Question

Write short note on:
(i) Biofortification
(ii) Hybrid Vigour

Answer 1

(i) BIOFORTIFICATION:

The breeding methods are used to produce crops with high levels of vitamins, proteins and minerals that can improve public health. This is called biofortification.

The objective of breeding for improved nutritional quality is to improve:

1. Protein content and quality

2. Oil content and quality

3. Vitamin content

4. Mineral content

In 2000, maize hybrids were developed which in comparison to existing maize hybrids, had twice the amino acids tryptophan and lysine. A wheat variety Atlas 66 is developed having high protein content and is being used for improving cultivated wheat. It has been made possible now to develop iron-fortified rice variety that has five times more iron than the consumed varieties. Many other crops like Vitamin A enriched carrots, spinach, Vitamin C enriched mustard, tomato and calcium enriched bathua have been developed by The Indian Agricultural Research Institute, New Delhi.

(ii) Hybrid vigour

Hybrid vigour is also known as "heterosis". It is the phenotypic superiority of a hybrid in its traits over its parents. Generally, hybridisation between unrelated strains leads to an increased vigour and fertility, thus hybrid vigour or heterosis. The term "heterosis" was given by Shull in 1914 but it was first studied by Kolreuter in 1763 and then by Darwin in 1876. Inbreeding or self-fertilisation leads to loss of heterosis. Generally, it is expressed as an increase in size and yield but it may also be expressed in other ways like earlier or later flowering, greater adaptation, faster growth etc. Heterosis is commercially exploited for many crop species, vegetables, fruit trees and in animals.