Oryza sativa, commonly known as the Asian rice, is the botanical name of rice.
Oryza sativa is the edible starch cereal grain. It belongs to the grass plant family Poaceae by which it is produced. Rice is the most widely grown tropical cereal. Over 400 million tons of milled rice is produced each year. Roughly one-half of the world population depends upon rice as a staple food.
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Oryza sativa is a grass with a genome consisting of 430mb across 12 chromosomes. Rice occurs in a variety of colors including brown, white, back, purple, and red rice.
Kingdom − Plantae
Division − Magnoliphyta
Class − Liliopsida
Order −Poales
Family − Graminae/Poaceae
Tribe − Oryzae
Genus − Oryza
Species − sativa
Rice is an important staple food crop for more than 60% of total population.
Rice straw is used for thatching roof and for the preparation of hats, mats, ropes etc., in cottage industries.
Rice husk is used as fuel source, animal feed source and for paper making.
Rice straw is used for ripening fruits, packing materials, manufacture of straw boards etc.
Rice bran is used in poultry feed and animal feed.
Defatted bran is a rich source of protein can be used for the preparation of biscuits and cattle feed.
Among the rice growing countries, India has the largest area followed by China and Indonesia. In terms of production, India ranks second next to China. Based on productivity, Egypt ranks first followed by USA. Rice is cultivated almost all the states in India; however, Uttar Pradesh and West Bengal have the highest production of rice. Whereas Punjab has the highest yield per unit area.
Oryza sativa is majorly divided into two varieties, namely −
Non-Sticky Long Grained Indica Rice
Sticky Short Grained Sinica or Japonicas.
Indica is grown around the Ganges and its varieties are mainly lowland varieties of rice grown mostly throughout tropical Asia. Japonica was domesticated in Yangtze valley and its varieties are usually cultivated in dry fields in temperate East Asia and high elevations in South Asia, and upland areas of South East Asia.
A third variety of rice, called Javanica, which is a grained and thrives under tropical conditions has been identified based on morphology.
Rice grows in warm and humid climate, but it is best suited to regions which have sufficient supply of water, prolonged sunshine, and high humidity. It requires temperature between 200c to 300c (at blooming stage: 26.50c to 29.50c and at the time maturity − 200c to 250c), and a well distributed rainfall of about 100cm or good irrigation facilities.
Rice is generally cultivated in almost all types of soil. Soils having a pH range between 5.5 to 6.5 is best suited for rice cultivation.
Rice is a semi-aquatic crop that can be grown in soils having good water retention capacity with good amount of clay and organic matter. Clay or clay loams are most suitable for rice cultivation. This is because such soils have the highest water holding capacity, and thus sustains the crop.
Paddy comes under Kharif crops which are sown in the rainy season. The rainy season in India is generally from June to Depending upon rainfall, temperature and other climatic conditions, rice growing seasons vary in different parts of India.
| Crop Season | Local Name | Sowing Time | Harvest Time |
|---|---|---|---|
| Kharif | Aus rice | April - May | Sept - Oct |
| Rabi | Aman rice | June - July | Nov - Dec |
| Spring | Boro rice | Dec - Jan | March - April |
In India, rice is grown mainly on two types of soils. They are as follows −
Wet or low land cultivation− This system of rice cultivation is practiced where there is an adequate supply of water.
Dry or semi dry upland cultivation − This method of rice cultivation is practiced in water deficient areas.
The most suitable soil for the cultivation of Rice are clay and loamy soil. Clay and loamy soils can easily puddle into mud and the soil develop cracks in drying condition. Paddy farmers get their fields ready before rainy season. The weeds are cleared and the field is ploughed by buffaloes or tractors to a depth of few inches. Then, fertilizers and manures are added to the soil and the whole surface of the soil kept covered with water and the field is then ready to receive seedlings.
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Generally, paddy seedlings are grown in nursery and are transplanted into fields after 45 days. Rice seedlings can either be transplanted manually or by machines. In some areas of Sri Lanka and India, seeds are sown directly and the seedling sprouts when the rain comes.
Paddy fields require regular maintenance such as thinning out the more crowded patches, occasional weeding, etc. The level of the water should be maintained in accordance with the growth of plants and fields are drained dry before the crop is harvested.
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Rice crop is harvested as soon as it matures. Timely harvesting ensures good grain quality, consumer acceptance, etc. Harvesting in our country is either done manually by sickle or by a machine called harvester. The right time of harvest is when the grains are golden yellow colour or ripened in a percentage of 80-85%.
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After harvesting, the grain seeds need to be separated from the chaff. Threshing is done either by manually or by machine. Farmers with small holdings of land use winnowing Machine for the separation of grains. Now-a-days threshing can be done with the help of a machine called ‘combine’ which is in fact a harvester as well as a thresher.
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If the harvested rice seeds are to be kept for longer time, proper storage is necessary to protect them from pests and microorganisms.
Harvested seeds contain moisture content and the seeds are stored without drying, they may get spoilt. So, before storing them, the grains are properly dried in the sun to reduce the moisture content and thus by preventing attack of insects, pests, fungi, etc.
Silos and granaries are used to store rice grains so as to protect it from pests like rats and insects.
Different varieties of rice cultivated in India are −
Jeera Samba
Kalanamak, Ponni
Basmati
Ambemohar, etc.
Rhizoctonia solani causes sheath blight, a fungal disease. At the tillering to heading stage, the illness is more noticeable.
Helminthosporium oryzae causes Brown Spot, a fungal infection. This can infect crops at any stage of development, although it is most dangerous from maximum tillering until maturity.
Sarocladium oryzae is the fungus that causes sheath rot. When this happens late in the booting process, it can be extremely destructive.
Pyricularia oryzae causes rice blast, a fungal disease. This disease can affect paddy at any stage of growth and all parts of the plant’s aerial components (Leaf, neck, and node).
Q1. Origin place of rice is−
a. South East Asia
b. USA
c. Indo-Burma
d. Both a and c
Ans: d. Both a and c
Q2. Sowing time of Boro rice is−
a. November - December
b. December - January
c. October
d. July – August
Ans: b. December – January
Q3. Scientific name of rice is −
a. Oryza sativa
b. Oryza glaberima
c. Both a and b
d. None of these
Ans: a. Oryza sativa
Q4. The first step before growing crop is__________ of the soil. −
Ans: preparation of soil.
Q5. Define Kharif crops.
Ans: The crops which are sown in the rainy season are called Kharif crops..
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