302 CITRUS FRUITS AND THEIR CULTURE. 



and the maturity of the fruit is somewhat hastened by 

 heavy applications of this material, unless offset by an 

 abundant supply of nitrogen. 



Potash. In the formation of starch, sugar, fruit and 

 woody parts of the tree, potash plays an active part. By 

 photosynthesis, starch is formed in the leaves, as a solid 

 substance. Before it can be transferred to the different 

 parts of the plant, it must be dissolved. Potash assists 

 in this process, thus enabling the starch to pass through 

 the cell walls of the plant. Sugar is probably formed 

 from starch and various other related compounds in the 

 plant which enter so largely into the composition of the 

 wood and fruit are probably derived from the same 

 source. The great importance of a goodly supply of pot- 

 ash can thus be easily understood. 



If large amounts of potash are taken up by the trees 

 it will be found that the rind of the fruit will be much 

 thinner than otherwise and the amount of rag will be 

 greatly lessened. A plentiful supply of potash in the 

 fruit has an excellent influence on its keeping quality. 

 If too little be present, the fruit will be soft and is likely 

 to break down shortly after removal from the trees. To 

 increase the keeping and carrying quality of citrus fruits 

 a large amount of potash with a small amount of nitro- 

 gen should be used. The influence of potash on the hard- 

 ening of the wood is worthy of note. Trees plentifully 

 supplied with potash are more likely to form firm, hard 

 wood, less liable to damage by cold and the attacks of 

 insects than if a preponderance of nitrogen be applied. 



Nitrogen. The effects of an abundant supply of ni- 

 trogen are much more apparent than the effects of an excess 

 of either potash or phosphoric acid. When the leaves have a 

 dark green, glossy color they are receiving plenty of nitro- 



