Selection

It is a process of selective improvement of a crop. In selection, a plant is selected based on its genotypic and phenotypic characters in order to improve some of its characters in its next generation.

Natural selections have occurred in many crops, where some characters were retained and some others rejected by nature. In the process of agricultural development over centuries, many crops or their varieties were selected in order to improve specific character in future generations. Farmers, early scientists, naturalists have preformed the process of selection in many crops. Actual selection process involves selecting a desirable variant among genetically divergent crop and allowing it to reproduce - in order to consolidate and intensify a specific desirable character. Selection may have to be done over many generations rejecting the undesirable variants at every stage.

Most of the crops and their varieties are the product of selections made by our ancestors. In fact early history suggests that cultivated species were evolved from wild species through the process of selection. Criteria for selection may be different in different crops or different objectives.

Crop	Criterion for selection	Objective
Rice	More spikelets / panicle, bold spikelets, larger panicle	Increasing yield
Cotton	More number of fruits/ plant, Bigger fruit size Longer fibre, more maturity of fibres.	Increasing yield Quality of fibre
Mango	Less fibre, more sucrose, fructose, higher pulp ratio	Pulping quality More palatability
Tomato	More juice, thin skin	Better processing value
Coconut	Bigger nut, thicker kernel	Higher yield / more oil
Wheat	Higher protein content awnlessness	Better nutritional value easy post harvest process

Selection of crops and their varieties has made profound impact in improvement of crop - in respect of productivity, quality, market acceptance, industrial value, and disease control as well as wide adaptability to varying climates and soils.

Selection is either used singly or in combination with other methods of crop improvement to bring and consolidate desirable characters in varieties. It has been widely used in self pollinated and cross pollinated crops - both in annual and perennial crops.

There are many types of selections adopted in different crops. Out of them, two are important.