Dr. Sudhir K.

Rajpoot,IAS,BHU

Rice (Oryza sativa L.)

Introduction: Rice is the staple food crop of more than 60 per cent of the world’s
population. It is the staple food of most of the people of south-eastern Asia. About
90 per cent of all rice grown in the world is produced and consumed in the Asian
region. In India, rice is the most important and extensively grown food crop,
occupying about 45 to 46 million hectares of land.

Rice occupies a pivotal place in Indian agriculture and is the staple food for
more than 70 per cent of population and a source of livelihood for about 120-150
million rural households. It accounts for about 43 per cent of total foodgrain
production and 55 per cent of cereals production in the country.

Rice is primarily a high-energy or high calorie food. It contains less protein

than wheat. The protein content of milled rice is usually to 7 percent rice, however,
compares favourably with other cereals in amino acids content. The biological
value of its protein is high. The fat content of rice is low (2.0 to 2.5 per cent) and
much of the fat is lost during milling. Rice grain contains as much B group
vitamins as wheat. Milled rice loses valuable proteins, vitamins and minerals in the
milling process during which the embryo and the aleurone layer are removed.
Much of the loss of nutrients can be avoided through parboiling process.

The by-products of rice milling are used for a variety of purposes. Rice bran
is used as cattle and poultry feed. Rice hulls can be used in manufacture of
insulation materials, cement, cardboard and as a litter in poultry keeping. Rice
straw can be used as cattle feed as well as litter during winter.

AREA AND DISTRIBUTION

Rice is the world’s leading food crop. Cultivated over an area of about 165
millon hectares with a production of about 700 millontonnes (paddy), In terms
of area and production it is second to wheat. It provides about 22 per cent of the
world’s supply of calories and 17 per cent of the proteins. Maximum area under
rice is in Asia. Among the rice growing countries, India has the largest area
(45million hectares) followed by China and indonesia. In respect of production,
India ranks second with 131 million tonnes of paddy next to China (200 million
tonnes of paddy). In regard to average yield per hectares, Egypt ranks first
followed by USA. Average rice yield of India is only 2929 kg per hectare.

In India rice is grown ion almost all the states. Andhra Pradesh, Bihar, Uttar
Pradesh, Madhya Pradesh and West Bengal lead in the area. West Bengal and Uttar
Pradesh have the highest rice production. The average yield per hectare is highest
in Panjab (3346 kg/ ha) .

Rice export from India

India is one of the biggest exporters of rice in the world.

Basmati rice
India is the leading exporter of the Basmati Rice to the global market. India
exported around 4.4 million metric tons of Basmati rice worth Rs. 38524.11
Crores during the year 2022-23. India annually exports more than 4 million
tons of basmati - a premium long-grain variety famed for its aroma - to Iran, Iraq,
Yemen, Saudi Arabia, the United Arab Emirates and the United States, among
others. Europe is another big market for the rice.

Areas of Cultivation:The Indian states with the highest areas of Basmati rice
under production are Jammu and Kashmir, Himachal Pradesh, Punjab, Haryana,
Delhi, Uttarakhand and Western Uttar Pradesh.

Non-Basmati rice

According to APEDA, "any rice other than Basmati Rice is named as Non-
Basmati rice."India exported 7.5 million metric tons of Non-Basmati rice worth
US$3 billion.The main export destinations were Nepal, Benin, Senegal,
Bangladesh and Guinea
 CLASSIFICATION

Rice belongs to genus Oryza of Gramineae family. The genus Oryza includes 24
species, of which 22 are wild and two namely Oryza sativa and Oryza glaberrima
are cultivated. All the varieties found in Asia, America and Europe belong to O.
sativa and varieties found in West Africa belong to species O. glaberrima.

Oryza sativa is a diploid species having 24 chromosomes. The sativa rice

varieties of the world are commonly grouped into three subspecies namely
india, japonica and javanica.

Indica:Rice grown in India belongs to the indica subspecies. They are

characterised by having leaves slightly pubesecent and pale green in colourIndicas
are awnless or possess short and smooth awns. The fruits is caryopsis, elongated,
thin, narrow and slightly flattened.

Japonica: The varieties developed in Japan belong to this subspecies. These

varieties are adapted for cultivation in the subtropical and warm temperate
regions. Japonica varieties mostly have oval and round grains. They may be
awned or awnless, Leaves are narrow and dark green in colour.

Javanica: They are characterized by a stiff straw, long panicle with awned grains,
sparse tillering habit, long panicle with awned grains, sparse tillering habit, long
duration and low sensitive to difference in day length. These are found mainly in
Indonesia.

CLIMATIC REQUIREMENTS

In India rice is grown under widely varying conditions of altitude and climate. Rice
cultivation in India extends from 8 to 35°N latitude and from sea level to as high
as 3000 metres. Rice crop needs a hot and humid climate. It is best suited to
regions which have high humidity, prolonged sunshine and an assured supply of
water. The average temperature required throughout the life period of the crop
ranges from 21 to 37°C. At the time of tillering the crop requires the higher
temperature than for growth. Temperature requirement for blooming is in the
range of 26.5 to 29.5°C. At the time of ripening the temperature should be
between 20-25°C. Photo periodically, rice is a short-day plant. However, there
are varieties which are non-sensitive to photoperiodic conditions.

SEASON

Rice-growing seasons vary in different parts of India, depending upon

temperature, rainfall and other climatic conditions. In parts of eastern region and
Peninsular India, the mean temperatures throughout the year are favourable for
rice cultivation and hence two or three crops of rice are taken in a year. In
northern and western parts of the country where winter temperature are fairly
low only one crop of rice is taken during Kharif season. There are three seasons
for growing rice in India as given below.

Crop Local Name Sowing Harvest

Season Time Time

Kharif Aus (West Bengal, Bihar) May-June Sept-Oct.

Rabi Aman or Aghani June- July Nov.-Dec.

Summer or Dalua (Orissa) Nov.-Dec. March-April

Spring Boro (West Bengal)

SOIL

In India rice is grown under so diverse soil conditions that it can be said that there
is hardly any type of soil in which it cannot be grown, including alkaline and
acidic soils, Soils having good water retention capacity with good amount of clay
and organic matter are ideal for rice cultivation. Clay or Clay loams are most
suited for rice cultivation. Such soils are capable of holding water for long and
sustain crop. Rice being a semi-aquatic crop, grows best under submerged
conditions. A major part of rice crop in India is grown under ‘low land’ conditions.
Rice plant is able to tolerate a wide range of soil reaction, but it does have a
preference for acidic soils. It grows well in soils having a pH range between 5.5
and 6.5. It can be grown on alkali soils also after treating them with gypsum or
pyrite.

Important growing ecology of rice: Rice farming is practiced in several agro

ecological zones in India. No other country in the world has such diversity in rice
ecosystems than India. Because cultivation is so widespread, development of four
distinct types of ecosystems has occurred in India, such as:

Irrigated Rice Ecosystem

Rainfed Upland Rice Ecosystem

Rainfed Lowland Rice Ecosystem

Flood Prone Rice Ecosystem

Irrigated Rice Ecosystem: Irrigated ecosystems are the primary type found in
East Asia. Irrigated ecosystems provide 75per cent of global rice production. In
India, the total area under irrigated rice is about 22.00 million hectares, which
accounts about 49.5per cent of the total area under rice crop in the country. Rice is
grown under irrigated conditions in the states of Punjab, Haryana, Uttar Pradesh,
Jammu & Kashmir, Andhra Pradesh, Tamil Nadu, Sikkim, Karnataka, Himachal
Pradesh and Gujarat.Irrigated rice is grown in bunded (embanked), paddy fields.
Rainfed Upland Rice Ecosystem: Upland zones are found in Asia, Africa, and
Latin America. In India, the total area under upland rain fed rice in the country is
about 6.00 million hectares, which accounts13.5per cent of the total area under rice
crop in the country. Upland rice areas lies in eastern zone comprising of Assam,
Bihar, Eastern M.P., Orissa, Eastern U.P., West Bengal and North-Eastern Hill
region. Upland rice fields are generally dry, unbunded, and directly seeded. Land
utilized in upland rice production can be low lying, drought-prone, rolling, or steep
sloping.

Rainfed Lowland Rice Ecosystem: Rainfed low-land rice is grown in such areas
as East India, Bangladesh, Indonesia, Philippines, and Thailand, and is 25per cent
of total rice area used worldwide. In India, low land rice area is about 14.4 million
hectares, which accounts 32.4 per cent of the total area under rice crop in the
country. Production is variable because of the lack of technology used in rice
production. Rainfed lowland farmers are typically challenged by poor soil quality,
drought/flood conditions, and erratic yields

Flood Prone Rice Ecosystem: Flood-prone ecosystems are prevalent in South and
Southeast Asia, and are characterized by periods of extreme flooding and drought.
Yields are low and variable. Flooding occurs during the wet season from June to
November, and rice varieties are chosen for their level of tolerance to submersion.

Methods of Nursery Raising

There are three major methods of raising nursery - viz.

i. The dry nursery where the dry seed is sown in dry soil. This method is
practiced in areas where water is not sufficient to grow seedlings in wet nursery

ii. Wet nursery where sprouted seed is sown on the moist puddled soil. Wet
nurseries are preferred under irrigated condition

iii. And the "dapog" method. This method of raising nursery has been
introduced in India from Philippines.

"Dapog" method is commonly prevalent in Philippines. The essential feature of

this method is to have a very thick stand of the nursery seedlings without any
contact with the soil. Generally, seedlings become ready for transplanting in 12
to 14 days.

Transplanting

Before transplanting, field should be puddled properly with bullock

or tractor drawn puddlers. Puddling is a very important operation in
transplanted rice. Puddling helps to kill the weeds and buries them
in puddled soils. It also suppresses the germination of weeds in
subsequent growing period of crop. Puddling keeps the soil surface
in a more even condition, besides creating beneficial physical,
biological and chemical conditions for rice plant growth.
Transplanting should be done with proper age of seedlings. In case
of short duration varieties, the seedlings should be uprooted from
 the nursery beds for transplanting , when it is three to four weeks
old. In case of medium and long duration varieties, four to five
weeks old seedlings should be transplanted.
Alwayshealthyseedlingsshouldbeusedfortransplantingatthefourtofive
leafstageorwhentheyare about 15-20 cms. high. As far as possible,
delayed transplanting should be avoided because it leads topoor
tillerings, early flowering of the main tillers and resulting in
reduction in yield. In alkaline soils aged seedlings of 45 days old
should be transplanted because old seedlings establish better than
youngseedlings of 25 days age or so.

Manure and Fertilizer management in paddy: Organic manures are as much as

important for rice cultivation as inorganic fertilizers. In case of upland rice
cultivation, the use of bulky organic manure is very much desirable in order to
maintain the physical condition of the soil and also to increase the water holding
capacity of the soil for maximum utilization of rain water. In upland fields 10-15
tonnes of well rotted Farm Yard Manure or compost should be applied in one
hectare area preferably 4 to 6 weeks before sowing. Organic manures should be
spread evenly on the upper surface of the soil and ploughed in to get it well mixed
in the soil.

Application of fertilizer in transplanted rice field is quite different from

upland rice. A series of reactions-physical, chemical and biological take place
in transplanted rice fields due to presence of excess water in the field. In the
root zone anaerobic environment is formed from aerobic condition due to depletion
of oxygen in the soil profile, which is responsible for gaseous loss of nitrogen
fertilizer due to de-nitrification process. This anaerobic environment also affects
the behavior of phosphorus and micronutrients specially iron and manganese. The
soil in the transplanted rice fields after puddling develops two zones in water
logged conditions. The upper layer of soils (1 to 10 milli metre thick) generally
receives Oxygen periodically from fresh supplies of irrigation water and turns in to
brown colour called "Oxidised zone" and reacts like an unflooded upland soil.
The remaining lower portion of puddled soil without oxygen is called "reduced
zone". When ammonical nitrogen fertilizer is applied in such soils, it gets oxidised
to nitrate (NO3 ) form in the oxidised zone (upper surface layer of the soil).
Afterwards nitrate nitrogen is leached down to the reduced zone and further gets
denitrified to gaseous nitrogen. This gaseous nitrogen is lost. If ammonical
nitrogen is incorporated in to the reduced zone of the soil, where it is held, the
loss can be prevented. Fertilizers containing nitrogen in the nitrate form are more
susceptible to loss of nitrogen through leaching and de-nitrification process.
Therefore, ammonical form of nitrogen is found more beneficial for rice crop.

Water Management

The water requirement of rice crop is comparatively higher than any other crop of the similar duration.
Assured and timely supply of irrigation water has a considerable influence on the yield of the
crop.Duringthecropgrowthperiod,thewaterrequirementisgenerallyhighattheinitialseedling establishment
stage. After the transplanting , water should be allowed to stand in the field at a depth oftwo to five
centimeters till the seedlings are well established. The second,the most important critical stage is tillering
to flowering and in this period the crop should not be subjected to soil moisture stress. The
watersupplyshouldbeensuredinrequiredamountduringpanicleinitiationtofloweringstage.Aboutfive
centimeters depth of water should be maintained in the field up to the dough stage of the crop. Before
harvesting, water should be drained out from the field to allow quick and uniform maturity of grain.

Weed Management

Weed management Weed population is very high in aerobic rice culture due to
non-flooded condition as compared to conventional method of rice cultivation
(flooded condition). That’s why weed poses a bigger threat in aerobic direct seeded
rice system. Preemergence application of pendimethalin (PE) @1.0kgha-1 at 1-2
days after sowing should be done. 2, 4-D Na salt @ 0.80kgha-1 at 25-30 days after
sowing is applied. Two mechanical weeding or two hand weeding is done at 40
and 60 days after sowing (DAS). Pre-emergence application of pendimethalin +
Rice : Dhaincha (1:1) + one (1) hand weeding or 2, 4-D Na salt application
recorded lower weed biomass at 25 DAS of Rice under aerobic condition during
kharif season. At 55 DAS, with or with-out preemergence application of
pendimethalin, 2 mechanical weedings controlled weed population and reduced
weed biomass. Higher weed biomass was observed with higher nitrogen
application at 55 DAS Jana [11].

Weeds of Rice

(i). Grasses,Sedgesandbroadleavesweeds in upland rice:

S.N Botanical Name Common Name Family

Grasses
1. Echinochloa colonum Bansawan Gramineae
Echinochloa crusgali
2. Cynodondactylon Doobgrass Gramineae
3. Eleusineindica Bankodo Gramineae
4. Dactyloctenium Makra Gramineae
Aegyptium
5. Setariaglauca Bottle grass Gramineae
Sedges
6. Cyperusrotundus Motha Cyperaceae
Broadleaves
7. Caesuliaaxillarics Thukaha(Gurguja) Compositeae
8. Ecliptaalba Bhangaria Compositeae
9. Euphoribiaherita Bari dudhi Enphorbiaceae
10. Solanum nigrum Banmakoy Solanaceae
11. Leuccesaspera Gumma Labiatae
12. Phyllanthusniruri Hazardana Euphorbiaceae
13. Lippianodiflora Mokana Verbenaceae
Herbicide for Puddled Transplanted Rice (PTR)

Aerobic Rice Cultivation System

An Eco-Friendly and Water Saving Technology

Definition of ‘Aerobic Rice’ cultivation system Aerobic rice cultivation system

is the method of cultivation, where the rice crop is established by direct seeding
(dry or water-soaked seed) in non-puddle field and un-flooded field condition. The
usual way of planting aerobic rice is the same as we would plant the other cereal
crops like wheat or maize-by direct seeding. It is the most promising approaches
for saving water and labour.
Why ‘Aerobic’ term is used It is grown like an upland crop in soil that is
unpuddle, non-flooded or saturated. The soil is therefore ‘aerobic’ or with oxygen
through the growing season, as compared to traditional flooded fields, which are
‘anaerobic’.

Basic Principles of this System ‘Aerobic rice’ cultivation system is the

methodology, which involves a set of practices for seed treatment, plant, soil,
weed, water and nutrient management.

The basic practices of this system are:

a. Direct seeding of treated seed in non-puddle and non flooded field

b. It can be rain fed or fully irrigated or supplementary irrigated

c. Maintain water at just soil saturation level (aerobic i.e. with oxygen)

d. Effective and timely weed control is crucial for success of this system

e. Row to row spacing should be adopted at 20 or 25cm with continuous sowing

f. Use of best nutrient management practices along with use of

FYM/compost/vermicompost etc.

g. Growing of high yielded varieties

Package of Practices for Aerobic Rice Cultivation Aerobic rice cultivation is a

sustainable rice production methodology for immediate future. Research on
aerobic rice regarding variety development, suitable agro-techniques and different
management practices are going on.

Selection of Suitable Field

a. Select well leveled fields with good drainage facility.

b. Avoid saline/alkaline and inundated low lying fields.

Selection of variety Select most of the popular high yielding varieties (duration:
115-125 days) for the region can be successfully grown under aerobic rice
cultivation. In a pioneering effort in March, 2007, India officially released its
first drought tolerant aerobic rice variety MAS 946-1 followed by MAS 26
(2008) at University of Agricultural Science, Bangalore. Yields were at par with
irrigated puddled rice with an average of 5.5-6tha-1 with 60 percent less water
requirement as reported by Hittalmani [8]. These two first varieties are popularized
for aerobic cultivation in the country.

Seed rate: A seed rate of 50 kg per hectare is recommended for aerobic rice. The
seeds are sown 20 cm between rows and 15 cm within rows with 3 to 5 cm depth

Seed treatment: Treat the seeds with carbendazim @2g/kg seed.

Main Land Preparation At the onset of monsoon with little showers or with the
application of irrigation water if available, field preparation is completed. Initially
plough the field in dry condition 2-3 times and pulverize. Apply well decomposed
cow dung/FYM/compost @4-5t acre-1 before ploughing operation and incorporate
it into the soil thoroughly.

Spacing and sowing Row to row distance is 20 or 25cm with continuous sowing is
to be done. The usual way of planting aerobic rice is the same as how we would
plant wheat or maize or sorghum by dry direct seeding. Line sowing is done during
ideal moisture content of soil.

Irrigation water management Aerobic rice system can be rain fed or fully
irrigated or supplementary irrigated. It can be also grown entirely on rainfall in wet
season with a well distributed rain. Water management is done to keep soil moist
alternate wetting and drying. Maintain water at just soil saturation level by
intermittent light irrigation coinciding with appearance of hair line cracks or
when see the visual condition (sign or symptoms) of the rice plant. Aerobic
rice cultivation can reduce the irrigation by about 40-50 percent when
compared to transplanted rice. Irrigation should be apply according to critical
physiological growth stages of rice crop, viz. 1 DAS (or pre sowing), tillering,
panicle initiation (PI), flowering and grain filling stages, respectively for obtaining
good grain yield particularly during rabi season/boro as reported by Jana]. But, it
needs further research work in depth.

Nutrient management

Well rotten cow dung manure/F.Y.M/compost @5t acre-1 is applied at time of

final land preparation and mixed it with the soil thoroughly. Zinc sulphate (ZnSo4)
is applied @20-25kgha-1, if Zn is deficient in soil for proper soil health
management. N, P2O5, K2O @100-125, 60-40, 60-40kgha-1 is applied. Half dose
of nitrogen, full dose of phosphorus, 75% of potash and full dose of zinc (20-25kg
ZnSo4/ha) as basal and remaining dose of N in two splits (25% N at active tillering
and 25% N along with 25% potash at panicle initiation) are applied

Significance of Aerobic Rice System Aerobic rice is grown like any other crops
like maize or sorghum on dry soils with surface irrigations provided when
necessary with intensive agronomic practices. Compared with flooded lowland
rice, aerobic rice requires 30-50% less water Bouman et al. [4]. Supplementary
irrigation is applied in aerobic rice system of cultivation as and when required and
can be supplied in the same way as to any upland cereals crops like maize, wheat
Bouman et al., Wang et al. [5]. Aerobic rice is a water and labour saving
technology for water-shortage environments. It is a modern production system with
favourable soils and adapted, potentiality high-yielding varieties that are direct dry
seeded. Aerobic rice is not ponded and irrigated similar to other upland cereal crop
and is suitable for water scare environments, and it can stand being periodically
flooded

Advantages of aerobic rice cultivation system

a.Saves labour and water

. b. Direct seeding.

c. Saves seeds.

d. Cost effective.

e. Eco-friendly.

f. No need of puddle operation in field.

g. Aerobic condition in soil.

h. N-use efficiency is more.

i. Cost of cultivation is significantly low.

j. Efficient utilization of rain water.

k. Soil structure is maintained and

l. Improves soil health