Food. Forage, and fodder crops-Rice

Food. Forage, and fodder crops- Rice

Rice

Botanical Name: Oryza sativa

Family: Poaceae (Gramineae)

Common name: Chawal, dhan

Origin and Evolution

Rice is known to have been grown in China nearly 5000 years ago. Archeological studies also indicate that the remains of rice were found in yung shao excavations from China, of 2600 BC. According to de Candolle various wild relatives of rice such as Oryza rufipogan and O. nivara are available in India abundantly. Archaeological remains of rice available from Indus valley excavations also support the fact that rice was grown here before 2300 BC. Nowadays there are two cultivated species of rice viz - O. sativa and O. glaberrima are widely grown in most of the regions. Their close resemblance and availability of their intermediate varieties is an indication of the fact that both the above mentioned species would have originated from a common ancestor Oryza perennis. It spread east ward from India, China and then gradually to Japan, and west ward to Iran, Iraq, turkey and Egypt.

Botanical Characters

Rice is a semi-aquatic annual grass. Plant body is having the height of 50-150 cm. Stem is cylindrical and differentiated into nodes and internodes. In the plant body tuft formation takes place due to the process of tillering. The inter nodes are hollow and of smaller size in the basal region of the plant body but gradually become elongated in the upper regions of the plant. 

Intercalary meristem is present above the each node. The basal leaf of each tiller and main stem is rudimentary and known as protophyll. Leaves are alternately arranged. Each leaf is differentiated into leaf sheath, lamina, ligule, and auricle. Node is partially or completely enclosed by leaf sheath. Lamina is 30-50 cm in length, and 1-2 cms broad. The margins of lamina are hairy. Inflorescence of rice plant is panicle of spikelets. The spikelets are solitary and single flowered. Flowers are usually self-pollinated. 

The flowers are enclosed in lemma and palea and on maturity of plant, they form hull which is attached with grain. The grains of rice enclosed by hull are known as paddy or Dhann Lemma and palea are either owned or awnless. Each flower consists of six stamens (arranged in two whorls and a carpel) which are enclosed by lemma and palea. Grain or fruit is one seeded caryopsis. The grains of rice show variability in size and shape. 

These are either white or yellow coloured. In the cereals maximum amount of starch is found in rice grains as reserve food after barley. Each rice grain contains 78% starch, 7.5% protein, along with 1.8% fat and vitamins.

Cultivation

About 90% of total rice production of the world comes from China, India, Bangladesh, Japan, Pakistan, Myanmar, Thailand, Vietnam, Korea, Philippines, Indonesia and Srilanka. However, the cultivation of rice is also common in Italy, Spain, Egypt and America. China is the country which provides maximum production of the world, India is next in number. India has the largest area under rice cultivation about 29% of the total world. More or less it is practically grown in all states of India. 

However the production of rice in our country is mainly concentrated in the river valleys, deltas and in low-lying coastal areas. The leading rice producing states of India are West Bengal, Uttar Pradesh, Andhra Pradesh, Punjab, Tamil Nadu, Orissa, Bihar, Madhya Pradesh and Assam. Rice is an essentially the crop of tropical climate. However it is grown over extremely wide range of climatic conditions spread over throughout the world, but it is best suited to the regions which have high temperature, high humidity, prolonged sunshine and assured with continuous supply of water. 

An annual rainfall of 60-120 cm is favourable for upland varieties, and 180-240 cm for low land varieties. Before the cultivation, field is thoroughly ploughed. Usually the field is having the soil of high water holding capacity and good water drainage. After the proper ploughing the field is flooded with water. However in the non irrigated areas the paddy cultivation process is started when these fields are filled by rain water. The sowing process of rice is undertaken at varied times in different parts of India depending on the climatic conditions. On the basis of harvesting period rice is placed under three categories. These are:

(1) Winter rice: This variety is sowed in the months of June-July and its harvesting is undertaken in November-December. This is mainly a crop of low lying areas and known as Aman.

(2) Autumn rice: This variety is sown in May-June and harvested by September- October. It is mostly cultivated in highlands.

(3) Spring rice: It is sown in December-January and harvested by March- April. Two main systems for cultivation of rice are followed in India:

(a) Dry Cultivation: Similarly to other cereals in this system, the crop is raised on dry soil. The field is repeatedly ploughed and harrowed in the summer season to obtain the sufficient tilth. The field is ploughed five to seven times at an interval of seven days. Then the seeds are sown by broadcasting, dibbling or drilling in lines. The method of sowing in lines is mostly preferred as it ensures a uniform stand, requires a lower seed rate and facilitates inter culture operations. In this method line to line distance is kept 20-25 cm.

(b) Wet Cultivation: In this system of cultivation the crop is grown under an

assured, sufficient and adequately regular supply of water and the plants remain flooded by water from the time of transplanting under harvesting. Wet cultivation system covers about 90% of rice cultivation in India. The land is thoroughly ploughed and puddled with 5-6 cm of standing water, under this system. The major aim of puddling is to get a soft soil so that transplanted seedlings can establish themselves adequately and quickly. Now this wet field is repeatedly ploughed 4-6 times with an interval of four to five days between two ploughing and then leveled up by planking. 

Here in this system, either the sprouted seeds are directly sown in a puddle or leveled field or alternatively seedlings are grown in a nursery and then transplanted. In the traditional rice growing areas where there is properly favourable rainfall, temperature and humidity are observed, the seedlings are grown on raised seed beds. Besides the two above mentioned systems of paddy cultivations, there is yet another system, known as semi dry system, where in the beginning the rice is sown as dry crop but later on rain water is impounded in the field when the crop is 5-6 weeks old. This practice is known as "Bushening", and quite prevalent in Orissa and Madhya Pradesh. 

This process of ploughing the field with the standing crop serves three purposes weeding, thinning and inter-culturing of the crop. The high yielding varieties of rice require sufficient amount of proper fertilizers. 30-45 days before sowing about 100-110 kg/hectare green manure is applied to the field. Then after sowing 100-110 kg super phosphate and 200 kg ammonium sulphate per hectare is applied.

Harvesting and Threshing

When culms of the crop plants turn brown or yellow, the crop is considered to be ready for harvesting. The premature harvesting decreases the crop yield and also affects the milling quality. On the other hand in the delayed harvesting, there are chances of loss of grains by shattering. The task of harvesting is carried out by the help of hand sickles. After it, the harvested crop is dried immediately and threshed. Normally threshing is done by beating the sheaves or by trempling under the feet of bullocks. In some regions, the threshing is done by machines also, pedal and power threshers are used for this purpose. After the threshing grains are winnowed and properly dried before bagging. The rice grain covered by husk, as we know is known as paddy. This husk is separated from the grain by beating. After the separation from grain it is known as bran.

Uses

1. In various countries such as India, China, Japan, and Korea, rice is used as major or staple food. Since its bread or chapatti cannot be prepared because of glutinine deficiency in the grains hence it is taken directly as food after cooking or boiling.

2. Various food delicacies such as Idli, Dosa and Upma are prepared after

Fermentation generally in most of the parts of our country, but particularly in

South India.

3. Rice is also used in the preparation of biscuits, ice-cream and pastry.

4. It is also used for making alcoholic beverages and as a source of starch.

5. Rice starch is widely used in cosmetic industry, as thickener in calico printing, in the finish of textiles.

6. Rice starch is also used for making dextrins, glucose and adhesives.

7. Paddy husk is used as a fuel and for making hard boards and as a raw material for alcohol and furfural.

8. Rice bran is used as cattle feed.

9. Edible fatty oil is also obtained from rice, bran, which is known as "bran oil".

10. It is used in soap industry and for making cosmetics.

11. Paddy straw is used as a fodder, in the manufacture of straw boards, and as soil mulch. Not only is this but also used for thatching, making hats, sacks, mats ropes and baskets.