`star` Introduction
`star` Understanding Plant Breeding
`star` Main steps in Plant Breeding


● `color{Violet}"Traditional farming"` can only yield a `color{Violet}"limited biomass"`, as food for humans and animals.

● Better `color{Violet}"management practices"` and increase in `color{Violet}"acreage"` can increase yield, but only to a limited extent.

● `color{Brown}"Plant breeding"` as a technology has helped `color{Violet}"increase yields"` to a very large extent.

● `color{Brown}"Green Revolution"` in `color{Violet}"India"` was responsible for our country to not merely meet the national requirements in food production but also helped us even to export it.

● ● `color{Violet}"Green revolution"` was dependent to a large extent on `color{Violet}"plant breeding techniques"` for development of `color{Violet}"high-yielding"` and `color{Violet}"disease resistant"` varieties in wheat, rice, maize, etc.


● `color{Brown}"Plant breeding"` is the `color{Violet}"purposeful manipulation"` of plant species in order to create `color{Violet}"desired plant types"` that are better suited for cultivation, give better yields and are disease resistant.

● `color{Violet}"Conventional plant breeding"` has been practiced for thousands of years, since the beginning of `color{Violet}"human civilisation"`; recorded evidence of plant breeding dates back to `color{Violet}"9,000-11,000 years"` ago.

● Many `color{Violet}"present-day crops"` are the result of `color{Violet}"domestication"` in ancient times.

● Today, all our `color{Violet}"major food crops"` are derived from `color{Violet}"domesticated varieties"`.

● `color{Brown}"Classical plant breeding"` involves crossing or `color{Violet}"hybridisation of pure lines"`, followed by `color{Violet}"artificial selection"` to produce plants with `color{Violet}"desirable traits"` of higher yield, nutrition and resistance to diseases.

● With advancements in `color{Violet}"genetics"`, `color{Violet}"molecular biology"` and `color{Violet}"tissue culture"`, plant breeding is now increasingly being carried out by using `color{Violet}"molecular genetic tools"`.

● `color{Brown}"Traits incorporated in Plants"`:
If we were to list the `color{Violet}"traits or characters"` that the breeders have tried to incorporate into crop plants, the most important to be listed would be:

`star` `color{Violet}"Increased crop yield"`

`star` `color{Violet}"Improved quality"`

`star` `color{Violet}"Increased tolerance to"` `color{Violet}"environmental stresses"` (salinity, extreme temperatures, drought)

`star` `color{Violet}"Resistance to pathogens"` (viruses, fungi and bacteria)


● `color{Violet}"Plant breeding programmes"` are carried out in a `color{Violet}"systematic way worldwide"`–in government institutions and commercial companies.

● The `color{Violet}"main steps in breeding"` a new genetic variety of a crop are –

(3a) `color{Brown}"Collection of variability:"`

● Genetic variability is the root of any breeding programme.

● In many crops pre-existing `color{Violet}"genetic variability"` is available from `color{Violet}"wild relatives"` of the crop.

● `color{Violet}"Collection and preservation"` of all the different wild varieties, species and relatives of the cultivated species (followed by their `color{Violet}"evaluation"` for their characteristics) is a pre-requisite for `color{Violet}"effective exploitation"` of natural genes available in the populations.

● The `color{Violet}"entire collection"` (of plants/seeds) having all the `color{Violet}"diverse alleles"` `color{Violet}"for all genes"` in a given crop is called `color{Brown}"germplasm collection"`.

(3b) `color{Brown}"Evaluation and"` `color{Brown}"selection of parents:"`

● The `color{Violet}"germplasm is evaluated"` so as to identify plants with `color{Violet}"desirable combination"` of characters.

● The `color{Violet}"selected plants"` are multiplied and used in the process of`color{Violet}" hybridisation"`.

● `color{Violet}"Purelines are created"` wherever desirable and possible.

(3c) `color{Brown}"Cross hybridisation among"` `color{Brown}"the selected parents:"`

● The `color{Violet}"desired characters"` have very often to be combined from `color{Violet}"two different plants"` (parents), for example high protein quality of one parent may need to be combined with disease resistance from another parent.

● This is possible by `color{Violet}"cross hybridising"` the two parents to produce hybrids that `color{Violet}"genetically combine"` the desired characters in one plant.

● This is a very `color{Violet}"time-consuming and tedious"` process since the pollen grains from the desirable plant chosen as male parent have to be collected and placed on the stigma of the flowers selected as female parent.

● Also, it is `color{Violet}"not necessary"` that the `color{Violet}"hybrids do combine"` the desirable characters; usually only `color{Violet}"one"` in `color{Violet}"few hundred"` to a `color{Violet}"thousand crosses"` shows the desirable combination.

(3d) `color{Brown}"Selection and testing"` `color{Brown}"of superior recombinants:"`

● This step consists of `color{Violet}"selecting"`, among the progeny of the hybrids, those plants that have the `color{Violet}"desired character combination"`.

● The selection process is crucial to the success of the `color{Violet}"breeding objective"` and requires careful `color{Violet}"scientific evaluation"` of the progeny.

● This step yields plants that are `color{Violet}"superior to both"` of the parents (very often more than one superior progeny plant may become available).

● These are `color{Violet}"self-pollinated"` for several generations till they reach a state of `color{Violet}"uniformity (homozygosity)"`, so that the characters `color{Violet}"will not segregate"` in the progeny.

(3e) `color{Brown}"Testing, release and"` `color{Brown}"commercialisation of new cultivars:"`

● The newly selected lines are `color{Violet}"evaluated for their yield"` and other `color{Violet}"agronomic traits"` of quality, disease resistance, etc.

● This evaluation is done by growing these in the `color{Violet}"research fields"` and recording their `color{Violet}"performance under ideal"` fertiliser application irrigation, and other crop management practices.

● The evaluation in research fields is followed by `color{Violet}"testing the materials"` in farmers’ fields, for at least `color{Violet}"three growing seasons"` at several locations in the country, representing all the `color{Violet}"agroclimatic zones"` where the crop is usually grown.

● The material is `color{Violet}"evaluated in comparison"` to the `color{Violet}"best"` available local crop cultivar – a `color{Brown}"check or reference cultivar"`.