Genetic variability and divergence in rice refer to the differences in the genetic makeup of various rice varieties. Rice is a staple food crop that is widely grown and consumed across the world. The genetic variability in rice is essential for the survival of the species, as it allows for adaptation to different environmental conditions and resistance to various biotic and abiotic stresses.
The genetic diversity in rice is primarily attributed to two factors: natural selection and human intervention. Natural selection has played a crucial role in shaping the genetic diversity of rice over thousands of years, allowing for the development of various ecotypes and landraces that are adapted to different environments. On the other hand, human intervention, including breeding and selection, has also contributed to the genetic variability of rice, allowing for the development of high-yielding varieties with desirable traits.
Genetic divergence in rice refers to the differentiation of the genetic makeup of various rice varieties. This divergence can be measured using various methods, such as molecular markers, morphological characteristics, and agronomic traits. Genetic divergence analysis can help identify genetically distinct groups of rice varieties and aid in the development of breeding programs for crop improvement.
Overall, genetic variability and divergence are crucial for the sustainable production of rice, ensuring the availability of diverse and adaptable rice varieties to meet the ever-increasing demand for this vital crop.
Rice is a nutritious cereal crop, mainly used for human consumption. It is the main source of
energy and is an important source of protein providing a substantial amount of recommended
nutrients intake of zinc and niacin. Rice is an excellent source of carbohydrates and to a certain
extent, it provides protein to the regular human diet. So, it is used as a staple food crop
and eaten as cooked rice and also used for various preparations and commercial and
industrial importance. Besides grains, its straw and rice hulls are used as fodder, mulching,
packing as insulation materials etc. In the 21st century, there will be a need for about 300
million tons of food grains to feed the rapidly increasing population.
Grain quality characteristics are very important in rice breeding as it is predominantly
consumed as a whole grain. The milling percentage, grain appearance, cooking quality and
nutritional components constitute the quality traits. Nutritional components include
proteins and micronutrients like Iron and Zinc. The average percentage of protein in rice
grains is 8 per cent (The amino acid profile shows that it is rich in Glutamic acid and Aspartic
acid, the highest quality cereal protein is rich in lysine (3.8 %), sixth first limiting amino
acid); Fe is 1.2 mg/100 g and Zn is 0.5 mg/100 g. Malnutrition is a large and growing problem in
the developing world mostly in South and S.E. Asia and Sub Sahara Africa Over 3 billion people suffer micronutrient malnutrition Iron
deficiency may affect 3 billion people worldwide It is estimated that 49 per cent of the world's
population is at risk for low zinc intake. In order to enhance the micronutrient concentration in
the grain, suitable breeding programmes should be followed.