216 FUNDAMENTALS OF FRUIT PRODUCTION 



the indifferent ash, need not exceed 2.0 per cent, of nitrogen, 1.5 per cent, 

 of potassium oxid, and 0.5 per cent, of phosphoric oxid ... In compar- 

 ing excessive percentages with the foregoing amounts, it may be noticed 

 that in certain instances . . . the percentages have increased to the 

 following high magnitudes: Nitrogen, 3.96 and potassium oxide 5.56 in 

 1911 in rye; and phosphoric oxide 1.36 in 1916 in buckwheat. Of course, 

 these amounts are much in excess of what was necessary." The olive 

 has been said to have a higher oil content when grown on a limestone 

 soil.^^^ Presumably fertilizing the olive orchard heavily with lime would 

 have some influence in the same direction. Strawberries on nitrogen- 

 fertilized plants have been found to wilt more in times of severe drought 

 than those on unfertilized plants.-^ Wickson^''^ states: "Puffiness of 

 oranges is clearly due in some cases to excess of nitrogenous manures" 

 and "the effect of excessive use of stable manures, or of other manures 

 very rich in nitrogen, upon the products of the vine has been frequently 

 noted as destructive to bouquet and quality." 



There are a number of indirect ways in which fertilization, particu- 

 larly with nitrogenous fertilizers, influences composition. For example, 

 the use of nitrate of soda in the apple orchard has been shown frequently 

 to result in increased size of fruit; such differences in size are often 

 correlated with differences in texture, in juiciness and in what is generally 

 termed quality. These influences are not well enough understood, 

 however, to make possible definite recommendations for the developing 

 of certain quahties or substances, as sugar or acid or pectins, through the 

 use of fertilizers. Often resistance or susceptibility to certain diseases is 

 closely correlated with the chemical composition of the tissues subject to 

 invasion and even a slight change in composition that might be brought 

 about either directly or indirectly through the use of some fertilizer might 

 be of great use in reducing injury from the invading parasite or its toxin. 



The effect of nitrogenous fertilizers on season of maturity of the 

 wood has been mentioned. In the section on Temperature Relations 

 it is shown that the breaking of the winter rest period in certain fruits 

 is closely correlated with the time of maturing of the wood in the fall 

 and in turn susceptibility to low temperatures in late winter is associated 

 with the breaking of the rest period. Thus, indirectly, applications 

 of nitrogen may have an important influence on certain forms of winter 

 injury. Indeed the peach and some other fruits are probably grown 

 sometimes under conditions where fertilization with nitrogen-carrying 

 materials may be profitable for this reason if for no other. 



Application of nitrate of soda has delayed the ripening of peaches 

 in West Virginia from 1 week to 10 days, the delay being greater in 

 the later varieties.^ Observations elsewhere indicate that almost any 

 material carrying quickly available ' nitrogen has a similar influence 

 on many other fruits. 



