Micro- and Macro-Nutrients in Sieve-Tube Sap of Palms

The translocation and distribution of nutrients, taken in by the roots of plants will usually take place with the transpiration stream. For redistribution from the leaves to other parts of the plants—and this applies also to foliar application—nutrients have to travel with the stream of assimilates in the sieve tubes. The possibility for a nutrient to travel by means of the sieve tubes will determine whether a substance applied to the leaves will reach other parts of the plant or not. In the latter case the substance may be used up or held back in the leaves, or it may not be transferred at all. Mobility of a substance and transport through the sieve tubes is connected with its presence in the sieve-tube sap. Such sap can be obtained from the inflorescences of palm trees in rather large amounts (Tammes, 1933).