POLLINATION AND FERTILIZATION 179 



pollinate a number of flowers with pollen from the same variety. In 

 the same way, pollinate stigmas on some branches with pollen obtained 

 from other varieties. Rebag and label the twigs. Make records and 

 notes carefully. Later in the season obtain the percentages of fruit 

 set in the different cases. From the results determine what pollen 

 produced the best set of fruit and what varieties would appear to do 

 best when inter-planted. 



EXERCISE VI. Blooming periods. 



Materials. Various kinds of orchard trees in spring time. 



Procedure. Keep blossoming records in a tabulated form for 

 different varieties of fruits in your locality. Record the following facts 

 for each variety: 



a. Date when buds show first signs of swelling. 



b. Date when color of petals shows distinctly in bud. 



c. Date when flower-buds are right for emasculating (just before 

 petals open). 



d. Date when flowers are wide open, that is, when tree is in full 

 bloom. 



e. Date when most of the petals fall. 



By some kind of a diagram indicate the blooming periods of the 

 different varieties so that it may be seen at a glance just how far the 

 varieties overlap so as to be useful for inter-planting for purposes of 

 pollination, assuming that the varieties are inter-fertile. 



EXERCISE VII. Project exercise. If the student has access to a 

 tree of relatively poor bearing qualities, he may make it his study to 

 ascertain: (a) whether or not the tree produces viable pollen; (b) how 

 the viability of its pollen compares with that of good bearers of the 

 same variety; (c) whether or not the tree is self -sterile; (d) whether 

 there is any other variety suitable and near enough to pollinate it; 

 (e) whether or not pollination by any other variety increases its fruit- 

 bearing capacity. 



If there is some obvious reason why the tree is a poor bearer, such as 

 poor location, presence of insects or blight, or lack of care, such an 

 exercise would be wasted. Otherwise its results, if carefully obtained, 

 may prove of great interest and value. 



