CHAPTER XVIII 

 FRUIT BREEDING 



The improvement of fruit crops offers an interesting field of 

 study for the trained investigator. Many fruits are in a complex 

 heterozygous condition. For this reason and because fruits are 

 propagated by asexual methods Mendel's law does not have here 

 the same value as for the breeder of self -fertilized crops. There 

 are also many fruit crops which are totally self -sterile so that 

 cross-pollination, either natural or artificial, is essential to the 

 production of fruit. Unlike an annual crop the individual fruit 

 tree often takes many years to grow before fruiting. For these 

 reasons methods of handling are often of much greater importance 

 than methods of breeding. It is, therefore, of utmost importance 

 that the student first make an intensive study of the botanical 

 relatives, methods of culture, varieties, and environmental 

 necessities of the crop before undertaking breeding operations. 



ORIGIN AND ANTIQUITY OF SOME FRUITS 1 



Wild fruits without doubt played an important role in the 

 food supply of primitive man. As the art of agriculture came 

 to be developed because of the necessity of obtaining enough 

 food to supply the increasing human population, the fruit crops 

 were gradually introduced into cultivation. Some of our most 

 prized fruits, as the apple, grape, and plum, have been cultivated 

 since earliest times; while others, as the strawberry, black rasp- 

 berry, and blackberry, have been brought under cultivation 

 since America was discovered. 



The wild species from which our fruits have been developed 

 may still be found today. Wild plums may be found in nearly 

 every state of the United States, while in central and northern 

 Asia the wild relatives of apples, pears, apricots, cherries, and 

 plums are of frequent occurrence. 



The wild crabs are found in abundance, in both the Eastern 

 and the Western Hemispheres. As the cultivated European 



1 A paper by WHITE (1916) has been used very freely in this discussion. 



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