Breeding of Vegetable, Spice and Tuber crops (2+1)

History of hybridization

• In comparison to selection, hybridization is of more recent origin.
• There is evidence that Babylonians and Assyrians hand-pollinated date palm as early as 700 B.C. for metaxenic effects of pollen.
• Metaxenia is the effect of pollen on the maternal tissues of fruit. Clearly, the artificial pollination in this case was not for the purposes of crop improvement.
• Sex in plants was discovered by Camararious in 1694. In 1717, Thomas Fairchild produced the first artificial hybrid, the Fairchild’s mule, by crossing sweet William (Dianthus barbatus) with carnation (Dianthus caryophyllus).
• Subsequently, a large number of scientists used hybridization for scientific studies as well as for crop improvement.
• Notable among such scientists are, Joseph Kolereuter, who made many crosses in tobacco during 1760-1766, and emphasized hybrid vigour in F1.
• Thomas Andew Knight ,who developed several varieties of apples, pears, peaches, grapes and currants during 1759-1835; and Goss, Sargaret, Gaertner and Naudin, who had noted uniformity in F1, dominance in F1, and segregation and appearance of parental types in F2.
• But it was left for Mendel (1865) to propose the clear-cut laws of inheritance of qualitative traits. These and subsequent discoveries in genetics have given hybridization a scientific basis.
• Towards the end of nineteenth century, hybridization was widely used for crop improvement.
• With the help of genetic principles, the breeder is able to predict the kind of progeny he is likely to obtain from a given cross.
• Therefore, he can plan the crosses from which he is most likely to obtain the desired plant type.
• Today, hybridization is the most common method of crop improvement, and the vast majority of crop varieties have resulted from hybridization.