150 



FUNDAMENTALS OF FRUIT PRODUCTION 



In Various Tissues of Trees of Different Age. — Table 40 shows the variations 

 with age in the several parts of apple trees. It is noteworthy in connection 

 with what has been said of the relations of potash content to bearing that the 

 30-year old trees have the lowest percentage of potash in the leaves. These trees 

 were in full bearing as reference to the last column of the table shows. Further- 

 more, there is no reduction in the percentage of potash in the leaves of the 100- 

 year old tree which had ceased bearing. 



The leaves of a tree in full bearing contain much less potassium when they 

 fall than its fruit. This is true of potassium' even to a greater degree than of 

 phosphorus, as Table 41 shows. 



Table 41. — Pounds op Potash in Parts of a Full Grown Treei'" 



SULPHUR 



Data are not available to present a picture of what happens to sulphur 

 in the fruit tree as has been attempted with nitrogen, phosphorus and 

 potash. The inorganic sulphate taken from the soil is incorporated into 

 organic compounds as both sulphate and sulphide sulphur. As sulphate, 

 it occurs in some of the mustard oils, such as sinigrin; as sulphide, it 

 occurs in cystin, one of the amino-acids used in the construction of most 

 proteins. 



Because considerable amounts of sulphur are lost in ashing, deter- 

 minations of the sulphur content of ash are of little value. There are 

 indications that plants contain as much or more sulpKur than phosphorus, 

 but satisfactory analyses are yet to be made. 



The data in Table 42 are representative of a few reliable analyses of 

 sulphur in fruit plants. They show that fruit contains approximately as 

 much sulphur as phosphorus. 



Table 42. — Pounds op Sulphur in 1,000 Pounds of Fresh Fruits'"^ 



Apples 0.43 



Raspberries . 35 



Gooseberries 0.12 



Dewberries 0.37 



Cherries 1.08 



Red currants . 56 



Blackberries 0.40 



Grapefruit . 20 



Peach pulp 0.14 



Oranges . 26 



Lemons . 22 



Limes . 47 



Pineapple . 39 



Sulphur has been thought generally to be present in most soils in 

 amounts sufficient to meet the requirements of crop plants and recent 



