Cultivation and improvement of Rice

Origin of Rice:-

1. Introduction:-

· Common Name:- Paddy, Rice

· Botanical Name:- Oryza sativa

· Family:- Poaceae or Gramineae

· Chromosome Numbers:- 2n = 2x = 24

2. Species:- Genus Oryza has total 24 species. 22 species are wild and 2 species are cultivated. Cultivated species are:-

a. Oryza sativa:-

· This is main cultivated species.

· It is cultivated all over the world.

· It has 3 main sub - species:-

i. indica:- In warm areas

ii. japonica:- In cold areas

iii. javanica:- In intermediate areas (In Indonesia)

· Above mentioned sub - species have morphological, physiological and genetic variations.

b. Oryza glaberrima:-

· It occurs in warm areas.

· It is cultivated in West Africa.

· Gradually, it is being replaced by the Oryza sativa species.

3. Center of Origin:-

· Oryza sativa is also called as "Asian Rice" because it originated in south Asia and South East Asia. It is originated from a perennial wild species 'Oryza rufipogon'.

· Oryza glaberrima is also called as "African Rice" because it originated in West Africa.

Cultivation of Rice:- Rice, Oryza sativa, the staple food of majority of the Indians, is grown practically all over India.

1. Cultivation Area:- The major states of rice cultivation are West Bengal, Bihar, Maharashtra, Orissa, Tamil Nadu, Uttar Pradesh, Madhya Pradesh, Andhra Pradesh, Assam.

2. Soil:- Rice grows well in clays or clay-loams. For normal growth of the crop soil pH between 5 to 8.5 is suitable.

3. Climate:- Following climatic conditions are suitable for rice cultivation:

4. Cropping Season:- Depending on the type of rice, cropping season vary:

5. Rotation:- Rice is grown in rotations with jute, wheat, potato, pulses, oil-seeds, vegetables, etc.

6. Preparation of Land:-

> The preparation of land depends upon whether the crop is to be grown under the ‘dry’, ‘semi-dry’ or the ‘wet’ system.

> In dry-system, the land is ploughed well; weeds and stubbles are collected and burnt; manures are applied well in advance before sowing.

> In wet-system, the land is irrigated before sowing and then ploughed in standing water. Finally ladder is used to level the field.

7. Sowing:-

> Under dry-system of cultivation improved, pure, viable seeds are sown directly by broadcasting or drilling in lines.

> For broadcasting, seed rate varies from 80-100 kg/ha and for line sowing from 60-70 kg/ha.

> In wet-system of cultivation, the crop is generally grown by transplantation.

> For transplanted crops, the seedlings are raised in nurseries.

> Generally 2-3 seedlings of 3-5 weeks age are transplanted in each hill.

> Normally early varieties are planted 20 cm from line to line and 10-15 cm from plant to plant, while medium and late varieties are planted with 20 cm x 15 cm and 23 cm x 23 cm spacing’s respectively.

The sowing time for different types of rice is as follows:

8. Manuring:-

> Chemical fertilizers and organic manures are equally important for rice cultivation.

> Nitrogen, either in organic or inorganic form, is the best manure for rice.

> Farmyards manure, compost, oil-cakes, fish manure and green twigs are commonly used in India.

> 10-15 tonnes of well-rotted farmyard manure/ha is recommended at the time of land preparation.

9. After-care:-

> In field, water is allowed to stand a depth of 1.2-2.5 cm until transplanted seedlings are well established. After this, 5 cm of water with frequent draining and re-irrigation is maintained in the field till 1 or 2 weeks before harvesting. Few weeding should be given and soil near roots of plants should be stirred.

10. Disease and Control:- Important rice diseases and their controlling measures are as follows:

Pest and control: Important rice pests and their control are:

11. Pest and Controlling Measures:- Important rice pests and their control are:

12. Harvesting:- The crop is harvested when the ‘ears’ are nearly ripe and the colour of the straw is still slightly green. Crop is cut with sickles, dried in the field for 2-4 days and stacked in the threshing yard.

The harvesting time for different types of rice is as follows:

13. Threshing:- The crop is then threshed either with sticks or by beating against a wooden log or by treading the entire crop under foot of bullocks or by pedal and power threshers. Finally husk is removed by pounding method or by rice hullers.

14. Storage:- Cleaned un-husked paddy is dried and stored in jute bags and granaries.

15. Yield:- The yield of paddy varies according to the type:

Improvement of Rice:-

1. Pollination:-

Ø Each spikelet remains open for 30 minutes and then closes.

Ø Immediately after the opening of the spiky, dehiscence of anthers takes place.

Ø The receptiveness of the stigma lasts for a day.

Ø There is air pollination or anemophilly occurs in the paddy, so it has versatile anthers.

Ø Paddy is a self-pollinated crop. It has less than 2% cross pollination.

2. Breeding Objectives:-

a. Higher Yield:- In paddy yield depends on 4 factors -

i. Length of panicle

ii. Number of grains per panicle

iii. Test weight

iv. Number of panicles in per unit area

b. Quality of Grains:- The export of fragrant Basmati paddy is of greater economic importance. Quality has 3 characteristics -

i. Cooking Quality

ii. Milling Quality

iii. Processing Quality

c. Disease Resistance:- Several types of diseases can occur in the paddy crop which can cause economic loss. Developing resistance against these diseases is also objective of plant breeding.

i. Blast

ii. Leaf Blight

iii. Stem rot

iv. Brown spot

v. Virus diseases:- Rice Tungro Virus, Grassy Stunt Virus

d. Insect Resistance:- Several types of insect pests can cause damage to the paddy crop which leads to economic loss. Hence one objective is to generate resistance against these insect pests.

i. Stem Borer

ii. Brown Plant Hopper

iii. Gall Midge

iv. Rice Gundhi Bug

v. Rice Mealy Bug

e. Hybrid Rice:- Development of hybrid rice is a major part of Rice Breeding Program in India.

f. Improved Plant Type:- Efforts are being made to develop more efficient ideotypes in IRRI Philippines and Japan.

3. Breeding Methods:-

a. Introduction:-

· IR – 8:- Imported from IRRI, Philippines to India (1968)

· Ch – 1039:- Imported from China to Kashmir

· Norin – 18:- Imported from Japan to Himachal Pardesh

· Mahsuri:- Imported from Malasia to Andhra pardesh

b. Pure line Selection:-

· SR26B:- Salt resistant variety

· FR43B:- Flood tolerant variety

c. Mutation Breeding:-

· Mutagens:- EMS, NMH, NEH, EI, EO

EMS = Ethyl Methane Sulfonate

NMH = n - nitroso - N - methylurea

NEH = n - nitroso - N - ethylurea

EI = Ethylene Imine

EO = Ethylene Oxide

· Procedure:- The seeds are soaked in water for 20 hours. Then immerse the seeds in a mutagen solution for 8 hours. After that, their seed treatment is done.

· Main varieties developed in India: -

i. IIT – 48

ii. IIT – 60

iii. Jagannath

d. Heterosis Breeding:-

· Varieties developed in china:-

i. Shan You 63 (35%)

ii. Shan You 64 (6%)

iii. V – 64 (4%)

· Varieties developed on IARI in India: -

i. Pusa RRH – 10

ii. Basmati – 370

iii. Pusa – 150, 443, 449, 506, 523

iv. Pusa Basmati – 1121 (Variety developed for the state of Delhi in 2003)

v. Unnat Pusa Basmati – 1 (Bacteria resistant variety developed in 2007)

vi. Pusa Basmati – 6 (Anti-collapse variety developed in 2008)

vii. Pusa Sugandh – 2, 3, 5 (Early maturing varieties)

e. Variety Hybridization:-

· This is the most popular and the most successful method.

· In this, one variety is hybridized with another.

· In this, the cross of the indigenous variety is made with the exotic variety.

· In this, mostly pedigree method and sometimes back cross method is used.

· Examples:- Birsa Dhaan - 12, CSR - 10, Shakuntala, Jitendra, Punendra, Chenav, Mahamaya, Nidhi

f. Distant Hybridization:-

· This method is used to transfer disease resistant genes into crop plants.

· In this method,the cultivated species is crossed with the wild species.

· Example: - For tungro virus resistant, the cultivated species Oryza sativa is hybridized with wild species Oryza nivara.

g. Cellular and Molecular Breeding:-

· The IR49830 - 7 variety has been developed by transferring the Sab - 1 gene from donor variety FR - 13A into the receptive variety Swarna. The IR49830 - 7 variety has submerged resistance property.

· Other varieties: - Mehsoorie, Savitri

4. Golden Rice:-

· It was developed by the German scientist Ingo Potrykus.

· It is transgenic plant.

· It is made by transferring β - carotene to the endosperm of the paddy seeds. β - Carotene is a precursor of Vitamin - A, also known as Provitamin - A. β - Carotene is yellow in color which gives yellow or golden color to paddy seeds.

5. Research Institutes:-

· NRRI (National Rice Research Institute):- Cuttack (Odisha)

· IIRR (Indian Institute of Rice Research):- Hyderabad (Telangana)

· IRRI (International Rice Research Institute):- Los Banos (Philippines)