Questions and Answers
What is the chromosome number of rice?
Which of the following statements accurately describes the protein content in rice?
Which rice species is primarily cultivated in tropical West Africa?
Which region is suggested as a probable center of origin for cultivated rice?
Signup and view all the answers
What is the main use of rice bran?
Signup and view all the answers
Which of the following by-products of rice milling is used for insulation?
Signup and view all the answers
How much oil can be recovered from rice bran?
Signup and view all the answers
What event is considered the oldest sample of rice grains?
Signup and view all the answers
Which of the following is NOT a sub-species of rice (Oryza sativa)?
Signup and view all the answers
How is rice typically categorized in terms of energy content?
Signup and view all the answers
Study Notes
Rice Overview
- Botanical name: Oryza sativa L.
- Chromosome count: 2n = 24
- Major energy source: staple food for a significant portion of the global population.
- Protein content: 6-7% in milled rice, lower than wheat but with high biological value.
- Fat content: low at 2.0-2.5%, much of which is lost during milling.
- B vitamins: rice contains as much as wheat.
- Calcium content: low in rice.
- By-products of milling have various uses.
Rice By-products
- Rice bran: utilized as cattle and poultry feed and for oil extraction; comprises about 8% of paddy weight and contains 15-20% oil.
- Recoverable oil from rice bran is approximately 15%.
- Global rice bran oil production ranges between 1-1.4 million tonnes, with India contributing 0.7-0.9 million tonnes.
- Rice hulls: repurposed for insulation materials, cement, cardboard, and as poultry litter.
- Rice straw: serves as cattle feed and winter litter.
Cereals Definition
- Definition: crops in the family Gramineae grown for edible starchy grains called caryopsis.
- Etymology: the term 'cereals' derives from Ceres, the Roman Goddess symbolizing the 'Giver of Grains'.
Origin of Rice
- Out of 24 species of the genus Oryza, only Oryza sativa and Oryza glaberrima are cultivated.
- Oryza sativa: cultivated in all rice-producing areas; Oryza glaberrima is specific to tropical West Africa.
- Relatives of O. sativa include wild perennial O. rufipogen and annual O. nivoroo.
- Relatives of O. glaberrima include wild perennial O. longistominata and annual O. barthii.
- Oldest rice grains excavated at Hastinapur, India, dated to 1000-750 B.C.
- Suggested centers of origin:
- Southwest Himalayas indicates diverse types and probable origin.
- Studies by De Candolle (1886) and Watt (1862) mention South India as a center of origin.
- Vavilov proposed India and Myanmar as major centers for cultivated rice.
- D. Chatterjee (1948) suggested two centers of origin: Southeastern Asia (including India, Myanmar, Thailand) and West Africa.
Genetic Classification
- Rice varieties classified into three sub-species:
-
Indicas: traditional tropical varieties characterized by:
- Long duration growth cycle and photosensitivity.
- Tall, weak stem structure and susceptibility to lodging.
- Lower responsiveness to heavy fertilization.
-
Indicas: traditional tropical varieties characterized by:
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
This quiz covers essential facts about rice, including its botanical classification, nutritional content, and significance as a staple food worldwide. Explore the details of rice's composition, including proteins, fats, and vitamins, as well as the implications of rice milling by-products.
