crop.
ii. Disease and insects infestations are high due to high temperature and high humidity.
iii. Prevails high temperature & humidity, as a result diseases & insect infestation is high.
iv. Photosynthesis rate is low because the sky often remains overcast or sky remains cloudy almost all the season. That is why less photosynthesis occurs & accumulates less amount of food.
v. Respiration is greater than photosynthesis. As a result food materials are most by respiration or a large amount of food produced by photosynthesis is spent through respiration due to the prevailing high temperature.
vi. The crops are often damaged at seedling stage due to hail storm.
vii. The crops might submerge under water before harvesting.
viii. Life span is comparatively low or life cycle is short.
2. In aman season
i. Comparatively the sky remains less overcast as a result photosynthesis also occurs more than aus season.
ii. Disease and insect infestation are lower than aus season.
iii. Photosynthesis is higher than respiration due to comparatively low temperature & clear sunshine. As a result high amount of food material is accumulated.
iv. Life cycle is greater than aus season.
3. In boro season
i. Loss of prepared food through respiration is less due to low temperature.
ii. Disease and insect infestation are less due to low temperature & humidity.
iii. Light hour is high and hence photosynthesis rate is high.
iv. Weed infestation is comparatively low.
v. Plant does not lodge.
vi. Life span is high.
Photoperiodic Introction: There are some short day varieties of rice that if they gain attain short day in time of their life cycle this effect prevails and produce flower in long day condition . This process is called photoperiodic induction. As for example if Kalizira rice is transplanted in December –Januray the short day induction is remain and produce flower in Aoril and the rice harvested in June ie flower is production in long day condition. This occurs due to photoperiodie induction.
Microclimate is the local climate that generates the surface of the land and usually prevails within the limit of the plant canopy eg climate of rice field microclimate.
Microclimate is the local climate within the limit of plant canopy can be altered has no influence on the selectivity of the crop
Macroclimate is the regional climate extended over the wider areas and out of the limit of the plant canopy e.g climate of a country is macroclimate. Macroclimate is regional climate beyond the limit of the plant canopy can not be altered regulate the selectivity of the crop.
Growth phases and stage of rice plant
The life cycle of rice plant may be divided in to three phases:
- Vegetative phase
- Reproductive phase
- Ripening phase
These phases may be subsequently divided into different growth stages.
This phase begins with the seed germination which is signified by the emergence of radicle or coleoptile in the germinating embryo during the vegetative phase the plant undergoes the following stages:
1.Seedling stage: This stage follows seed germination and the seedling develop germinal and lateral roots . Seedling stage is generally considered from germination until the plants develop the fifth, During this stage the seedling absorbs the food from the endosperm.
2.Transplanting stage: Only the transplanted rice plants undergo this stage. It covers the period from uprooting of the seedling to full recovery .Direct seeded rice plants do not undergo through this stage.
3. Tillering stage: This stage starts with the appearance of the first tiller from the auxiliary bud in one of the lowere most nodes. The number of tillers increases at a point more rapidly until the maximum number is reached. Then some tillers die the number tillers declines and levels off. The plant stops tillering after the tertiary tillers have been produced.
During the reproductive phase the plant undergoes the following stages:
- Panicle initiation stage: The reproductive phase begins before reaching the stage of producing maximum number of tillers at about the time of the highet tillering activity or thereafter. This phase is marked by the initiation of the panicle production of microscopic dimension on the growing shoot.
- Booting and internode elongation stage: As the young panicle develops it become s visible to the naked eye in a few days . This marks the beginning of the booting stage . The tiny panicle is transparent structure measuring 1or 2 mm long with a fuzzy or spongy tip. As panicle development continues the spikelets be come distirigushable.The increase in the size of the young panicle and its upward extension inside the flag leafcauses the sheath to bulge. The time of occurrence of internode elongation stage differs among varieties With late maturing varieties the accelerated elongation of the upper internodes may begin after panicle initiation.
- Heading stage: This stage is marked by the emergence of panicle tip out of the flag leaf sheath . Emergence continues until 90% of the panicles are out of the sheaths.
- Flowering stage: Flowering or blooming or antheis begins with the protrusion of the first dehiscing anthers in the terminal spikelets on the panicle branches. Flowering continues successively until all spikelets in the panicle bloom . Pollination and fertilization then follow.
The rice grain develops after pollination and fertilization. Grain development is a continuous process and the grain undergoes distinct changes before it fully maters.
- I. Milk stage: The contents of the caryopsis or first watery but later turn milky in consistency.
- II. Dough stage: The caryopsis turns into soft dough and subsequently into hard dough.
- III. Maturity stage: The individual grain is nature when the caryopsis is fully developed in size and is hard clear and free from greenish tint. This stage is completed when more than 90% of the grains are fully ripened.
Component phases of the vegetable phase
The vegetable phase is the most variable of all growth phases of the rice plant. This phase is markedly affected by the prevailing day length and temperature and can be subdivided into the following two component phase;
- Basic vegetative phase (BPV) The basic or active vegetable phase is the minimum period of vegetative growth required by the rice plant before it will initiate panicle primordium. The usual variations of day length have little or no effect on its duration. However in certain varieties temperature may either shorten or lengthen its duration.
- Photo-period sensitive phase (PSP) the photo- period sensitive or lag vegetative phase is the portion of the vegetative phase in which the flowering date is determined by the day length to which the plant is exposed. It is therefore from the end of the basic vegetative phase to panicle initiation, Only the photo- period sensitive varieties have this component phase.
|Stage||Date of occurrence from seeding||Date of occurrence before maturity|
|Panicle initiation||About 60-70 days after seeding for 130 days non seasonal varieties and variable in seasonal varieties.||70-75 days from date of maturity regardless of variety.|
|Booting||About 75-days after seeding for 130 days non seasonal varieties and variable in seasonal varieties.||About 55 days from date of maturity regardless of variety.|
|Flowering||About 100 days after seeding for 130 days non-seasonal varieties and variable in seasonal varieties.||25 days from date of maturity regardless of variety.
Approximate duration of the growth phase
Basic vegetative phase 25-65 days for most varieties.
Lag vegetative phase varies grealth according to day leagth in seasonal varieties.
Reproductive phase About 35 days regardless of varieties
Ripening phase 25-35 days regardless of varieties
Growth duration of major crops grown in the country
|Name of the crops||Seeding/Transplanting||Harvesting|
|Broadcast Aman rice||February||December|
|Transplant Aman rice||July||December|