Mineral Nutrients 



141 



76. Translocation of mineral substances. It is well 

 known that as a plant begins to develop fruit or seed there 

 is generally a movement of certain elements or substances 

 to these parts. They may become the storage organs of 

 carbohydrates, proteins-, and other organic compounds, 

 but there is also a selective absorption of mineral constit- 

 uents. Throughout the period of fruit formation phos- 

 phoric acid migrates toward the fruiting organs from leaves 

 and stems ; and magnesium is invariably translocated, espe- 

 cially from the lower leaves and stem to the younger organs 

 of the upper portion, or to the fruit. Potassium frequently 

 reaches a maximum in the fruiting organs at the time of 

 blossoming, and subsequently may be slightly replaced by 



PHOSPHORIC ACID CONTENT AT VARIOUS STAGES OF GROWTH 



PART OF PLANT 



PERIODS OF GROWTH 



