Self -sterility 159 



were satisfactory, although in some years the bloom of some 

 of these may not be simultaneous although it overlaps. 



Grapes of the muscadine type are strongly self-sterile, 

 having imperfect flowers. (Cf. Reimer and Detjen, Bull. 

 No. 209, N. C. Exp. Sta.) Beach finds (Bull. No. 223, N.Y. 

 Exp. Sta.) that varieties of grapes self-sterile or nearly so 

 have shown about as little ability to fertilize other self- 

 sterile sorts as they have to fertilize themselves; and 

 also they have usually failed to fertilize self-fertile varie- 

 ties. Indications were found, however, that the pollen in 

 some instances is not altogether impotent, but that its own 

 pistils are less congenial than those of some other varieties. 

 Further investigation is needed to learn whether this self- 

 sterility is because the pollen is deficient in amount, is 

 not well developed, or is uncongenial to its own variety. 



For Oregon conditions, Lewis and Vincent have found 

 (Bull. No. 104) gains in size of fruit of self-fertile apples 

 to result from crossing, as well as marked benefits from 

 crossing self-sterile kinds. Of eighty-seven varieties of 

 apples under test, fifty-nine varieties were found to be 

 self-sterile, fifteen varieties self-fertile, and thirteen varie- 

 ties partially self-fertile. "Many varieties of apples 

 naturally tend to be self-sterile, when limited to their own 

 pollen. Results indicate that cross-pollination is the rule 

 and self-pollination the exception. In some instances the 

 immediate effects of pollen on the color of the fruit were 

 perceptible. With an increase in the weight of the crossed 

 apple, there was a proportional increase in the weight of 

 the seeds. The action of foreign pollen on the Yellow New- 

 town, a self-fertile variety, was very pronounced. Many of 

 the self-fertile varieties of apples, when self-pollinated, 

 were found to be seedless, or devoid of plump seeds. Wind 

 is a poor agent in transferring pollen from tree to tree. 



