TESTING GRAPE VARIETIES IN THE VINIFERA REGIONS. 27 



The term "congeniality" as used in this discussion is limited to 

 the relation of vine varieties to the resistant stocks upon which they 

 are grafted. To discriminate properly between adaptability and 

 congeniality and then to determine the congeniality, it is necessary 

 to know the behavior of the resistant varieties as well as the Vinif- 

 era varieties on their own roots. If we have grafted vines of which 

 both the stock and the scion varieties are known to be suited to the 

 soil and climatic conditions and they do not respond, we know that 

 congeniality is lacking. 



The adaptability of varieties can be closely forecasted, but their 

 congeniality must be determined by actual tests. Without knowl- 

 edge of its adaptability to existing conditions, the extent to which 

 differences in the behavior of a variety grafted on different stocks 

 are due to congeniality or to adaptability is impossible of determi- 

 nation. | 



Saccharine and acid determinations of the fruit from grafted vines 

 have been made for a number of years with a view to ascertain 

 whether the quality of the fruit is influenced by the stock upon which 

 the vine is grafted. (See PI. X.) Such determinations contrasted 

 with the same season's growth ratings of the same vines indicate a 

 close correspondence between these important chemical constituents 

 of the fruit and the congeniality of grafts and stocks as determined 

 by observations, and they afford a useful check on the congeniality 

 ratings. 



Similar growth ratings of a variety grafted on various stocks are 

 found to be accompanied by fairly definite percentages of sugar and 

 acid. Under like conditions of growth the sweetness and the acidity 

 of the fruit, as well as its time of ripening, are materially influenced 

 by the congeniality of the scion and stock. The saccharine and acid 

 contents are two of the leading considerations in the money value of 

 the fruit. 



In determining the relative congeniality of vine varieties on diverse 

 resistant stocks, these and the relative quantity of fruit produced, 

 the difference in time of ripening, the relative healthfulness and com- 

 parative durability of varieties on different resistant stocks, and the 

 relative amount of wood produced are some of the considerations 

 that appear most important. 



BEHAVIOR OF GRAPES GRAFTED AND ON THEIR OWN ROOTS. 



In Table VII, column 1 gives (1) the variety name, and indented 

 under it (2) the name of the resistant stock on which it is grafted, or 

 if the variety is on its own roots the fact is so stated. Column 2 

 shows the experiment vineyard in which the growth was tested, use 

 being made of the following abbreviations: C for Chico, Cx for Col- 

 fax, F for Fresno, G for Geyserville, Gi for Guasti, L for Lodi, Li for 

 Livermore, M for Mountain View, O for Oakville, S for Sonoma, St 

 for Stockton. Column 3 shows the year in which the stock was 



