Polyploidy is the change in the basic number of chromosome set in any individual species. These are autopolyploids and allopolyploids. It ranges from triploid to octaploids. It may be induced in plants for economic benefit of mankind and environment.
Polyploidy in plants is about one and half of total plant species. These plants are commercially more valuable than the corresponding diploids or halploids.
i. Polyploid plants produce larger sized flower and fruits
ii. Flower more brightly coloured showy than the diploids.
iii. Polyploids are of high nutrient content high ocntent of is usually found in fruits of tetraploid fleshy fruits.
iv. Tetraploids shows tendency towards perenniality rather than annual.
By induction of Polyploids economic value of crops and vegetables are enhanced and evolved varieties of crops are formed polyploid plants are better in quality taste yield nutritional value and sugar content Polyploids are disease resistance.
Knowledge of polyploidy is of great help in plant breeding to originate new evolved and economically important varieties.
i. In Nicotiana resistant variety is formed by using polyploidy.
ii. Use of polyploidy in wheat breeding results in the production of einkorn, emmer and Vulgare varieties of wheat which are polyploids are better of better quality.
iii. Intergeneric and interspecific breeds are evolved by polyploidy of great economic value.
Among ornamental plants various polyploid verity of rose dahlia and others are of outstanding attraction in comparison to other normal diploids.